Study shows evidence of waning immunity to Covid-19

LONDON: Researchers in the UK have found that antibodies against Covid-19 declined rapidly in the hundreds of thousands of people across England.

According to CNN, the research team from Imperial College London, who sent out home finger-prick tests to more than 365,000 randomly selected people in England, found more than a 26 per cent decline in Covid-19 antibodies over just three months.

“We observe a significant decline in the proportion of the population with detectable antibodies over three rounds of national surveillance, using a self-administered lateral flow test, 12, 18 and 24 weeks after the first peak of infections in England,” the study authors were quoted as saying to CNN.

“This is consistent with evidence that immunity to seasonal coronaviruses declines over 6 to 12 months after infection and emerging data on SARS-CoV-2 that also detected a decrease over time in antibody levels in individuals followed in longitudinal studies,” they added.

At the beginning of the study, in June, six per cent of those who took the tests had IgG antibody responses to the coronavirus, they reported.

By September, just 4.4 per cent of them did. For health care workers, the rates stayed about the same.

Antibodies are the proteins the body naturally generates to fight infection. IgG is one type – the tests were not designed to detect other types of antibodies.

Other research teams have found that other types of antibodies may persist longer than IgG does.

The results also confirm earlier studies that showed that people who did not have symptoms of Covid-19 are likely to lose detectable antibodies sooner rather than those who had more severe infections.

The researchers also found that younger people who had recovered from Covid-19 had a slower loss of antibodies, compared to people older than 75 who had survived an infection.