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Health Desk articles

How can we tell if an increase in cases is the result of an increase in testing or something else?

A lot can be learned and based off of the percent-positive rate (e.g. how many tests result positive out of all the tests taken) and the number of cases in total. We cannot assume that an increase in cases or a growing percent-positive rate is purely a result of an increase in testing instead of a growing outbreak. Instead, we need to look at all of them together. A rise in the number of reported cases of COVID-19 could be related to an expansion of testing if the percentage of positive tests decreases or stays the same at the same time that the number of cases increases. Should percentage of positive tests increase while case counts also go up, this indicates that we cannot entirely blame the increase on expanded testing. The biggest indicator of a growing outbreak is if the percentage of positive tests increases along with the number of cases despite testing data staying the same or decreasing. When testing is not always widely available and reserved just for symptomatic people, the percent positivity will increase as with the number of cases. If testing is expanded and made more available, we will gain a better understanding of the true number of cases and percent-positive rate. If this percent positivity continues to grow along with the number of cases, this would be an indicator that the outbreak is worsening.

What do we know about the Pfizer vaccine so far?

The Pfizer vaccine is being developed and produced by Pfizer, Inc. and the biotech company BioNTech SE. It is a genetic mRNA vaccine (mRNA-1273) currently in Phase 3 clinical trials across the globe. Here is a breakdown of everything you need to know so far about this vaccine’s development. \*\*Collaborators: \*\*Biopharmaceutical company Pfizer Inc, based in New York City, and BioNTech, biotechnology company based in Mainz, Germany, are collaborating on vaccine development and testing for the mRNA-based vaccine candidate BNT162b2. \*\*Latest information on how well the vaccine works:\*\* On November 30, 2020 with primary efficacy analysis data from its Phase 3 trial, Pfizer announced its experimental COVID-19 vaccine to be 95% effective 28 days after the first of two doses.  Out of approximately 44,000 total study participants, 170 contracted COVID-19. 162 who got infected were from the placebo group—meaning they didn’t receive the vaccine—and only 8 who got infected were in the group that was vaccinated with the Pfizer vaccine.  Ten of the COVID-19 cases were severe. Nine of those people were from the placebo group. One severe case was in the vaccinated group. This suggests the vaccine has high protection for severe COVID-19 cases, at 95% efficacy, meaning that if 100 study participants were the vaccine doses, 95 patients would not contract the disease and 5 would.  There have been no reported COVID-19-related deaths in the study. These new results of 95% efficacy are higher than the vaccine’s first interim analysis conducted during the study (announced on November 9th, 2020), which reported 90% efficacy based on an analysis of 94 COVID-19 cases among trial participants. Based on a study published in February 2021 in the New England Journal of Medicine, the Pfizer-BioNTech vaccine was found to appear to be highly effective against the more transmissible variant of the virus first detected in the U.K. (B.1.1.7) (virtually no drop from 95% efficacy). However, the vaccine showed a decreased ability to neutralize the strain first detected in South Africa (B.1.351). Specifically, they found that there was about a two-thirds drop in neutralization power (antibody power) against this variant compared to other forms of the SARS-CoV-2 coronavirus. It’s important to note that the vaccine was still able to neutralize the virus, and likely still may protect individuals from getting severe forms of the virus. In addition, these are initial lab experiments that are difficult to extrapolate results from. Pfizer has said that evidence is needed to understand how the vaccine works against the variant in real life. The company stated, "Nevertheless, Pfizer and BioNTech are taking the necessary steps, making the right investments, and engaging in the appropriate conversations with regulators to be in a position to develop and seek authorization for an updated mRNA vaccine or booster once a strain that significantly reduces the protection from the vaccine is identified.” \*\*Approvals:\*\* As of December 2, 2020, the U.K. authorized the distribution of Pfizer and BioNTech’s COVID-19 mRNA vaccine BNT162b2 for emergency supply, making the vaccine the first in the world to achieve authorization for COVID-19. Two days following the U.K.’s authorization, Bahrain approved the emergency use of the Pfizer and BioNTech vaccine, making it the second country in the world to do so. Five days following on December 9, Canada’s regulatory agency Health Canada approved the vaccine. On Friday, December 11, 2020, the U.S. Food and Drug Administration (FDA) authorized the Pfizer and BioNTech vaccine. Soon after, Pfizer and BioNTech bega rolling review processes with other global regulatory bodies, including in the U.S., Europe, Australia and Japan, and has been submitting applications to other regulatory agencies around the world, primarily in the Global North, with a range of approvals. \*\*Distribution timeline:\*\* Following the U.K.’s emergency approval on December 2, 2020, the companies began delivering the first doses to the U.K. nearly immediately, starting on December 8, 2020. Canada is set to receive 249,000 doses before the end of December to distribute across 14 different vaccination sites throughout Canadian cities. Following the U.S. approval of the vaccine on December 11, 2020, the U.S. will initially distribute approximately 2.9 million doses to all 50 states.  The distribution timeline for other countries undergoing the approval process will depend on the distribution decisions made by regulators there. Some countries are already coordinating pre-approval distribution and in many of these regions and countries, logistics surrounding the supply chain of the vaccine are being decided upon and run through so that when there is an approval, distribution can begin immediately. \*\*Distribution plan:\*\* In projections, Pfizer hopes to produce and supply up to 25 million vaccine doses in 2020 and 100 million doses before the start of March, with an estimated total distribution of up to 1.3 billion doses in 2021. Four of Pfizer’s facilities are part of the manufacturing and supply chain; St. Louis, MO; Andover, MA; and Kalamazoo, MI in the U.S.; and Puurs in Belgium. BioNTech’s German sites will also be leveraged for global supply. Each of these sites are important links in a global supply chain being assembled to tackle the massive logistical challenge of distributing COVID-19 vaccines around the world.  Jurisdictions primarily have the responsibility of determining who receives the vaccine in what order. For instance, within the U.S. each state will receive a certain number of doses of the vaccine based on residential populations. States have been asked to create their own plans for who will get the first doses.  