Study suggests that Covid-19 antibodies may later protect against reinfection

A study published in the journal JAMA Internal Medicine on Wednesday found that people who tested positive for Covid-19 antibodies had a reduced risk of coronavirus infection compared to those who tested negative for antibodies.

“The results of the study are basically a tenfold reduction, but I would have reservations about that. In other words, it could be an overestimation of the reduction. It could be an underestimation of the reduction,” said Dr. Douglas Lowy said. , chief deputy director of the National Cancer Institute, who was an author of the study.

Lowy added that people who have recovered from Covid-19 should still be vaccinated if it is their turn.

The researchers – from the National Cancer Institute and the companies LabCorp, Quest Diagnostics, Aetion Inc. and HealthVerity – examined data on more than 3.2 million people in the United States who completed a Covid-19 antibody test between January last year. August. Among those tested, 11.6% tested positive for Covid-19 antibodies and 88.3% negative.

In the follow-up data, the researchers found that only 0.3% of those who tested positive for Covid-19 antibodies tested positive for coronavirus infection later than 90 days. While 3% of those with negative Covid-19 antibody test results were diagnosed with coronavirus infection later in the same period.

Overall, the study is observational and suggests that there is a link between positive results from the Covid-19 antibody test and a lower risk of infection about 90 days later – but more research is needed to find a causal link. determine and for how long protection against antibodies. can hold.

Lowy said more research is also needed to determine the risk of re-infection by one of the emerging coronavirus variants.

“Now that there are these variants of concern, what are the implications there? The short answer is that we do not know,” Lowy said. He also stressed that people who tested positive for antibodies should still get vaccinated against Covid-19.

It is already known that most patients who recover from Covid-19 have antibodies, and that reinfection is rare so far – but it is still unclear for “how long antibody protection will last due to natural infection”, said Dr. Mitchell Katz of the NYC said. Health + Hospitals’ healthcare system wrote in an editorial published in conjunction with the new study in JAMA Internal Medicine.

“For this reason, vaccination against SARS-CoV-2 is recommended regardless of antibody status,” Katz wrote. SARS-CoV-2 is the name of the coronavirus that causes Covid-19.

“How long the antibody protection by vaccines will last is also unknown,” he wrote. “Knowing how long antibody protection will last due to natural infection or vaccination is just the time we will learn.”