Public health experts
in service of journalism.

What do we know about pregnancy and COVID-19?

If a pregnant person becomes infected with COVID-19 there is a higher chance they will require hospitalization and suffer more serious symptoms of the disease. In early November 2020, the U.S. Centers for Disease Control and Prevention (U.S. CDC) released a report on 400,000 women between the ages of 15 and 44 with symptomatic COVID-19 which found that admission to the intensive care unit (ICU), invasive ventilation, extracorporeal membrane oxygenation, and death were more likely in pregnant women than in non-pregnant women. The report includes that increased risk for admission to the ICU was "particularly notable" among Asian and Native Hawaiian/Pacific Islander pregnant women, and that both disproportionate risk for SARS-CoV-2 infection and higher risk for death was observed for pregnant Hispanic women. Highlighting the racial/ethic disparities, the report states that "regardless of pregnancy status, non-Hispanic Black women experienced a disproportionate number of deaths." This report adds to the current knowledge around increased risks related to COVID-19 for pregnant women, particularly pregnant women of color, and suggests that pregnant women should be counseled about increased risks of severe illness or death related to COVID-19 as well as measures to prevent infection in their families. Preterm birth has also been associated with COVID-19, according to another report released by the U.S. CDC in early November 2020. The U.S. CDC encourages people to take preventive measures while pregnant and to seek prenatal care throughout pregnancy. If a person is infectious during labor, it is possible for them to spread the virus to the baby. Outside of the U.S., the World Health Organization (WHO) has reported that emerging international research suggests pregnant women with COVID-19 are more likely to need intensive care if severely ill, and more likely to give birth prematurely. The latest findings also suggest that pregnant women with COVID-19 who have pre-existing medical conditions, who are older, or who are overweight are more likely to suffer severe health complications due to COVID-19.

Why should we all be wearing masks?

In combination with hand washing and social distancing measures, it is important to wear masks to prevent the spread of COVID-19 because the virus spreads primarily through respiratory droplets released when people speak, cough, sneeze or sing. Some infected people may not appear ill or may develop symptoms at a later time, but they can still spread the virus without symptoms. Masks prevent people from spreading the virus to others, especially when we can't be 6 ft / 2m apart. A recent lab study conducted by the U.S. Centers for Disease Control and Prevention found that by wearing two masks, people's protection against virus in the air (also called aerosolized particles) was dramatically increased. The study demonstrated that wearing any kind of mask provides significantly more protection against infectious aerosols than not wearing a mask. Additionally, when dummies who wore two masks - like cloth face masks over surgical masks - were exposed to infectious aerosols, their level of protection was roughly 92%. (The group now recommends fitting a cloth mask over a medical procedure mask, and knotting the ear loops of a medical procedure mask and then tucking in and flattening the extra material close to the face. However, the U.S. CDC does not recommend wearing two disposable masks at one time or another mask on top of a KN95 or N95 mask.) Cloth masks primarily protect people in close proximity to the person wearing the mask by trapping droplets that are released from the wearer. Cloth masks can also protect the wearer by filtering out some virus particles trying to enter. Medical masks (N95 or FFP2) filter virus particles from entering more effectively than cloth masks and are designed to protect the wearer. Supplies of those are limited and generally reserved for doctors.

What do we know so far about the COVID-19 vaccines during or before pregnancy and breastfeeding?