In the U.K., British front-line health-care workers, as well as care-home staff and residents, are receiving the first doses. Bahrain has said that they plan to inoculate everyone 18 years and older at 27 different medical facilities, hoping to be able to vaccinate 10,000 people a day; so far, they have the second-highest vaccination rate in the world behind Israel. In general, the most likely distribution plan is for the vaccine to first go to emergency department clinicians, outpatient clinicians, testers at symptomatic sites, other high-risk health care workers, immunocompromised individuals, EMTs, and potentially essential federal employees, followed by the rest of the general population.  Vaccination distribution in some countries is moving more slowly than anticipated. In the U.S, for example, just 2.6 million individuals were vaccinated by December 31, 2020 compared to the 20 million goal by the end of 2020. In response, scientists and public health practitioners are considering vaccination tactics that differ from those that the FDA and other country’s health regulatory bodies approved. The tactics being considered are primarily halving doses of vaccines and delaying second doses to get first doses to more individuals, but also include reducing the number of doses and mixing and matching doses.  Health officials in the UK have already decided to delay second doses of two vaccines, one made by AstraZeneca and one made by Pfizer and BioNTech, and to mix and match the two vaccines for the two doses under limited circumstances. This decision has received mixed responses from scientists and public health practitioners, many of whom are concerned about the lack of data, particularly with regards to a mix-and-match approach.  The U.S. FDA critiqued the idea of halving the doses of the Moderna vaccine, saying that the idea was “premature and not rooted solidly in the available science.” Studies are underway to determine whether doses of the Moderna COVID-19 vaccine can be halved to 50 micrograms in order to double the supply of the vaccination doses in the U.S., according to the National Institutes of Health and Moderna.  \*\*Vaccine storage conditions:\*\* Storage requirements are important to consider for new vaccines. In order for vaccines to be safe and effective, they must be held at the correct temperature during distribution and storage in health centers, pharmacies, and clinics. Maintaining the correct storage temperature can be difficult, especially if the vaccine’s temperature requirement is very cold.  The Pfizer and BioNTech vaccine can be stored for five days at refrigerated 2-8°C (36-46°F) conditions (refrigerators that are commonly available at hospitals); up to 15 days in Pfizer thermal shippers in which doses will arrive that can be used as temporary storage units by refilling with dry ice; and up to 6 months in ultra-low-temperature freezers, which are commercially available and can extend the vaccine’s shelf life.  With regards to transit, Pfizer is using dry ice to maintain the recommended temperature conditions of -70°C±10°C (-94°F) for up to 10 days while in transit. However, Pfizer and BioNTech have determined that the vaccine can be moved only four times. \*\*Type of vaccine:\*\* The mRNA-1273 vaccine is what scientists are calling a genetic mRNA vaccine. This type of vaccine works by using genetic information from the coronavirus, which is injected into the body. The genetic information enters into human cells, instructs the body to make special spike proteins like the coronavirus, and causes the immune system to respond. \*\*Dosage:\*\* In the current Phase 3 clinical trial, participants receive two injections of 30 micrograms each into their upper arm muscle. The injections are given 21 days apart. Once an individual gets the first dose, they must get the second dose three weeks later in order to complete the vaccination. If approved, researchers expect that the same dosage and schedule will be prescribed to the public. A recent Israeli study that released results in February 2021 by the Lancet found that a single dose of the Pfizer vaccine was 85% effective against COVID-19 infection between two and four weeks after the first dose, and that the overall reduction in infections was 75%, including asymptomatic cases. Public health practitioners are enthusiastic about this finding of high efficacy after just one dose; However, the authors cautioned that the low numbers of COVID-19 cases in the study, and the fact that the study was conducted at one hospital, make it difficult to reach exact estimates and that these findings should be interpreted with caution. The study also does not determine the length of protection. Pfizer did not comment on the data, stating that “the vaccine’s real-world effectiveness in several locations worldwide, including Israel.”   Studies out of the U.K., which has been the quickest to inoculate its population, have also found that a single dose of the Pfizer vaccine could avert most COVID-19-related hospitalizations, though investigators stated it was too early to give precise estimates of the effect. \*\*How the vaccine is being studied:\*\* Vaccines are tested and studied in multiple phases (phased testing) to determine if they are safe and work to prevent illness. Before a vaccine is tested on humans, which is known as the preclinical phase, it is tested on laboratory cells or animals. Once it is approved for human research, there are three phases that take place before the vaccine can be considered for approval for public use. During the first stage (Phase I), the new vaccine is provided to small groups of people—the first time the vaccine is tested in humans to test safety (primarily) and efficacy of the vaccine.  The second stage (Phase II) involves testing the vaccine on people who have similar characteristics (such as age and physical health) to the target population, or the group for which the vaccine is intended. The goal of this stage is to identify the most effective doses and schedule for Phase III trials. The final stage (Phase III) provides the vaccine to thousands of people from the target population to see how safe and effective it is.  Once the vaccine has undergone Phase 3 testing, the manufacturer can apply for a license from regulatory authorities (like the FDA in the US) to make the vaccine available for public use. Once approved, the drugmaker will work with national governments and international health organizations to monitor vaccine recipients for potential side effects from the vaccine that were not seen in clinical trials (this is called surveillance). This phase also helps researchers understand how well a vaccine works over a longer time frame and how safe it is for the population. \*\*How Pfizer looked for COVID-19 cases in their trials:\*\* Researchers have standard definitions for routinely detecting COVID-19 cases for both symptomatic and asymptomatic individuals. For symptomatic individuals, there are three definitions considered for defining a COVID-19 case for the study. The first two are for regular cases, and the third is for severe cases.  