The proportion of people in Britain with antibodies that protect against Covid-19 declined over the summer, according to research that adds to evidence that natural immunity can wane in a matter of months.
The number of people with antibodies fell by a quarter, from 6 per cent of the population in June to 4.4 per cent in September, according to a study of hundreds of thousands of people, one of the largest of its kind to date.
The results, from researchers at Imperial College London, are the latest sign that immunity to Covid-19 may be shortlived and cast further doubt on the idea that any population could develop herd immunity naturally.
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