None of the three leading vaccine manufacturers (Pfizer, Moderna, and AstraZeneca) have reported data about the COVID-19 vaccine on knowingly pregnant or breastfeeding individuals. As a result, we have a limited understanding of how effective the three leading vaccines are for pregnant and breastfeeding people, and if there are specific risks.  Given this lack of data, some regulators and public health entities have not included pregnant people in their vaccine recommendations to the public with some specifically warning pregnant individuals against taking the vaccine. The WHO was one of these entities until Friday, January 29. Previously their guidance said that the vaccine was "currently not recommended" for pregnant women unless they are at high risk of exposure.  While their guidance, in practice, is still similar, recommending pregnant people with comorbidities or at high risk of exposure may be vaccinated in consult with doctors, they’ve directly noted that we “don’t have any specific reason to believe there will be specific risks that would outweigh the benefits of vaccination for pregnant women.” Until there is more data on COVID-19 vaccines and pregnancy, this trend of mixed guidance across different regulatory bodies and countries is likely to if and as vaccines continue to get approved.  Pregnant people who do receive a vaccine may be able to produce an immunity to the virus from the vaccine that can cross the placenta which would help keep the baby protected after birth. Regarding safety, however, when you receive an mRNA vaccine for COVID-19 you expel the mRNA particles from your body within days, so if pregnant it’s unlikely to cross the placenta and impact the baby. The process for collecting this data will involve analyzing the impacts of the vaccines on individuals who receive a vaccination and later discover that they’re pregnant. Countries are coordinating internal reporting and monitoring systems to record and track this information.  The clinical trials had some participants enrolled who didn’t know they were pregnant at the time of vaccination, but there were not enough of those cases to have enough data for definitive conclusions. For example, in Phase 2/3 of the Pfizer and BioNTech vaccine study, 23 pregnancies were reported through November 14, 2020. Twelve were in the vaccine group and 11 in the placebo group. Two adverse events occurred in pregnancies in the placebo group, including miscarriage. These initial data do not raise concern for lack of vaccine safety in pregnancy and breastfeeding, but more data is needed to safely recommend the use of this vaccine by pregnant and breastfeeding individuals. The U.S. FDA also recommended in June 2020 that the pharmaceutical companies developing COVID-19 vaccines first conduct developmental and reproductive toxicity (DART) studies of their vaccine before enrolling pregnant or breastfeeding people, or women not actively avoiding pregnancy, in their trials.  Pfizer and BioNTech have directly stated that they are conducting DART studies, which will provide us with more information on the safety and efficacy of their vaccine for pregnant and breastfeeding individuals. On December 13, the American College of Obstetricians and Gynecologists released a position paper advocating for the inclusion of pregnant women in vaccine rollouts and not waiting for further data collection. While the group advocates for obtaining informed consent from pregnant and lactating women receiving the vaccine, they feel the benefits of protection outweigh the risks. The U.S. Centers for Disease Control and Prevention (CDC), the American College of Obstetricians and Gynecologists (ACOG), and the Society for Maternal-Fetal Medicine support the use of new mRNA COVID-19 vaccines in pregnant and breastfeeding individuals when they become eligible for receiving the vaccine. As of January 26, 2021, the World Health Organization also supports pregnant and breastfeeding women receiving the Moderna mRNA vaccine if they choose. Before more data is available, it is best for pregnant and breastfeeding individuals to speak with their doctors about the best way to proceed. While it is unlikely that a doctor would recommend a pregnant or breastfeeding person get vaccinated before more data is available unless they were high risk, every risk profile is different and is worth discussing with a care provider.

What are COVID-19 risks for cancer survivors (5+ years)?

The majority of cancer survivors, who have been cancer-free for at least five years, are likely to have normal immune system functions and are not at an increased risk for COVID-19. However, every body is different so every cancer survivor should speak with a doctor who knows their full medical history and can discuss their personal risks with them. For some cancer survivors, their previous treatments might impact their risk of getting COVID-19 or having a severe form of the disease, as these treatments can have long term effects on the immune system and cause the survivor to have preexisting conditions that may put them at a higher risk for viral infection. For example, patients who have undergone a bone marrow transplant (also known as a 'stem cell transplant') might not regain a completely functional immune system as the transplant depletes their white blood cell system (which the body then replaces). Some patients who have undergone bone marrow transplants are no longer immune to illnesses they had become immune to before the procedure. These patients can be at risk for a number of infections, including COVID-19, but the longer it has been since treatment, the more time your body's immune system has had to improve. Despite not having a higher risk of becoming infected with the virus than the general population, it should be noted that cancer survivors do have a higher risk of complications if they become infected with COVID-19. This group is also more likely to be hospitalized if they are infected, compared to people who have never had cancer before. To protect themselves from the virus, just like the general population, cancer survivors should use protective measures like wearing cloth masks over surgical masks, maintaining at least six feet of distance, staying home when they can, and washing hands thoroughly and often.