The first definition is the presence of at least one COVID-19 symptom and a positive COVID-19 test (such as a PCR test) during, or within 4 days before or after, the symptomatic period, either at the central laboratory or at a local testing facility. The second definition is the same, but expands the definition to include four additional COVID-19 symptoms defined by the CDC (fatigue; headache, nasal congestion or runny nose, nausea). The third definition, which defines severe COVID-19 cases for the study, is a confirmed COVID-19 test per the above guidelines in addition to one of the following symptoms: clinical signs at rest indicative of severe systemic illness, respiratory failure, evidence of shock, significant acute renal, hepatic, or neurologic dysfunction, admission to an ICU, or death. The Pfizer research protocol states that for individuals who do not clinically present COVID-19 (that is, asymptomatic individuals), a serological test is used for defining a case, which measures the amount of antibodies or proteins present in the individual’s blood, and a positive case is defined as the presence of antibodies in an individual who had a prior negative test. By using these four definitions, researchers are able to detect COVID-19 cases in both symptomatic and asymptomatic individuals. However, the pharmaceutical company has stated that there are more data on the vaccine’s safety and efficacy for symptomatic cases, and that more data is needed to better understand the vaccine’s safety and efficacy for asymptomatic cases. \*\*Preclinical testing:\*\* Before testing could begin on humans, the trial vaccine was tested on primates at both 30 micrograms and 100 micrograms. On September 9, 2020, results were published demonstrating that the Pfizer vaccine had strong antiviral protection against the virus SARS-CoV-2. As a result, the Pfizer and BioNTech were permitted to advance the vaccine into human clinical trials by the FDA in the form of through the Investigational New Drug application (IND). \*\*Phase 1 trial:\*\* 45 healthy adults 18–55 and 65–85 years old were randomly assigned to either the placebo group or the vaccine group to receive 2 doses at 21-day intervals of placebo or either of 2 mRNA-based vaccines (BNT162b2 or BNT162b1, which was one of several RNA-based SARS-CoV-2 vaccines studied in parallel for selection to advance to a next trial). Participants received either 10, 20, or 30 microgram dose levels of BNT162b1, or BNT162b2 on a 2-dose schedule, 21 days apart. Both participants and observers working on the study were “blinded,” or not aware of which participants were receiving the active vaccines (and which ones) versus the treatment, in order to help prevent bias.  Both with 10 micrograms and 30 micrograms of vaccine BNT162b1, and t 7 days after a second dose of 30 micrograms of the BNT162b2 vaccine, “SARS-CoV-2–neutralizing antibodies” were elicited—special proteins that disable viruses in the body—in younger adults (18-55 years of age) and older adults (65-85 years of age). Younger participants had 3.8 times more antibodies than people who had recovered from the virus. In older adults (65-85 years of age) the vaccine candidate triggered antibodies at 1.6 times the volume of those who had recovered from the virus in the same age group. Vaccine BNT162b2, now known as the “Pfizer vaccine,” was associated with fewer reactions (such as fever and chills), and was therefore selected for Phase 2/3 trials.  In terms of safety and tolerability of vaccine BNT162b2, reactions were still reported. Study participants reported pain at the injection site, headache, fatigue, muscle pain, chills, joint pain, and fever. Most of these reactions and symptoms peaked by the day after vaccination and resolved by day 7.  \*\*Phase 2/3 trial: \*\*In an effort to speed up the trial, Phases 2 and 2 of the Pfizer vaccine were combined. This phase continued off of Phase 1 and also contained a placebo group as a control with patients randomly assigned into either the placebo group or vaccine group for vaccine BNT162b2. As with Phase 1, the observers and participants were also “blinded.” The first 360 participants enrolled made up the “Phase 2” portion, with 180 randomly assigned to receive the active vaccine and 180 to receive the placebo, stratified equally between 18 to 55 years and >55 to 85 years. Phase 3 enrolled 43,538 trial participants overall, half of whom were randomly assigned to receive the vaccine and half of whom were randomly assigned to receive the placebo. Out of 170 cases of COVID-19 among the study participants,162 cases of COVID-19 were observed in the placebo group versus 8 cases in the vaccine group, indicating 95% efficacy of the vaccine. No serious safety concerns were observed. Data collection is ongoing. \*\*Reported side effects and safety concerns:\*\* The study’s Data Monitoring Committee did not report any serious safety concerns related to the vaccine based on the trial data. Adverse events at or greater than 2% in frequency that were reported were fatigue at 3.8% and headache at 2.0%. Potential allergic reactions occurred in 0.63% of those who received the vaccine, compared with 0.51% of those who received the placebo.  On December 9, one day after the Pfizer and BioNTech vaccine began being distributed to individuals outside of the clinical trial in the UK, UK regulators advised that individuals with a history of anaphylaxis to a vaccine, medication, or food should not receive the vaccine. This warning was issued in response to two reports of anaphylaxis (severe allergic reaction) -- both among individuals with histories of severe allergies -- and one report of a possible allergic reaction since distribution in the UK began. Pfizer and BioNTech have stated that they are working with investigators to better understand the cases and causes of the reactions.  Within the clinical trial, individuals with a history of severe allergic reactions were excluded from the trials, and doctors were asked to look for such reactions in trial participants who weren’t previously known to have severe allergies. UK regulators also required health care workers to report any negative reactions to help regulators collect more information about safety and effectiveness.  In addition, four people who received the vaccine during trials later developed Bell’s palsy at 3, 9, 37, and 48 days after vaccination, respectively. Because these trials were so large, however, this is not more than we would expect to develop Bell’s palsy in a group of this size by chance. Bell’s palsy is a weakness or paralysis of one side of the face which is usually temporary. Any cases of Bell’s palsy and any other potential side effects or adverse reactions will continue to be monitored and evaluated for as the vaccine continues to be rolled out to the public. \*\*Impact on different populations:\*\* Pfizer and BioNTech both say they aimed to make their trials as diverse as possible to understand the vaccine’s effect on different populations. The trial participants are approximately 30% U.S. participants and 42% non-U.S. participants from across 150 trial sites globally. The participants are reported to have racially and ethnically diverse backgrounds. In the trials, 41% of global and 45% of U.S. participants are 56-85 years of age. Efficacy was reported to be consistent across age, gender, race and ethnicity demographics.  Notably, the observed efficacy in individuals over 65 years of age was observed to be greater than 94%. In September 2020, Pfizer and BioNTech expanded Phase 3 enrollment to approximately 44,000 participants. This expansion allowed for the enrollment of new, more diverse, populations, including adolescents as young as 16 years of age, and individuals with chronic, stable human immunodeficiency viruses (HIV), Hepatitis C, or Hepatitis B infection. In October 2020, Pfizer and BioNTech received permission from the FDA to enroll adolescents as young as 12. Their explanation for these expansions is to enable better understanding of the potential safety and efficacy of the vaccine in individuals from more ages and backgrounds.

