COVID-19 antibodies could last at least three months, study suggests

Novel coronavirus (COVID-19) antibodies can last at least three months after a person becomes infected with SARS-CoV-2, the virus that causes COVID-19, according to a new study published in the journal Science Immunology.

Researchers from the Lunenfeld-Tanenbaum Research Institute at Sinai Health and the Temerty Faculty of Medicine at the University of Toronto used both saliva and blood samples from COVID-19 patients to measure and compare antibody levels for over three months post-symptom onset. The saliva assay was developed at the University of Toronto, while a team at the Lunenfeld-Tanenbaum Research Institute executed the serum assay, according to the study.

The researchers found that antibodies of the IgG class that bind to the SARS-CoV-2 spike protein are detectable for at least 115 days, representing the longest time interval measured, the study said. 

Most people who recover from COVID-19 develop immune agents in their blood called antibodies that are specific to the virus. These antibodies are useful in indicating who has been infected, regardless of whether they had symptoms or not, the researchers said.

The durability of the antibody response to SARS-CoV-2 has been debated in recent months. This study agrees with findings from immunologists in the U.S. who said the antibody response is longer lasting, according to the study. 

While the researchers said there is a lot they still don't know about antibody responses to SARS-CoV-2 infection, including how long the antibodies last beyond this period or what protection they afford against re-infection, they said this research could have broader implications in the development of an effective vaccine.

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