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Antibodies from COVID-19 infection only last a few months: study

Coronavirus outbreak: Fewer antibodies capable of neutralizing the virus after six weeks, researchers say
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. Global's Anne Leclair spoke with Canada Research chair in retroviral entry and professor at Université de Montréal, Dr. Andrés Finzi.

Levels of an antibody found in recovered COVID-19 patients fell sharply in two to three months after infection for both symptomatic and asymptomatic patients, according to a Chinese study, raising questions about the length of any immunity against the novel coronavirus.

The research, published in Nature Medicine on June 18, highlights the risks of using COVID-19 ‘immunity passports’ and supports the prolonged use of public health interventions such as social distancing and isolating high-risk groups, researchers said.

Health authorities in some countries such as Germany are debating the ethics and practicalities of allowing people who test positive for antibodies to move more freely than others who don’t.

Read more: Fewer antibodies capable of neutralizing the coronavirus after six weeks

The research, which studied 37 symptomatic patients and 37 asymptomatic patients, found that of those who tested positive for the presence of the IgG antibody, one of the main types of antibodies induced after infection, over 90% showed sharp declines in 2-3 months.

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The median percentage decrease was more than 70% for both symptomatic and asymptomatic patients.

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For neutralising serum antibodies, the median percentage of decrease for symptomatic individuals was 11.7%, while for asymptomatic individuals it was 8.3%.

The study was conducted by researchers at Chongqing Medical University, a branch of the Chinese Center for Disease Control and Prevention and other institutes.

Read more: People develop protective antibodies after having COVID-19, but how long do they last?

Jin Dong-Yan, a virology professor at the University of Hong Kong who was not part of the research group, said the study does not negate the possibility that other parts of the immune system could offer protection.

Some cells memorize how to cope with a virus when first infected and can muster effective protection if there is a second round of infection, he said. Scientists are still investigating whether this mechanism works for the new coronavirus.

“The finding in this paper doesn’t mean the sky is falling,” he said, also noting that number of patients studied was small.