What does colder weather mean for the spread of COVID-19?

We do not know how the COVID-19 virus will impact people during colder winter months, but many experts predict higher rates of transmission and mortality than during the warmer, summer months. This is likely due to the impact cold weather has on human behavior such as forcing people inside where higher temperatures are preferred and ventilation is not sufficient to combat the spread of the virus. With groups of people congregating in confined spaces with limited airflow, the virus is able to circulate easily through aerosolized particles and respiratory droplets. Additionally, since a large percentage of COVID-19 have asymptomatic infections but they are still able to transmit the virus, many infected people are likely not restricting their movements to one quarantined room or area or taking necessary distancing or masking protocols. Traditionally, viruses like influenza and the common cold tend to increase amounts of infections in the winter and decrease in the summer. As with these other respiratory viruses, COVID-19 transmission will be impacted dramatically by control and prevention measures like social distancing, masking, and vaccination. The more people who engage in these activities, the more likely infections can be prevented. Though some viruses do not like humid, hot conditions, COVID-19 has been shown to spread rapidly in some regions during warm spring and summer months in both hemispheres. A study from October 13, 2020, before widespread prevention measures were undertaken showed that infections increased more quickly in places with less UV light and suggested that without any interventions, case rates may be highest in the winter and lower in the summer. However, weather itself does not appear to have an impact on the ability of the virus to spread though colder weather may make it more difficult for the body to fight respiratory infections. At this point, it is unknown whether or not COVID-19 will become a seasonal virus like influenza but we should expect any event that brings together people in closed environment can lead to an increased spread of the virus.

