Coronavirus antibodies persist for at least nine months after infection: study

A study in northern Italy found coronavirus antibodies persisted at detectable levels for at least nine months after infection, regardless of symptomatic or asymptomatic disease progression, although results differ depending on the test used.

Researchers at Imperial College London and the University of Padua on Monday published results in Nature Communications, based on an analysis in Vo ‘, Italy, where a campaign of mass testing saw 86% (2 602 people) from the community tested in February / March and May. 2020, of which around 6% tested positive and were retested in November.

The results indicated that 98.8% of people positive for COVID had detectable levels of antibodies in November, and nearly 20% had increased levels or reactivity since May, suggesting potential reinfection. Scientists followed antibody levels through three tests made by Roche, DiaSorin and Abbott and found different rates of decay in antibody levels.

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“The May tests showed that 3.5% of the Vo ‘population had been exposed to the virus, although not all of these subjects were aware of their exposure given the large fraction of asymptomatic infections,” said the Professor Enrico Lavezzo of the University of Padua in a statement posted on EurekAlert.org on Monday.

“However, during the follow-up, which was done about nine months after the outbreak, we found that the antibodies were less abundant, so we must continue to monitor the persistence of the antibodies over longer periods.”

Other evidence suggested that the antibodies persist for at least six months after the initial infection, while another team found detectable levels of antibodies 11 months later, claiming that even a mild case of the coronavirus could leave them. people have lifelong protection against the virus.

In the ongoing study, lead author Dr Ilaria Dorigatti, senior lecturer at Imperial College London, said the team “found no evidence that antibody levels between infections Symptomatic and asymptomatic differ significantly, suggesting that the strength of the immune response does not depend on the symptoms and severity of the infection.

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She urged caution when comparing estimates of infection among populations that underwent different tests at various time intervals.

Further analysis of household contacts suggested a 1 in 4 chance that an infected person will pass the virus on to others, and a minority of infections generated a large number of secondary infections.

“It is clear that the epidemic is not over, neither in Italy nor abroad,” said Dorigatti. “In the future, I think it is of fundamental importance to continue to administer the first and second doses of vaccine as well as to strengthen surveillance, including contact tracing. Encourage caution and limit the risk of contracting SARS-CoV-2 will remain essential. “