Patient samples to be tested for SARS-CoV-2 antibodies. Credit: Centers for Disease Control and Prevention/James Gathany
More than 90 percent of people who recovered at home from mild and moderate cases of COVID-19 produced a robust and possibly protective level of antibodies that remained relatively stable for at least five months, according to a new study by researchers at the Icahn School of Medicine at Mount Sinai.
The study, published in the latest issue of Science, was one of the largest of its kind ever conducted. It included 30,082 individuals who were screened at the Mount Sinai Health System. The patients, of diverse ages and ethnic and socioeconomic backgrounds, presented with a range of symptoms—from those who had almost none to those who spent several weeks in bed.
The findings are important because they provide irrefutable evidence that the body, in most cases, responds to COVID-19 by producing neutralizing antibodies that characterize a protective immune response, which does not quickly fade. Also significant, the findings apply to the majority of people who actually get COVID-19—those with mild to moderate cases.
This latest data confirms the strength and reliability of Mount Sinai’s ELISA antibody test, which was the first to detect the presence of antibodies to SARS-CoV-2, the virus that causes COVID-19 and the first to measure the amount of antibodies present in the blood.
“We will continue to follow a subset of these individuals over time to see how long these antibodies last, but so far the data are encouraging in terms of possible protection and the potential of vaccines working,” says the study’s first author, Ania Wajnberg, MD, Associate Professor of Medicine at the Icahn School of Medicine at Mount Sinai. “You can see that at five months the antibodies declined slightly, which is expected in a virus like this. But they certainly did not rapidly decline to zero, as had been reported in some press articles. That is not what we’re finding.”
Dr. Wajnberg says Mount Sinai’s leading microbiologists are working toward a better understanding of the precise level of antibody titers that would actually prevent an individual from getting sick from COVID-19 again. “That is going to take time,” she says. “We don’t want people with antibodies to think they can ignore guidelines around social distancing, masks, etc. But this is encouraging data.” Dr. Wajnberg says the team did not delve into the reasons why a very small segment of the patients did not mount a robust immune response, though this is seen in different viruses and may be an area of future research.
The study authors wrote that “Although we cannot provide conclusive evidence that these antibody responses protect from reinfection, we believe it is very likely that they will decrease the odds of getting reinfected and may attenuate the disease in the case of a breakthrough infection.”
“Vaccines generally work by eliciting an antibody response, and ongoing vaccine trials may also contribute to our understanding about the protective effects and duration of SARS CoV 2 antibodies,” says the study’s corresponding author Carlos Cordon-Cardo, MD, PhD, the Irene Heinz Given and John LaPorte Given Professor and Chair in Pathology, at the Icahn School of Medicine at Mount Sinai.