Since the coronavirus pandemic began, researchers have been tasked with answering an important question: For those who have recovered from a coronavirus infection, do COVID-19 antibodies offer protection from future infections, and for how long?
A study published Wednesday in the journal JAMA Internal Medicine suggests that those who have COVID-19 antibodies have a significantly lower risk of reinfection compared to those who do not have them.
Researchers from the National Cancer Institute and companies including LabCorp and Quest Diagnostics conducted an observational study, analyzing data on more than 3.2 million Americans who had undergone a COVID-19 antibody test between January and August 2020.
Just under 12% of those tested were found to be positive for coronavirus antibodies, while some 88% were negative for them. The researchers, using follow-up data, found that less than 1% — 0.3% to be exact — of those who had coronavirus antibodies tested positive for a COVID-19 infection at the 90-day mark.
Meanwhile, about 3% of those who did not test positive for antibodies later tested positive for COVID-19 for a second time, suggesting reinfection.
The study suggests that those who have coronavirus antibodies may be protected from reinfection up to 90 days, or about three months, and possibly beyond.
“In this cohort study, deidentified data from commercial laboratories suggest that the presence of antibodies to SARS-CoV-2 is associated with a reduced risk of having a subsequent positive NAAT results, which may be a proxy representing a new infection or may represent continued viral shedding depending on the context and timing. While this risk reduction was not seen in the first 30 days after an initial antibody test, it became pronounced after 30 days and progressively strengthened through the 90-day observation period and beyond,” the researchers concluded.
While the study was observational, and federal health experts have urged everyone — including those who have recovered from a coronavirus infection and may be offered some natural immunity— to receive the COVID-19 vaccine, the findings bolster past research done on this topic.
A comprehensive study published in November, for instance, determined that COVID-19 antibodies could last for at least six months or longer, perhaps a matter of years.