Does wearing a face mask put you at higher risk of cancer?

Wearing a face mask does not put you at a higher risk of cancer. There is no current evidence linking the use of face masks to cancer, and science shows that any risks associated with wearing masks are low overall, while the benefits are high.  Because of how tiny oxygen and carbon dioxide molecules are, face masks neither decrease the amount of oxygen that enters a mask nor increase the amount of carbon dioxide that stays in a mask. As a result, face masks do not disrupt the body’s pH levels, affect the bloodstream, or alter one’s body in any way that would put someone at higher risk of cancer. The claim that wearing face masks causes cancer has been circulating on Facebook and other social media platforms, citing a January 2021 study that did not study face masks or mask wearing in general. An article from Blacklisted News falsely suggested that mask wearing can lead to reproduction of bacteria, which then leads to cancer. The articled stated that harmful microbes can grow in a moist environment, like the ones created around the mouth and face because of constant mask wearing. The article suggests that microbes can grow and replicate before traveling through the trachea into blood vessels in the lungs. From there, they allege the the microbes cause an inflammatory response. It's true that oral bacteria can contribute to oral infections, dental plaque, and cancer. However, bacteria is also a normal part of our skin and other organs. It can contribute to health in positive and negative ways. The study that linked mask wearing to the development of advanced lung cancer did not involve long-term mask wearing as part of the study. The article that wrote about it falsely assumed that masks could be the cause of this bacteria, rather than its normal presence in the human body and microbiome. There is no evidence that mask wearing can pose a danger to health, including altered carbon dioxide and oxygen levels. Bacteria can build up over time in a mask, so they should be cleaned and dried properly. This build up does not cause cancer.  The American Lung Association verified that masks cannot cause lung cancer and the United States Centers for Disease Control and Prevention noted that any carbon dioxide build up in masks should not impact people who wear face masks in order to prevent COVID-19 infections and transmission.

Is indoor dining safe now, especially in covered tents?

Indoor dining is still high risk when it comes to dining during the COVID-19 pandemic, even if the dining takes place in covered tents. The SARS-CoV-2 virus that causes COVID-19 mostly spreads from person to person. The virus is transmitted from infected people when they cough, sneeze, talk, or sing, which can be transmitted through droplets in the air: droplets that fall and then are transmitted through surfaces, or through airborne transmission, which is when droplets are very light and remain suspended. An individual who might be in close proximity to an infected person can then inhale the virus and get infected themselves, or touching their nose, mouth, or eyes after touching the virus. The virus can even spread through people who do not show any symptoms but are infected with COVID-19. When dining indoors with individuals outside of your household, the risk for transmission of COVID-19, particularly through airborne transmission, is increased substantially compared to outdoor dining and dining at home. Covered tents that hold multiple tables at once have the possibility of being slightly safer than a fully insulated, indoor restaurant, but it depends on the design of the tent, and is still a risk given that multiple people from different households are sharing space without being in fully open outdoor air.  Single-table tents are still a risk if they are not aired out for at least three hours before seating a new table, as COVID-19 that is aerosolized can remain in the air for up to three hours. If the three-hour time span is allotted for airing out single-table tents, the method is only effective if they’re used by individuals of the same household, and even then there’s a non-zero chance that COVID-19 could still be in the air if someone from a previous sitting was infected.  The U.S. CDC ranks on-site dining with indoor seating capacity reduced to allow tables to be spaced at least 6 feet apart, and/or on-site dining with outdoor seating, but tables not spaced at least six feet apart as high risk, and ranks on-site dining with indoor seating or with seating capacity not reduced and tables not spaced at least 6 feet apart as highest risk. Design concerns to consider with regards to COVID-19 safety include airflow, which is extremely important for ventilating a space and decreasing risk (eg. three walls of tent seating as opposed to a fully enclosed four makes a significant difference); the number of people allowed in the space (the fewer people, the better); the distance between tables (at least 6 feet and the further the better); humidity levels, if relevant (the more humid, the better); and if the restaurant has explicit rules around mask use and safety.

What do we know about mouth and nose rinses, washes, sprays, or creams to prevent COVID-19?

