According to the college article, London residents had the highest proportion of positive tests across the country, at around twice the national average. Health and care workers, ethnic minority groups, and those living in deprived areas and large households also had the greatest burden of past infection.
These findings, from the Real Time Assessment of Community Transmission, suggest a decline in the level of immunity in the population in the months following the first wave of the epidemic.
The REACT study used finger-prick testing to detect coronavirus antibodies in the blood, which, when present, indicates a person has been infected.
The study found that antibody prevalence declined from 6.0% to 4.8% and then to 4.4% over the three months of testing. The researchers observed this decline across all ages, but the smallest drop was in the youngest age group —18-24 — falling from 7.9% to 6.7% (14.9%); the largest was found in the oldest group — 75 and older — declining from 3.3% to 2.0% (39%).
Professor Helen Ward, one of the lead authors of the report said: “This very large study has shown that the proportion of people with detectable antibodies is falling over time. We don’t yet know whether this will leave these people at risk of reinfection with the virus that causes COVID-19, but it is essential that everyone continues to follow guidance to reduce the risk to themselves and others.”
Health Minister Lord Bethell said of the study: "It is also important that everyone knows what this means for them — this study will help in our fight against the virus, but testing positive for antibodies does not mean you are immune to COVID-19. Regardless of the result of an antibody test, everyone must continue to comply with government guidelines including social distancing, self-isolating and getting a test if you have symptoms and always remember Hands, Face, Space.”