Scientists at Imperial College London tracked antibody levels in the British population following the first wave of COVID-19 infections in March and April. According to a preprint of the study posted on Tuesday,
The Real-Time Assessment of Community Transmission (REACT) study used finger-prick testing to detect coronavirus antibodies in the blood. If antibodies were present – this indicated that a person has been previously infected with the virus.
The testing kits, called Lateral Flow Tests, detect antibodies above a particular concentration in the blood and do not measure the amount of antibodies in a particular person, according to Imperial College.
Londoners had the highest number of positive tests across the country, at around twice the national average in the first wave of the virus. Healthcare workers, minority groups, and those living in deprived areas and large households also showed a greater proportion of past infection.
The study found that antibody prevalence fell by a quarter, from six percent of the population around the end of June to just 4.4 percent in September. “Immunity is waning quite rapidly, we’re only three months after our first [round of tests] and we’re already showing a 26 percent decline in antibodies,” said Prof Helen Ward, one of the researchers, reports the BBC.
Immunity to the coronavirus is complex, and still being studied and may be assisted by T cells as well as B cells, which can stimulate the quick production of antibodies following re-exposure to the virus, according to the study. Based on their experience with other coronaviruses, the scientists suggest immunity may not be long-lasting, reports CBC Canada.
“We can see the antibodies and we can see them declining and we know that antibodies on their own are quite protective,” Wendy Barclay, head of the Department of Infectious Disease at Imperial College London told reporters.
“On the balance of evidence I would say, with what we know for other coronaviruses, it would look as if immunity declines away at the same rate as antibodies decline away, and that this is an indication of waning immunity at the population level.”
As for the effectiveness of vaccines, the researchers say a vaccine may be more effective than a real infection in offering protection against the coronavirus. One of the researchers, Prof Graham Cooke, said: “The big picture is after the first wave, the great majority of the country didn’t have evidence of protective immunity. The need for a vaccine is still very large, the data doesn’t change that.”