What do we know about new strains of this virus that is more infectious than the first strains?

Scientists are working to better understand the new variants (or versions) of the COVID-19 virus, how they spread, if vaccines will be effective, if the new variants are detectable by viral tests, and whether the variants cause mild or severe disease. Information about new variants of COVID-19 is changing quickly. According to the US Centers for Disease Control and Prevention, there is no evidence that the new COVID-19 variants cause more severe illness or increased risk of death. However, there is some evidence that suggests that one mutation (D614G) may spread more quickly than other variants. Viruses constantly change as they reproduce in order to keep spreading into more cells. These changes are called "viral mutations." Mutations create a new, updated version of the virus, which we call a "strain" or "variant" (though other similar words include "lineage" and "mutant"). These variants may have different properties than previous versions of the virus and may allow the virus to infect more people or may cause more severe illness. Many variants of COVID-19 have been documented globally, and scientists are continuing to monitor the virus as it changes and spreads around the world. To prevent the spread of COVID-19, international health agencies and the public health community continue to encourage the everyone to wear face masks (the U.S. Centers for Disease Control and Prevention now recommend wearing a cloth mask over a surgical mask or individual KN95/N95 masks), practice social distancing (maintaining 6 feet/2 meters physical distance), avoid crowds especially in indoor areas, and practice frequent hand washing with soap and warm water. 

Does wearing a mask protect the mask wearer?

Wearing a face mask helps prevent the spread of COVID-19 in two ways: It protects the person wearing a mask from being exposed to the virus and protects the people around them from being exposed to the virus. When a person talks, coughs, sneezes, or even breathes, they are exposing the people around them to what is in their body through the spread of small drops of liquid, called respiratory droplets, and even smaller, drier particles that float in the air. These bigger droplets carry saliva, mucus, and other germs (like the disease that causes the COVID-19 virus) which fall to surfaces while the smaller particles tend to stay in the air for a period of time. When people inhale these droplets through their mouths, noses, or eyes or touch their face after touching a surface where droplets fell, they are exposing themselves to COVID-19 and other germs exhaled by people their area. Wearing a face mask can reduce the amount of those particles that are inhaled through the mouth and nose, and can help stop people from touching their faces. Research shows that masks help stop germs from getting out into common spaces while also reducing the amount of germs inhaled by masks wearers, which can help reduce the chances of more severe disease. It is still important to note that though masks can be highly effective at preventing the spread of the virus, it also depends on the quality of the mask, the amount of layers it has, and how many people are wearing them in a specific area. This is why continuing to follow prevention protocols like social distancing and hand washing is still important. The U.S. Centers for Disease Control and Prevention now recommends fitting a cloth mask over a medical procedure mask, and knotting the ear loops of a medical procedure mask and then tucking in and flattening the extra material close to the face. However, the U.S. CDC does not recommend wearing two disposable masks at one time or another mask on top of a KN95 or N95 mask.

Can the virus be transmitted through the air?

According to the World Health Organization (WHO), the virus that causes COVID-19 is primarily spread through respiratory droplets (little spit droplets that fly out when a person sneezes, coughs or talks). Respiratory droplets can infect other people who are nearby, or indirectly infect others when they touch a surface contaminated with infected droplets. After an open letter by scientists in July 2020, the WHO now acknowledges the possibility of airborne transmission, which is caused by smaller and lighter 'droplet nuclei' (residuals of respiratory droplets from infected people) that can remain in the air for longer periods of time and remain infectious over long distances. Experts are looking at previous data from China to see whether the virus may spread through the air or through vents via airborne transmission. While a few lab-based studies have found that the virus can be present in the air for up to three hours, these studies did not assess if the virus is viable to infect anyone else. Recently, a research study published in Nature found viral contamination in air samples from patients isolated at a medical center, which supports the use of airborne isolation precautions in caring for COVID-19 cases. A few studies have also looked into how airborne transmission may have played a role in certain outbreaks, such as the one in the Diamond Princess cruise ship. One of these studies in pre-print found that it was likely that a combination of both close-range (respiratory droplet) transmission and long-range (airborne) transmission contributed similarly to disease progression aboard the ship. Thus far, the WHO still claims that evidence points to close person-to-person respiratory droplet transmission as the primary mode of COVID-19 transmission. However, experts warn that there is significant reason to believe airborne transmission is happening. The U.S. Centers for Disease Control and Prevention (CDC) now provides infection control recommendations for airborne transmission as well as respiratory droplet transmission. Definitive studies may take a long time to alter the body of evidence in the coming weeks and months, but proactive prevention measures such as universal use of masks (the U.S. CDC recommends wearing a cloth mask over a surgical mask for increased protection) could save lives in the meantime.

