New research from the Icahn School of Medicine at Mount Sinai shows that COVID-19 survivors build strong immune responses after one vaccine dose. In fact, their immune response to the first vaccine dose is equal to—or in some cases even better than—the response to a second vaccine dose in someone who has not had COVID-19.
These significant new findings appear in a study led by Viviana Simon, MD, PhD, and Florian Krammer, PhD, which was published in a letter to the editor in the March 10, 2021, edition of The New England Journal of Medicine.
Viviana Simon, MD, PhD
“We believe that a single dose of the authorized mRNA vaccines (from Pfizer-BioNTech and Moderna) is sufficient for people who have already been infected by SARS-CoV-2,” the virus that causes COVID-19, says Dr. Simon, Professor of Microbiology, and Medicine (Infectious Diseases), at Icahn Mount Sinai. “Our study showed that the antibody response to the first vaccine dose in people with pre-existing immunity is equal to or even exceeds the response in uninfected people after the second dose.”
The study included 110 participants. After their first vaccine dose, COVID-19 survivors who were seropositive at the time of the dose generated antibody levels that were 10 to 45 times higher than their seronegative counterparts who had never been infected by SARS-CoV-2. Equally significant, antibody levels in seronegative individuals rose by a factor of three after their second vaccine dose, while seropositive individuals had no increase in their levels of antibodies after that dose.
Panel A shows the quantitative SARS-CoV-2 spike antibody titers or levels for 110 participants. (These were assessed by means of enzyme-linked immunosorbent assay and expressed as area under the curve [AUC].) Some participants with pre-existing immunity had antibody titers below detection (AUC of 1) at time point before vaccination. Panel B shows the relative frequency of vaccine-associated side effects after the first vaccine dose in 230 participants.
There were no substantial differences between the Pfizer-BioNTech and Moderna vaccines in the antibody responses they elicited, according to the researchers.
Florian Krammer, PhD
Mount Sinai’s team also observed that in an overlapping group of 230 participants, seropositive individuals experienced more intense—but well tolerated—physical reactions than seronegative individuals following their first doses of the vaccine. Interestingly, the frequency with which they reported fatigue, headaches, fever, chills, and muscle and joint pain after their first dose was similar to the responses among seronegative individuals after their second vaccine dose. Researchers say this is to be expected after the body recognizes the virus—or vaccine—and responds vigorously.
Drs. Simon and Krammer say their findings will require further investigation to determine whether these early differences in immune responses are maintained over a prolonged period of time. If the results hold up, they could influence a change in public policy that would require COVID-19 survivors to have only one dose of the authorized mRNA vaccines. According to Dr. Krammer, several European countries have already updated their policies based on these findings.
“If that approach were to translate into public health policy (that is more widely adopted), it could not only expand limited vaccine supplies, but control the more frequent and pronounced reactions to those vaccines experienced by COVID-19 survivors,” says Dr. Simon.