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Health Desk articles

Can someone be infected with COVID-19 more than once?

We are still learning a lot about what kind of immunity a person has after being infected with COVID-19, and how long that immunity lasts. A a small number of people have reportedly become reinfected with virus following an initial infection and research is ongoing. According to the US Centers fo Disease Control and Prevention (CDC), "reinfection means a person was infected (got sick) once, recovered, and then later became infected again. Based on what we know from similar viruses, some reinfections are expected. We are still learning more about COVID-19." In a press conference on December 4th, 2020, the World Health Organization acknowledged emerging evidence that suggests that COVID-19 immunity is unlikely to be lifelong, which suggests reinfection may be possible. The most reliable way to measure immunity to COVID-19 is unclear, and, whether from infection or vaccination, scientists still do not know how long immunity to COVID-19 may last. Though reinfection has been documented, there are many ongoing questions about whether or not reinfection poses an ongoing risk, how common it is, and what kind of immunity to the virus people might obtain once they have been infected. Currently researchers believe that most people will be protected from reinfection for up to six months following infection, but research is ongoing. There are multiple pre-print studies with large participant groups that suggest immunity does last for up to six months but decreases over time. Antibodies decrease more quickly in young adults who have had an asymptomatic infection. Pre-print studies have also suggested that reinfection is possible. It is important to note that there is a shortage of peer-reviewed papers (so other scientific experts are not yet able to rigorously study the data or full results). It is also important to note that antibody levels may not be a strong indicator of immunity against the virus and likelihood of reinfection. To prevent infection, reinfection, and spread of COVID-19, experts recommend frequent hand washing, social distancing (6 feet/2 meters apart), avoidance of crowded areas (especially indoors), wearing a face mask (though the U.S. CDC now suggests wearing a cloth mask over a surgical mask or a high grade respirator), and staying home when you are sick or know that you have been exposed to COVID-19.

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.
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