What do we know so far about face masks and their ability to prevent COVID-19?

According to the World Health Organization (WHO), wearing masks is part of an overall strategy to suppress the transmission of COVID-19, along with maintaining at least 2 meters (6 feet) distance and frequently washing your hands. A recent study conducted by the U.S. Centers for Disease Control and Prevention found that by wearing two masks, people's protection against the virus in the air dramatically increased. The study demonstrated that wearing any kind of mask provides significantly more protection against infectious COVID-19 aerosols than not wearing a mask. When dummies wearing two masks - like cloth face masks over surgical masks - were exposed to infectious aerosols, their level of protection was roughly 92%. The CDC now recommends fitting a cloth mask over a medical procedure mask, and knotting the ear loops of a medical procedure mask and then tucking in and flattening the extra material close to the face. However, the U.S. CDC does not recommend wearing two disposable masks at one time or another mask on top of a KN95 or N95 mask. There are generally two kinds of face masks that are available: medical masks and non-medical (or fabric) masks. Medical masks can protect people from getting infected as well as prevent people who are infected from spreading disease to others. Therefore, WHO recommends medical masks to be worn by health workers, care givers of patients infected with COVID-19, anyone who has mild symptoms of COVID-19, people with other health conditions which make them more susceptible to COVID-19, as well as people who are 60 years or older because they have a higher risk of getting infected with COVID-19. The WHO advises that non-medical masks should be worn in areas where there is high transmission of COVID-19, crowded places where at least 2 meters (6 feet) physical distancing is not possible, on public transport, in shops and other closed areas. COVID-19 can spread from people without symptoms, as they may not know that they are infected but are equally capable of spreading the virus. Hence, masks should be worn in public settings. The U.S. CDC warns that masks with exhalation valves or vents may not help prevent the spread of COVID-19 from the person wearing such a mask to others, therefore these masks should not be used for that purpose. The U.S. CDC also does not recommend face shields as substitutes for masks because of the large gaps below and alongside the face. Ideally, face shields should be used in combination with face masks. Wearing a face mask protects others from you when you cough, sneeze, talk, or just breathe, particularly indoors or when standing close to someone. Face masks also protect the wearer by preventing people from touching their mouth and nose, as well as reducing the amount of virus inhaled from other people nearby and reducing the risks of severe illness. In addition to social distancing measures (maintaining 6 feet or 2 meters between people), face masks are recommended to prevent the spread of COVID-19, even in hot climates. There is no evidence that surgical masks or cloth masks lower oxygen levels at all. It is important to use a mask that allows you to breathe comfortably while talking and walking and that fits well on your face. For safety, there are exceptions to wearing masks for children under the age of 2, for people with certain medical conditions or who have trouble breathing, and for anyone who is unconscious or unable to remove the mask without assistance. Mask wearing is a fundamental element of pandemic response for respiratory illnesses because masks act as a physical barrier from the release of infectious respiratory droplets that may come from your mouth or nose when you speak, sing, sneeze or cough.

What do we know about the Moderna vaccine so far?