There is no scientific evidence to support using home or traditional therapies to prevent COVID-19 at this time. The World Health Organization (WHO) and other international health leaders say that caution is needed when considering “traditional remedies” as preventative measures or treatments for COVID-19, because they have not been widely studied and may cause harm in some cases. There are many traditional remedies and home remedies that have been promoted to prevent COVID-19 infection. People have suggested using mouth or nasal washes, sprays, and creams (or fats) could prevent the virus from entering the body or kill the virus in the nasal cavity (nose) and throat before it has a chance to spread. **Nasal (nose) washes:** There is no scientific evidence that suggests rinsing the inside of your nose will prevent COVID-19 infection. Additionally, for patients with COVID-19, researchers have raised a concern about using contaminated nasal rinse bottles (as well as surfaces and rinse fluids), suggesting they could be a source of exposure. **Nasal (nose) sprays:** Ongoing studies seek to learn more about how saline, iodine, special soaps, and other ingredients used as nasal washes and sprays may help improve virus symptoms and decrease the spread of COVID-19.  One Israeli study published in November 2020, and recently re-released with updates as a pre-print in January 2021, shows promising results for a nasal spray known as Taffix. Taffix is a nasal inhaler approved for sale and used for the prevention of respiratory viral infections in Israel and some other countries. The 2020/2021 study analyzed 243 members of a Jewish ultra-orthodox synagogue community during a high holiday, in which individuals were gathered and praying throughout the day. At the two-week follow-up mark of the event, the study investigators found that the individuals who used Taffix had a reduction in odds of COVID-19 infection by 78%, compared to those who did not use Taffix. Eighteen members out of the total 243 were infected with COVID-19, 16 in the no-Taffix group and 2 in the Taffix group, both of whom did not adhere to the recommended use. Studies are ongoing to test over the counter and other types of nasal sprays for protection against COVID-19, with some showing early promise in lab and animal studies. **Mouthwash, rinses, and gargle solutions:** Like nasal washes and sprays, there is no scientific evidence that suggests using mouthwashes, rinses, and gargles will prevent COVID-19 infection. Ongoing studies seek to learn about how special antiseptic mouthwashes may help prevent COVID-19 (see the Experimental Therapies section below). So far, many studies have explored these treatments in laboratory cells, and data on humans is limited. **Alcohol, chlorine, or disinfectant spray:** Alcohol, chlorine (e.g. bleach solutions), or disinfectant sprays should never be sprayed or applied to your nose, mouth, or eyes, and doing so may cause serious harm. Drinking alcohol will not prevent or treat COVID-19. **Fats or oils:** This includes coconut oil, ghee, sesame oil, shea butter, petroleum jelly, and others. There is no scientific evidence that nasal treatments or mouth rinses with different fats will prevent, treat, or cure COVID-19. While many types of fats or oils (like coconut oil, sesame oil, and others) have been shown to kill or stop bad bacteria in cell-based laboratory studies, most of these studies have focused on how these ingredients may be used to prevent bacterial growth on food to improve food safety. Studies have not looked at the effect of fats on prevention of viral or bacterial infections in humans when applied in the nose or used as a mouth rinse. There is no scientific evidence that supports the theory that using these oils would improve health or prevent illness. In addition, though rare, it is possible that inhaling fats from the inside of the nose can cause lung problems. **Steam inhalation:** Though inhaling steam may help to thin mucous or relieve congestion (stuffy nose), there is no scientific evidence to suggest that inhaling steam will prevent or treat COVID-19. Contact with steaming hot water can cause burns, and inhaling steam can burn the inside of your nose. **Experimental therapies:** There are ongoing studies using nasal sprays (and rinses) and special mouthwashes to prevent COVID-19, such as the Taffix study discussed above. Much of the current scientific evidence is based on animal or laboratory cell studies. For humans, efficacy and safety studies are ongoing, and most treatments are not recommended for the public at this time. Currently, studies seek to understand if nasal rinses (using saltwater, special soaps, and other ingredients) may help to improve symptoms and decrease the viral load in patients with COVID-19 (with the thought that decreasing the viral load could decrease how much an infected person may spread the virus). Researchers are also studying whether gargling or rinsing with special solutions (e.g. povidone-iodine) may help prevent healthcare workers from contracting COVID-19. A pre-print study or a nasal spray medication (INNA-051) has shown good results in preventing COVID-19 in ferrets, but human studies have not yet begun. Human study results for Taffix nasal spray and its pre-existing approval for prevention of respiratory viral infections makes it feasible for human use in protection against COVID-19; however, it is not a replacement for mask use and physical distancing. To prevent COVID-19 infection, health authorities continue to recommend avoiding crowds, practicing social distancing measures (at least 6 feet/2 meters apart), frequent and careful handwashing, wearing face masks (wearing a cloth mask over a surgical mask is recommended by the U.S. Centers for Disease Control and Prevention), staying home when possible (especially if you are sick), clean high-touch surfaces often, and avoid touching your nose, eyes, and mouth.

What do we know about the Regeneron cocktail for COVID-19?

