Two separate studies in Science Immunology document the persistence of SARS-CoV-2 antibodies in COVID-19 patients at least three months after symptom onset. Both studies suggest that longer-lasting immunoglobulin G (IgG) antibodies may hold promise as a tool to evaluate viral immune response. One study also demonstrates a correlation between blood and saliva antibody levels, suggesting that saliva could serve as an easier-to-collect alternative to blood testing, according to a news report from the Center for Infectious Disease Policy and Research (CIDRAP) at the University of Minnesota.
While the presence of COVID-19–specific antibodies—immune molecules generated by the body in response to a virus—has been demonstrated in infected patients, the durability of COVID-19 antibodies is not yet fully understood. Previous studies have shown antibodies diminishing to undetectable levels two months after infection in asymptomatic patients. The duration of antibody response is critical for tracking the spread of COVID-19, as well as to inform vaccine development.
In the first new study, researchers measured antibodies specific to the SARS-CoV-2 spike protein's receptor binding domain in the blood of 343 patients for up to 122 days after symptom onset, comparing antibody levels to those of 1,548 individuals sampled before the pandemic.
The second study found a similar duration of antibody response among 402 University of Toronto Hospital COVID-19 patients whose antibody responses were recorded from 3 to 115 days after onset. Researchers compared their responses with those from 339 pre-pandemic control patients.
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