In a report published in the journal Immunity, researchers report that antibody responses induced by COVID-19 vaccines appear to be persistent, challenging the assumption that mRNA-based vaccine immunity wanes quickly.
“It is thought that mRNA-based vaccine-induced immunity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) wanes quickly, based mostly on short-term studies,” the study team wrote. “Here, we analyzed the kinetics and durability of the humoral responses to SARS-CoV-2 infection and vaccination using >8,000 longitudinal samples collected over a 3-year period in New York City. Upon primary immunization, participants with preexisting immunity mounted higher antibody responses faster and achieved higher steady-state antibody titers than naive individuals. Antibody kinetics were characterized by two phases: an initial rapid decay, followed by a stabilization phase with very slow decay.”
The study explains that booster vaccination “equalized the differences in antibody concentration between participants with and without hybrid immunity, but the peak antibody titers decreased with each successive antigen exposure. Breakthrough infections increased antibodies to similar titers as an additional vaccine dose in naive individuals.”
The authors emphasized that their study provides strong evidence that SARS-CoV-2 antibody responses are long-lasting, with initial waning followed by stabilization.
The Mount Sinai research team analyzed more than 8,000 samples collected over a 3-year period in New York City, examining how antibody responses to the virus’s spike protein changed after infections, during the primary immunization series, during monovalent and bivalent booster vaccination, and during breakthrough infections.
Among the findings was that primary immunization, participants with preexisting immunity—i.e., those who had previously been infected with the virus—mounted higher antibody responses faster and achieved higher steady-state antibody titers than patients who had not been previously infected.
The researchers suggest that changes in the virus that allow it to evade immunity, not waning immunity from vaccines, are the major reason for breakthrough infections.
“Ours is one of the longest-running COVID-19 studies out there,” said lead author Viviana Simon, MD, PhD, at Icahn Mount Sinai. Following the same group of people monthly over time is rare and powerful because you can compare immune responses on an individual level. SARS-CoV-2 continues to evolve, so this research is important to provide an understanding about the impact of new variants and new vaccine doses on a healthy immune system and to guide all of us to make the best choices to maintain protection against the virus that continues to circulate in our communities.”
The new analyses grew out of the Protection Associated with Rapid Immunity to SARS-CoV-2 (PARIS) study, an observational, longitudinal cohort of healthcare workers of the Mount Sinai Health System initiated in April 2020.
The PARIS study tracked individual antibody responses to vaccines based on the type of vaccine received and whether they were infected before receiving the first dose. It also enabled the development of a mathematical model that can be used to predict and characterize antibody responses of both individual people and populations.
“People have pandemic fatigue and vaccine uptake has slowed, especially after the vaccines started to be charged to insurance,” said coauthor Komal Srivastava, MS, Director of Strategy and Operation of the Mount Sinai Center for Vaccine Research and Pandemic Preparedness. “We were pleasantly surprised to see that the booster doses promoted a large antibody response regardless of a person’s personal infection history, so we are hopeful that our study findings will encourage people to get their vaccine boosters when eligible and to stay engaged in research. Our work also showcases the impact of viral evolution over time and why it’s critical to keep studies like this going, despite the pandemic fatigue.”
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