Antibodies to the new coronavirus are declining rapidly among the British population over the summer, a study found Tuesday suggested that protection after infection may be short-lived and raises the prospect of a weakened immune system in the community.
Researchers at Imperial College London tracked antibody levels in the British population after the first wave of Covid-19 infections in March and April.
Their study found that antibody prevalence dropped from 6% of the population around the end of June to just 4.4% in September. This raises the prospect of a decline in the population̵
Although immunity to the new coronavirus is a complex and murky area and can be aided by T cells as well as B cells, which can stimulate the rapid production of antibodies after re-exposure to the virus, researchers say that experience with other coronaviruses suggests that immunity may not be permanent.
“We can see the antibodies and watch them decrease, and we know that the antibodies themselves are quite protective,” Wendy Barkley, head of infectious diseases at Imperial College London, told reporters.
“Regarding the evidence, I would say that from what we know about other coronaviruses, it appears that immunity decreases at the same rate as antibodies, and that this is an indication of declining immunity at the population level.”
Those whose Covid-19 was confirmed by a gold standard PCR test had a less pronounced drop in antibodies than people who were asymptomatic and unaware of their initial infection.
There was no change in the levels of antibodies observed in healthcare workers, probably due to repeated exposure to the virus.
Imperial’s findings have been published as pre-printed paper and have not yet been reviewed.
Barclay said the rapid decline in antibodies from infection does not necessarily have implications for the efficacy of vaccine applicants currently in clinical trials.
“A good vaccine can be better than natural immunity,” she said.