PITTSBURGH (KDKA) – What happens to antibodies against the novel coronavirus over time?
The higher the levels your body makes in response to infection, and the longer they last, the more protected you are.
“The higher chances you’re immune to that infection, which is, you won’t get it again,” Allegheny Health Network Infectious Diseases physician Dr. Nitin Bhanot explains.
A British study sheds some insight about how long these immune system proteins hang around.
“Immunologists did say that we don’t think the immunity, or the protection, will be very long-lasting with COVID-19. And so these studies are kind of proving the same concept,” Dr. Bhanot says.
There were 365,000 randomly selected people in England who did finger prick tests at 12, 18 and 24 weeks after the first peak of infections.
There were 6% who had antibodies in early June, compared to only 4.4% in late September — a 26% drop.
“It does tell you what the seroprevalence is in a population that has had a lot of COVID infections,” says Dr. Bhanot. At this rate of seroprevalence, or positive antibody tests, “we can’t rely on infections to provide that herd immunity.”
The largest declines between the first and last tests were among those who did not have symptoms, and those older than 75.
“People should not have that false sense of security that ‘I had the disease, I have an antibody and I’m immune to COVID-19 for life.’ That probably is not true,” Dr. Bhanot says, “If the antibodies wean off after a few months, people are at risk for reinfection.”
This could have implications for an eventual vaccine: “Would we need more than one vaccine shot? Would we need it frequently? Probably yes. Time will tell.”
But there is still hope for durable immunization. The body has another pathway to immunity.
“There’s another immunity called T cell immunity, so whether that will be different and how would that factor in is still to be known,” says Dr. Bhanot. “I think the vaccine studies would help with answering that question.”
The study from the Imperial College of London is awaiting peer review.
An earlier study from Iceland showed antibodies lasted 4 months. More studies and longer studies will help to answer how long antibodies persist.