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(CNN) -
There is new evidence connecting a positive covid-19 antibody test from a previous infection with a significantly lower risk of re-infection in the future.
A study published in the journal
JAMA Internal Medicine
on Wednesday found that people who tested positive for covid-19 antibodies had a lower risk of coronavirus infection compared to those who tested negative for antibodies.
“The study results basically show a 10-fold reduction, but I would have some caveats in this regard.
In other words, it could be an overestimation of the reduction.
It could be an underestimation of the reduction, ”said Dr. Douglas Lowy, senior deputy director of the National Cancer Institute, one of the study authors.
"For me, the big message is that there is a reduction," he said.
"The main conclusion is that a positive antibody (test) after a natural infection is associated with partial protection against a new infection," he added.
Lowy added that people who have recovered from COVID-19 should still get vaccinated when it is their turn.
Study details
The researchers - from the National Cancer Institute and the companies LabCorp, Quest Diagnostics, Aetion Inc., and HealthVerity - examined data from more than 3.2 million people in the United States who had had a COVID-19 antibody test this year. last between January and August.
Among those tested, 11.6% tested positive for covid-19 antibodies and 88.3% tested negative.
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In follow-up data, the researchers found that only 0.3% of those who tested positive for COVID-19 antibodies ended up testing positive for a coronavirus infection later, after 90%.
In contrast, 3% of those who tested negative for COVID-19 antibodies were later diagnosed with the infection during the same period.
The study is observational and suggests that there is an association between positive COVID-19 antibody test results and a lower risk of infection about 90 days later.
However, more research is needed to determine if there is a causal relationship and how long the protection of the antibodies can last.
Lowy said more research is also needed to determine the risk of reinfection with one of the emerging variants of the coronavirus.
Now that these worrying variants exist, what are the implications?
The short answer is we don't know, ”Lowy said.
He also stressed that people who tested positive for antibodies should get vaccinated against COVID-19.
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A key question: how long does antibody protection last?
It is already known that the majority of patients recovering from COVID-19 have antibodies and so far reinfection appears to be rare, but it is not yet clear "how long the antibody protection will last due to natural infection," wrote Dr. Mitchell Katz of the NYC Health + Hospitals health care system in an editorial that was published alongside 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.
"It is also unknown how long the antibody protection provided by vaccines will last," he wrote.
"Knowing how long antibody protection will last due to natural infection or vaccination is something that only time will tell," he added.
Antibodies