Levels of an antibody found in recovered COVID-19 patients fall sharply in 2-3 months after infection for both symptomatic and asymptomatic patients.

This is the main conclusion of a recent Chinese study, published in Nature Medicine.
The research work raises questions about the length of any immunity against the novel coronavirus.

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

The research 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, Reuters reports.

Sharp declines of antibodies in 2 – 3 months

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

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

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.