Coronavirus: Fewer antibodies capable of neutralizing the virus after six weeks

More than six in 10 people infected with the novel coronavirus generated neutralizing antibodies just two weeks after the onset of symptoms of the disease, but this neutralizing capacity decreases after six weeks, according to researchers at the Centre de recherche du Centre hospitalier de l’Université de Montréal, (CRCHUM).

Canada Research chair in retroviral entry and professor at Université de Montréal, Andrés Finzi, said in a statement that “a few booster shots of the vaccine may be necessary to protect the population in the long term.”

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In a non-peer-reviewed study posted on the bioRxiv prepublication server, Finzi’s team evaluated the capacity to neutralize plasma — the liquid component of blood containing antibodies — one, two, three and six weeks after the onset of symptoms of the disease.

The team used plasma samples from 108 patients, healthy, infected or convalescent, provided by Héma-Québec and the Laboratoire de santé publique du Québec.

The researchers found that after three weeks, more than 90 per cent of those infected had antibodies that recognize one of the signatures of SARS-CoV-2, the glycoprotein S. After six weeks, it was 100 per cent.

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But not all antibodies have the same effectiveness: while some easily neutralize the virus, others do so only more timidly, if at all.

More studies would be needed to determine, for example, how long a person exposed to the virus a second time would be protected or whether protection requires the generation of neutralizing antibodies.