Covid-19: ‘Getting virus doesn’t make one immune to reinfection’

Covid-19 antibodies wane fast among people who have been infected with the coronavirus, a study has found.

This could explain increased cases of re-infection being reported, even as researchers continue to accelerate the development of a vaccine.

A study published last week showed that there was a 26 percent decline in Covid-19 antibodies among UK residents in a period of three months.

The researchers said they observed a decline in the number of people with detectable antibodies after observing more than 365,000 randomly selected people in England in three rounds.

“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,” stated the researchers.

According to the study published by Imperial College London and Ipsos MORI, six percent of those who took tests in June had antibody responses to the virus. But by September, during the start of the second wave, only 4.4 of the adults who participated in the study had the antibodies.

Antibodies are generated when a person gets infected to fight against the infection. The researchers found that younger people lost the antibodies slower compared to people aged over 75 who did not die from Covid-19. Earlier studies showed that asymptomatic people were likely to lose the IgG antibodies faster compared to symptomatic cases.

Studies are still continuing to establish how long a recovered person can be re-infected by Covid-19.

But antibodies are not the only line of defence against an infection. Speaking with the Nation in an earlier interview, Dr Ambrose Angweyu, the Head of Epidemiology and Demography at the Kemri-Wellcome Trust Research Programme, said T Cells — a pre-existing (adaptive) immune system — could also contribute to immunity against the virus.