The Moderna vaccine is being developed and produced by Moderna, Inc. and is a genetic mRNA vaccine (mRNA-1273) currently in ongoing Phase 3 clinical trials in the U.S. and a Phase 1/2 trial in Japan (announced January 21, 2021). This vaccine is approved for emergency use in the US (December 18, 2020), Canada (December 23, 2020), Israel (January 4, 2021), the European Union (January 6, 2021), the United Kingdom (January 8, 2021) and Switzerland (January 12, 2021). Here's a breakdown of everything you need to know so far about this vaccine's development. **Collaborators:** Moderna is collaborating with Biomedical Advanced Research and Development Authority and the National Institute of Allergy and Infectious Diseases (NIAID) on vaccine development and testing for the vaccine. **Latest information on how well the vaccine works:** Primary efficacy analysis data from the Phase 3 trial was published on November 30, 2020 and further peer-reviewed analysis was published on December 30, 2020. In both papers, the experimental COVID-19 vaccine was reported to have 94.1% efficacy. Protection against severe COVID-19 was reported at 100%. The study recorded a total of 196 infections among the 30,420 trial participants who received either the vaccine or a placebo (injections of saltwater). Of the 196 infections, 11 occurred among those who received the experimental (mRNA-1273) vaccine, and 185 infections occurred among those who did not receive the experimental vaccine (participants in the placebo group). Of the 30 severe cases of COVID-19 reported in the study, all were in the placebo group. There has been one COVID-19-related death in the study, which occurred in the placebo group. The results published in late November and late December are consistent with the first interim analysis conducted during the study (announced on November 16th, 2020) that reported efficacy of 94.5%. In a "Letter to the Editor" published in the New England Journal of Medicine on December 3, 2020, Moderna shared interim analysis findings from their Phase 1 trial that suggested that at "day 119" (119 days following a patient's first vaccine dose; 90 days after the second vaccine dose), binding and neutralizing antibody titers remained high in Phase 1 patients across age groups. In other words, the results suggested ongoing immunity, although precise levels for protection against COVID-19 have not yet been established. On January 25, 2021, Moderna announced the submission of a preprint study with results from an in vitro (laboratory-based) study suggesting the vaccine protects against new COVID-19 variants (B.1.1.7 first identified in the United Kingdom and B.1.351 first identified in the Republic of South Africa). The press release states that the vaccine "produced neutralizing titers [neutralizing antibodies] against all key emerging variants tested." However, the level of immunity against the B.1.351 variant was far less than the protection provided against earlier variants. To provide additional protection, Moderna plans to test another booster (injection) of the mRNA-1273 vaccine to see if immunity can be increased. Moderna is also beginning a preclinical study and a US-based Phase 1 trial of a new vaccine (mRNA-1273.351) specifically aimed at increasing immunity against the new variant by boosting strain-specific spike proteins. **Distribution timeline:** Applications for US FDA Emergency Use Authorization and Conditional Marketing Authorization (CMA) with the European Medicines Agency (EMA) were filed on November 30th, 2020. Safety and efficacy data was reviewed by the U.S. regulators an an Emergency Use Authorization was issued on December 18, 2020. Additional international approvals and distribution plans are further detailed in the following sections. **Approvals:** This vaccine is approved for emergency or interim use in individuals 18 years of age and older in the US (United States Food and Drug Administration)(December 18, 2020), Canada (Health Canada) (December 23, 2020), Israel (Israel's Ministry of Health)(January 4, 2021), the European Union (European Medicines Agency) (January 6, 2021), the United Kingdom (Medicines and Healthcare Products Regulatory Agency)(January 8, 2021), Switzerland (SwissMedic) (January 12, 2021), Singapore (Singapore Health Sciences Authority)(February 3, 2021), Qatar (Qatar Ministry of Public Health)(February 11, 2021). Additional authorizations are currently under review in other countries and by the World Health Organization. On January 26, 2021, the World Health Organization (WHO) Strategic Advisory Group of Experts issued interim recommendations for the use of the Moderna vaccine for people over 18 years of age. The group of experts concluded that "the known and potential benefits of mRNA-1273 outweigh the known and potential risks." Moderna is working with the WHO to obtain Emergency Use Listing (EUL) which would support wider access to the vaccine. **Distribution plan: **As of January 26th, 2021, Moderna has supplied approximately 30.4 million doses to the US government, and additional doses have been supplied to Canada, the UK and the EU. Moderna expects to supply 100 million doses to the US in the first quarter of 2021 (200 million total doses by the end of the second quarter and 300 million total doses by the end of the third quarter). In total, the company plans to manufacture 600 million doses globally in 2021, though it is continuing to invest with the goal of supplying 1 billion doses during 2021. Pending approval in Japan, Moderna has said that they plan to distribute 50 million doses in the first half of 2021. **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, in 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. 