Coronavirus antibodies can last at least 3 months after a person is originally infected with coronavirus disease 2019 (COVID-19), according to new research published in Science Immunology.

Most patients who recover from COVID-19 develop antibodies in the blood that are specific to the virus. According to the investigators, these immune agents can be useful in indicating who has been infected, regardless of whether or not they were symptomatic. The durability of the antibodies has been debated, after an earlier study suggested that they can disappear after 2 months for some individuals who were asymptomatic.

Investigators used both saliva and blood samples from COVID-19 patients to measure and compare antibody levels for more than 3 months following their symptom onset. They found that antibodies of the immunoglobulin G (IgG) class that bind to the severe acute respiratory coronavirus 2 (SARS-CoV-2) spike protein are detectable for at least 115 days.

This was the longest time interval measured and is the first study to show that these antibodies are also detectable in saliva.

“Our study shows that IgG antibodies against the spike protein of the virus are relatively durable in both blood and saliva,” said Jennifer Gommerman, PhD, leader of the saliva testing effort, in a press release. “Our study suggests saliva may serve as an alternative for antibody testing. While saliva is not as sensitive as serum, it is easy to collect.”

These new study results are in line with findings from leading immunologists in the United States, who have described the antibody response as longer lasting. Although the investigators said there is much more to learn, including what protection the antibodies offer against re-infection, this research could have broad implications in the development of a vaccine.

“This study suggests that if a vaccine is properly designed, it has the potential to induce a durable antibody response that can help protect the vaccinated person against the virus that causes COVID-19,” Gommerman concluded.

REFERENCE
Coronavirus antibodies last at least three months after infection, U of T study finds [news release]. University of Toronto; October 8, 2020. https://www.utoronto.ca/news/coronavirus-antibodies-last-least-three-months-after-infection-u-t-study-finds. Accessed October 13, 2020.