Regeneron Pharmaceuticals, Inc., an American biotechnology company, recently received Emergency Use Authorization (EUA) for its COVID-19 antibody cocktail treatment of casirivimab and imdevimab by the United States. The treatment formerly known as REGN-COV2 is the first combination therapy to receive an EUA and can be used to treat mild to moderate cases of COVID-19 in recently diagnosed patients at high risk for severe cases of the virus and/or hospitalization. The treatment can also be used in pediatric patients at least 12 years of age and weighing at least 88.2 pounds or 40kg. It is an experimental drug that is designed to help the body prevent and fight off the virus. The drug is called a 'cocktail' because it mixes a combination of drugs so that it can be more effective and in this case, prevent the virus from becoming resistant to the treatment. This particular drug from Regeneron uses a combination of two "monoclonal antibodies," casirivimab and imdevimab. Antibodies are part of the immune system, and they help fight off infections and foreign invaders like COVID-19 by finding the virus, neutralizing it, and telling the rest of the immune system to begin launching its response. Monoclonal antibodies (which means 'one type of antibody') are antibodies created in a lab that can act as a replacement for the antibodies the body normally creates. These lab-made antibodies are different than the ones that the immune system creates naturally because they're uniquely designed to target and launch an attack against the specific the virus that causes COVID-19. Regeneron believes that individual antibody therapies are likely not strong enough to fight the virus that causes COVID-19, so they have combined two separate antibody treatments into one as a weapon to fight against the virus and prevent any drug resistance that might occur if they virus mutates and escapes the effects of the antibodies (called "viral escape"). Casirivimab and imdevimab are the two monoclonal antibodies in this cocktail which aims to help patients who were recently diagnosed with COVID-19 but have not yet launched their full immune system response, or who have a lot of the virus circulating in their blood. Additionally, this treatment is not authorized for use in people who are hospitalized or who need oxygen; just those with mild to moderate cases who recently tested positive for COVID-19. Regeneron also recently announced that people who received its antibody treatment had a lower number of medical visits for COVID-19 related causes in comparison to those who did not receive the treatment. Patients who received the antibody treatment made roughly 57% fewer visits to seek medical care than patients who received a placebo. In patients at high risk for serious complications from the virus (like those over 50 and people with cardiovascular or lung conditions), the reduction in visits was 72% lower than the group who did not receive the drug. Patients who were given the treatment also demonstrated lower levels of the virus in their blood and less severe symptoms than patients who did not receive the treatment. Though Regeneron's monoclonal antibody treatment has received an EUA, that authorization is only temporary so the cocktail therapy will continue to be evaluated in phase 2 and 3 clinical trials, according to the company. As of November 24, 2020, more than 7,000 people have participated in Regeneron's casirivimab and imdevimab clinical trials. The United States' government began distributing the treatment on November 24, 2020 starting with 30,000 treatment courses and expects to produce enough of the therapy to reach 80,000 patients by the end of November 2020. Regeneron's antibody cocktail is part of the United States' Operation Warp Speed and has received more than $500 million from the government to develop these treatments. This public–private partnership's goal is to create and distribution vaccines, therapies, and diagnostics for COVID-19 rapidly and safely and involves various government agencies and companies.

Why would it have been hard for AstraZeneca to discover blood clots in clinical trials?

The AstraZeneca vaccine went through rigorous Phase 3 testing and regulatory approval processes before being administered in the general public where it has been approved. In the reported Phase 3 trial data of more than 23,000 people, a total of 175 severe adverse events were reported (84 in the study group, 91 in the control group). Three events were considered possibly related to either the control or experimental vaccine. These events included one case of hemolytic anemia (in the phase 1/2 study control group), one case of transverse myelitis (in the study group 14 days after the second vaccine dose), and a case of high fever without another diagnosis (the patient information remains masked as part of the trial). Blood clots were not mentioned in the study published online on December 8, 2020. In clinical trials, it can be very difficult to identify uncommon side effects or serious adverse events (or reactions). When an event is uncommon, it can take a very large study group for it to be observed in research even once. Vaccine studies are designed to evaluate if the vaccine works, and if it is safe. COVID-19 vaccines were studied in clinical trials with thousands of participants before emergency use approval. Even with diverse and large study groups, it is possible that some side effects, reactions, or serious adverse events may not have been seen in the study population. Events that only occur in a few people out of a million or more can be very difficult to detect. In statistics there is a formula that is sometimes used to estimate how many people would need to be studied to detect a serious adverse reaction (SAR). The formula is called the rule of three. For example, if a medication were to cause a SAR in 1 person in every 1,000, then a company would need to study 3,000 people (the rule of 3) in order to have a 95% chance of observing or detecting even one case. For even more rare events that may occur in 1 person in every 10,000, a company would need to study 30,000 people to have a 95% chance of observing or detecting one case. For comparison, the type of rare blood clotting that was observed is estimated to occur in only a few people out of every million.  To help understand more rare adverse effects, drugs and vaccines are studied even after they are approved for the public. Data collection continues for years. This Phase 4 study (or observation) continues as the sample size of the study population is much larger, currently in the many millions for the COVID-19 vaccines. Researchers are continuing to gather data and information about events that occur in people who have received the vaccine. In Epidemiology: An Introduction, a text by Kenneth Rothman, the author notes that a lot of the data around drug safety “comes from studies that are conducted after a drug is marketed.” For the COVID-19 vaccines, government agencies (like the U.S. Food and Drug Administration and others) are collecting data about possible adverse events. Suspected adverse events are reported to the agency, and the agency investigates further. A reported or possible association does not mean that a vaccine caused an event to happen.  Trained researchers monitor and analyze data from these reports. They try to evaluate whether it is likely that the reaction was caused by the vaccine. To do so, they study the possible pathways that could cause the reaction to occur. They also compare the probability of the reaction in those who have been vaccinated to the probability of the reaction in those who have not. Now that many millions of people are being vaccinated with the new COVID-19 vaccines, it is not surprising that some rare events, like allergic reactions and blood clots, are being reported. Researchers now need to work to determine if the events are related to the vaccines and why. Many thousands of blood clots are diagnosed every year. Immobility, surgery, obesity, and smoking are some of the many risk factors. According to the European Medicines Agency, it is possible that blood clots could also be related to receiving the AstraZeneca COVID-19 vaccine. There has not been evidence of issues related to specific batches or a particular manufacturing site for the AstraZeneca vaccine. As of April 4, 2021, a total of 222 cases of thrombosis (169 cases of cerebral venous sinus thrombosis and 53 cases of splanchnic vein thrombosis have been reported) have been reported to EudraVigilance - the European system for managing information about serious adverse reactions to medicines. About 34 million people had been vaccinated in the European Economic Area and United Kingdom by this date.  On April 7, 2021, the European Medicines Agency safety committee concluded “that unusual blood clots with low blood platelets should be listed as very rare side effects of Vaxzevria (formerly COVID-19 Vaccine AstraZeneca).” The U.K. regulatory agency recommended alternatives to the AstraZeneca vaccine to be given to people under 30 years of age, following 79 reported cases of blood clotting and 19 deaths. As of April 16, 2021, the Australian regulatory agency is also conducting a review of the AstraZeneca vaccine following three reported instances of rare clotting, including one fatal case. AstraZeneca has not applied for regulatory approval in the United States, but another viral vector vaccine for COVID-19 made by Johnson & Johnson is also under review for rare blood clotting as of April 13, 2021. Regulatory agencies take vaccine safety seriously and often exercise an abundance of caution. COVID-19 vaccines have been credited with saving lives and reducing hospitalizations on a large scale. 

