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By Alistair Smout
LONDON (Reuters) – Antibodies to the new coronavirus declined rapidly in the British population over the summer, a study found on Tuesday, suggesting that protection after infection may not be long-lasting and increases the possibility of waning immunity in the community.
Scientists at Imperial College London have tracked antibody levels in the British population following the first wave of COVID-19 infections in March and April.
Their study found that the prevalence of antibodies dropped by a quarter, from 6% of the population in late June to just 4.4% in September. That raises the possibility of a decline in the population’s immunity ahead of a second wave of infections in recent weeks that has forced local closures and restrictions.
Although immunity to the new coronavirus is a complex and cloudy area, and can be assisted by T cells, as well as B cells that can stimulate rapid antibody production after re-exposure to the virus, the researchers said the experience of other coronaviruses suggested immunity may not last long.
“We can see the antibodies and we can see them decrease and we know that the antibodies by themselves are quite protective,” Wendy Barclay, head of the Department of Infectious Diseases at Imperial College London, told reporters.
“On the balance of the evidence, I would say that with what we know about other coronaviruses, it would appear that immunity decreases at the same rate as antibodies decrease, and this is an indication of waning immunity at the population level.”
Those for whom COVID-19 was confirmed with a gold standard PCR test had a less pronounced decline in antibodies, compared to people who had been asymptomatic and were unaware of their original infection.
There were no changes in antibody levels seen in healthcare workers, possibly due to repeated exposure to the virus.
The study supports findings from similar surveys in Germany that found that the vast majority of people did not have COVID-19 antibodies, even in the hot spots of the disease, and that the antibodies could disappear in those who do.
World Health Organization spokesman Tarik Jasarevic said the uncertainty about how long immunity would last and the fact that most people had never had antibodies to the coronavirus in the first place showed the need to break the chains. of transmission.
“Acquiring this herd immunity simply by letting the virus pass through the population is not really an option,” he told a UN conference in Geneva.
The Imperial study, based on a survey of 365,000 randomly selected adults, was published as a pre-printed article and has not yet been peer-reviewed.
The rapid decline in antibodies did not necessarily have implications for the efficacy of vaccine candidates currently in clinical trials, Imperial’s Barclay said.
“A good vaccine can be better than natural immunity,” he said.
(Report by Alistair Smout; Additional report by Stephanie Nebehay in Geneva; Editing by Bill Berkrot and Bernadette Baum)
