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LONDON: Antibodies to the new coronavirus declined rapidly in the British population over the summer, a study found 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 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 that have forced local closures and restrictions in recent weeks.
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 decline, and we know that the antibodies themselves are quite protective,” Wendy Barclay, director 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 whose 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.
Imperial’s findings were published as a pre-print document and have not yet been peer-reviewed.
Barclay said the rapid decline in antibodies to infection does not necessarily have implications for the efficacy of vaccine candidates currently in clinical trials.
“A good vaccine can be better than natural immunity,” he said.