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 dosages 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. **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 once it 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 100 micrograms each into their upper arm muscle. The injections are given 28 days apart. If approved, researchers expect that the same dosage and schedule will be prescribed to the public. **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 Moderna vaccine can be stored in a standard refrigerator temperature range (2 to 8 degrees Celsius or 36 to 46 degrees Fahrenheit) for up to 30 days. The vaccine can also be kept in long-term storage at a standard freezer temperature (-20 degrees Celsius or -4 degrees Fahrenheit) for up to six months. Maintaining these storage temperatures is already possible across vaccine distribution channels. **Preclinical testing:** Before testing could begin on humans, the trial vaccine was tested on primates. Vaccine doses of 10 micrograms or 100 micrograms of the experimental vaccine were tested. On July 28, 2020, results were published and showed that the vaccine was protective against COVID-19. The vaccine was then permitted to advance to clinical trials in humans. **Phase 1 trial:** The first patient dose of mRNA-1273 was given on March 16, 2020 and results from the Phase 1 trial were published on July 14, 2020. The Phase 1 trial included 45 participants, between age 18 and 55, who received two vaccine doses each, 28 days apart. Participants were divided into 3 groups (of 15 each) to test vaccine doses: 25 micrograms (two doses of 25 micrograms each given 28 days apart), 100 micrograms (two doses of 100 micrograms each given 28 days apart), and 250 micrograms (one dose). By day 43 of the trial, researchers observed immune responses in all participants that could reduce the ability of COVID-19 to infect people by 80% or more. By day 57, participants who received 100 microgram doses of the vaccine had average levels of neutralizing antibodies (special proteins that disable viruses in the body) that were about twice the average levels found in patients who have recovered from COVID-19. On day 119 (119 days following the first vaccine dose; 90 days after the second vaccine dose), binding and neutralizing antibody titers remained high in Phase 1 patients across age groups. These titers suggest ongoing immunity, though precise levels for protection against COVID-19 have not yet been established yet. **Phase 2 trial:** Phase 2 approval was given on May 6th, 2020, and the Phase 2 trials started on May 29th, 2020. Phase 2 evaluated the two doses of 50 micrograms (given as two injections of 50 micrograms each) and 100 micrograms (given as two injections of 100 micrograms each). On June 11th, 2020, recruitment of participants was completed with a total of 300 participants between 18 and 55 years of age (50 total participants were over 55 years of age). On September 29th, 2020, Phase 2 findings were published and examined the immune responses for the vaccine in 40 older adults at different doses. The study examined two different vaccine doses (25 micrograms and 100 micrograms given in two doses each, 28 days apart) and found that the higher dose (100 micrograms) produced a greater antibody titer (immune) response in the older adult population. **Phase 1/2 trial: **On January 21, 2021, Moderna announced that a new combined Phase 1/2 study of 200 adult patients was being launched with Takeda Pharmaceuticals in Japan. Similar to prior studies, the study will evaluate the safety and immune response to two doses (100 micrograms each) of the mRNA-1273 vaccine given 28 days apart. Participants will be monitored for 12 months following the second vaccine. **Phase 3 trial:** This clinical study was registered as a randomized, placebo controlled trial (participants are selected for participation and randomly assigned to either receive the experimental vaccine or a placebo injection) on July 14th, 2020, and the study began on July 27, 2020 in study centers across the US. The total Phase 3 study enrollment was 30,420 participants age 18 and older (15,210 in the study group and the same number in the placebo group). On October 22, 2020 the company announced that recruitment was complete, and that 25,650 participants had already received two shots. 37% of study participants were from Communities of Color (>11,000 total with >6,000 who identify as Hispanic or LatinX, >3,000 who identify as Black or African American), and 42% were from populations considered high risk (7,000 Americans over the age of 65, and 5,000 who are under the age of 65 but have high-risk chronic diseases including diabetes, severe obesity, and cardiac disease that put them at higher risk of COVID-19). During the study, 96% of the study participants received both injections. Data collection from the Phase 3 trial is ongoing and will continue for two years; efficacy results are noted in the findings section above with current a efficacy of 94.1% (as published in the Efficacy and Safety of the mRNA-1273 SARS-CoV-2 Vaccine paper in the _New England Journal of Medicine_ on December 30, 2020). Efficacy results as reported were consistent across age, race and ethnicity, and gender. **Reported side effects and safety concerns:** No safety concerns have been reported in the Phase 3 study, and most side effects have been mild to moderate in severity. Severe concerns that have occurred in >2% of cases include injection site pain (reported by 86% or participants), fatigue, muscle aches and headache. In the Phase 1 trial, side effects including fatigue, chills, headache, muscle aches, and pain at the injection site were commonly reported, particularly after the second vaccine dose. In the early phases of research, participants who received the highest vaccine dose (250 micrograms) had more severe side effects than those in the other experimental groups. The most commonly reported severe symptoms included fatigue, fever (39-40 degrees C), and chills (significant, prevents daily activities). **Special populations:** On December 2, 2020, Moderna registered a new Phase 2/3 (combined phases) randomized, placebo controlled study with plans to enroll 3,000 healthy adolescents between 12 and <18 years of age from across the US. On December 10, 2020, Moderna announced that the first participants had received the experimental vaccine. Using the same dosing schedule as adults (two injections of 100 micrograms each given 28 days apart), the study aims to evaluate the safety and efficacy of the vaccine (including the type of side effects participants experience and the frequency of those events). The estimated study completion date is June 30, 2022. Though studies are planned, the mRNA-1273 vaccine has not yet been tested on children under 12 years of age, pregnant or lactating women, or other special groups (e.g. immunocompromised patients). **Other relevant notes:** N/A

