The possibility of coronavirus reinfection has been a concern since the first reports of people getting sick again started appearing in 2020 – while many around the world were still isolated. But, so far, there is relatively little data on how widespread this phenomenon is.
The first large-scale investigation to address this issue was published in The Lancet this week, and found that the vast majority of the people who took COVID-19 are in fact protected from getting it again – for at least six months. However, people aged 65 and over are much more likely than younger individuals to have recurrent infection.
The researchers analyzed data from Denmark’s national testing program COVID-19, which offered free PCR tests to about 4 million people living in the country. Overall, they found that a very small percentage of the population – 0.65% – suffered reinfection.
For those 65 and under, obtaining the coronavirus once provided about 80% protection against reinfection. But for people aged 65 and over, it provided only about 47% protection against the use of COVID-19 again, further highlighting just how dangerous this disease can be for older adults.
“As the elderly are also more likely to experience severe symptoms of illness and, unfortunately, to die, our findings make it clear how important it is to implement policies to protect the elderly during the pandemic,” Steen Ethelberg, author of the study at the Statens Serum Institut in Denmark , said in a statement. “In light of what is at stake, the results emphasize the importance of people adhering to the measures implemented to keep themselves and others safe – even if they have already had COVID-19.”
“In view of what is at stake, the results emphasize the importance of people adhering to the measures implemented to keep themselves and others safe”.
– Steen Ethelberg, researcher at the Statens Serum Institut in Denmark
What this study means to us (and the future of the pandemic)
In general, this news is positive, but it also highlights the need for continuous surveillance. Many factors can still play a potential role in illness.
The emergence of different variants is one of them. Coronavirus reinfection has become a particular concern in recent months, as new variants have begun to circulate around the world.
A vaccine study in South Africa – where a variant is circulating that experts fear is more contagious and could make current vaccines less effective – found new infections in 2% of people who had previously been infected with a different variant of the coronavirus.
The large new study carried out in Denmark did not examine the role of variants in reinfection, given the time frame of the research. Therefore, it offers no clue as to whether the variants make it more likely that someone will take the COVID-19 more than once.
Previous case studies of people who have been reinfected were worrisome because they suggested that it was possible to get sick a second time. This was the case for a healthy 25-year-old man in Nevada who tested positive for COVID-19 last spring, recovered and fell ill again. He needed hospitalization a second time. But even when these first reports emerged and attracted significant media coverage, the researchers were careful to point out the rarity of this result.
As the new study on reinfection has not been carried out in the United States, it is not clear whether the results apply in the same way here. But in general, the researchers are optimistic that most people who take COVID-19 will not have reinfection shortly thereafter. And they continue to study immunity, both after infection and after vaccination. It is not clear at this point how long immunity lasts after a person receives the COVID-19 vaccine.
All of this reinforces the continuing need for basic preventive measures, even with coronavirus cases beginning to decline across the country.
The Centers for Disease Control and Prevention recommend that people who have taken COVID-19 be vaccinated as soon as they become available, largely because there is a small chance of being infected again if they come into contact with the virus.
Continued use of the mask is also essential, as qThe doubts remain about the extent to which those who have recovered from COVID-19 are able to pass it on to others if they are exposed again. In addition, wearing a mask helps to decrease the small chance that an individual will catch the virus more than once.
Earlier this month, the CDC released new guidelines saying that fully vaccinated Americans can safely meet indoors without wearing masks or social distance, providing a promising glimpse of how restrictions are likely to ease as more injections go for more weapons. But for now, it is a race against the clock to ensure that millions of Americans are immunized while the variants continue to spread.
Experts are still learning about COVID-19. The information in this story is what was known or available at the time of publication, but the orientation may change as scientists discover more about the virus. Check the Centers for Disease Control and Prevention for the most up-to-date recommendations.