COVID-19 Antibodies Last at Least Three Months after Infection

The COVID-19 caused by SARS-CoV-2 is now raging around the world. In a new study, researchers from the University of Toronto and the Lonefeld-Talenbaum Research Institute at Sinai Health used saliva and blood samples from COVID-19 patients to measure and compare the level of antibodies for more than three months post-symptom onset. They found that after a person is infected with SARS-CoV-2, antibodies against the virus can last for at least three months. The relevant research results were published in the journal Science Immunology.

These investigators found that IgG antibodies that bind to the SARS-CoV-2 spike protein (S protein) can be detected in at least 115 days, which is the longest time interval ever measured. This study also showed for the first time that these antibodies can also be detectable in saliva.

The co-corresponding author of the paper, Jennifer Gommerman, PhD, said that their research shows IgG antibodies against this viral spike protein are more durable in blood and saliva, and saliva may be used as an as an alternative for antibody test— although saliva is not as sensitive as serum, it is easy to collect.

The saliva assay was developed at the University of Toronto, and a research team led by Anne-Claude Gingras, also a professor of molecular genetics at the University of Toronto, performed the serum test. Gingras expressed that the LTRI platform for detection of antibodies in serum, or blood, is incredibly robust and well suited for assessing the prevalence of infection within the community. “This is another tool that can help us better understand and even overcome this virus.” Gingras added.

Most people who have recovered from COVID-19 have virus-specific antibodies in their blood. These antibodies can be used to indicate who has been infected, whether they have symptoms or not.The persistence of the antibody response to SARS-CoV-2 has been debated in recent months. A study published earlier in the journal Nature Medicine showed that for some people who were infected with the virus but did not show symptoms, the antibodies can disappear after two months.

Although these investigators admit that there are still many things they don’t know about the antibody response to SARS-CoV-2 infection, including how long the antibodies can last after this period, or how these antibodies protect against re-infection, this study could have broader implications for the development of effective vaccines.

Gommerman also concluded that their study suggests “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.”

Reference:

1. Isho, B., et al..Persistence of serum and saliva antibody responses to SARS-CoV-2 spike antigens in COVID-19 patients. Science immunology, (2020):5(52).