Nicola Davis reports that the proportion of people in England with coronavirus antibodies dropped by more than a quarter in the space of three months, fuelling concerns over reinfection.
The findings come from the React-2 study, which is based on home finger-prick antibody test results from random participants across all 314 local authorities.
The first results, based on data from 100,000 people, were released in August, revealing that about 6% of the population of England had the antibodies – protective proteins produced in response to an infection – although the team say that could be a slight underestimate.
The new work – not yet peer-reviewed – extends this with more testing in two fresh cohorts, each yielding results from more than 100,000 adults.
The results reveal that just 4.4% of those tested in the most recent round, between 15 and 28 September, had detectable coronavirus antibodies.
Graham Cooke, co-author of the report and professor of infectious diseases at Imperial College London, said:
As a whole, these data suggest the possibility that decreasing population immunity will lead to an increased risk of reinfection as detectable antibodies decline in the population.