What do we know about the risks of combining more than one of the approved vaccines?

For COVID-19 vaccines that require more than one dose, such as the Pfizer-BioNTech and Moderna vaccines, researchers are still learning about the outcomes of mixing a first dose of one vaccine with a second dose of another. In the clinical trials that have led to emergency authorization of COVID-19 vaccines, combining doses from different vaccines has not yet been tested. This means that scientists do not yet know if combining doses from different COVID-19 vaccine candidates will be as effective or safe. To help provide more data, a clinical trial was announced on February 8, 2021 to begin testing the combination of one dose from the AstraZeneca vaccine candidate with one dose from the Pfizer-BioNTech vaccine candidate. This clinical trial, dubbed Com-Cov, is being led by the University of Oxford and is considered the first in the world to test the combination of different COVID-19 vaccine candidates. Enrollment of 820 participants over 50 years of age is starting, and scientists hope this clinical trial can provide more data and insights by the summer of 2021. It is important to remember that outcomes can potentially vary depending on which COVID-19 vaccines are mixed. For this reason, the first clinical trial testing a combination of the AstraZeneca and Pfizer-BioNTech vaccine candidates may eventually add additional vaccine candidates. As more COVID-19 vaccine candidates become ready for approval, more studies may be needed to understand the outcomes of combining doses between the multiple available vaccine candidates. There are many potential benefits to being able to combine COVID-19 vaccine candidates, which is why scientists are eager for more data to evaluate this. Ramping up COVID-19 vaccine supplies and coordinating distribution remain a challenge, so being able to give vaccines based on availability could mean more people receive the vaccinations faster and more lives are saved. The U.K.'s deputy chief medical officer has said that there may be benefits to having data that could support more "flexible" vaccination programs, since there is currently an insufficient global supply of COVID-19 vaccines. Beyond the logistical benefits, there could potentially be immunological benefits of using two different vaccines to combat the same pathogen in certain cases. For COVID-19 vaccines that are given in two doses, the "prime" dose is followed by a "boost" dose to help stimulate and amplify the body's immune response, with the goal of developing immunological memory to protect against COVID-19 infections in the future. The strategy of using doses from different vaccines is known as "heterologous prime-boost." Some COVID-19 vaccine candidates, like the Russian Sputnik V, have even been designed to use this strategy with the first and second doses containing different viral components. With newer and faster-spreading variants of COVID-19 emerging around the world, some of which could be partially resistant to immune responses triggered by the vaccines, scientists are also planning to investigate whether combining different vaccines can help offer more protection. Multiple COVID-19 vaccine candidates have been developed in record speed to help combat the global pandemic. In order to take full advantage of every tool that is available for pandemic response, scientists are studying the potential of combining doses from different COVID-19 vaccine candidates. As more data becomes available, public health experts and policymakers will be able to make more informed decisions about "mixing and matching" COVID-19 vaccine doses.
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