What do we know about 2008 references to SARS-CoV-2 and SARS-CoV-3?

SARS-CoV-2, the virus that causes COVID-19, emerged in late 2019 and caused a global pandemic starting in early 2020. Following the current scientific naming convention, there has been no virus identified as SARS-CoV-3 as of early 2021. In 2008, a study was published by Chinese scientists funded by the European Commission as part of the Sino-European Project on SARS Diagnostics and Antivirals (SEPSDA). The study used the terms SARS-CoV1, SARS-CoV2, and SARS-CoV3. These numbered SARS-CoV terms refer to gene fragments of SARS-CoV-1, the virus that causes severe acute respiratory syndrome (SARS). The 2008 study focuses on a method of packaging an RNA sequence that could reduce labor costs. It is unrelated to the SARS-CoV-2 virus. SARS-CoV-1, originally referred to as simply SARS-CoV, was first identified during the SARS outbreaks of 2002-2004. SARS-CoV-2, originally referred to as 2019-nCoV, because it was a novel coronavirus that emerged in 2019, is a different virus from SARS-CoV-1. In a scientific consensus statement published by Nature in 2020, SARS-CoV-2 was renamed after being recognized as a sister to other respiratory syndrome-related coronaviruses, including SARS. The recognition took place based on phylogeny (the study of evolutionary relationships between biological entities), taxonomy and established practice. SARS-CoV-1 and SARS-CoV-2, while related, are different viruses and just two of many coronaviruses (named for crown-like spikes on the surfaces) in the RNA virus family of Coronaviridae.

Health information in your inbox, every other week

Success! An email has been sent to you to confirm your subscription.
Oops! Something went wrong while submitting the form.