Nearly 200 million Americans have received a COVID-19 vaccine, and as some approach the one-year anniversary of their immunization, questions remain about the vaccines’ long-term efficacy.
In a recent study published in the New England Journal of Medicine, researchers compared immune responses induced by the three vaccines over an eight-month follow-up period.
The study is from Beth Israel Deaconess Medical Center. One author is Dan H. Barouch, MD, Ph.D.
The team evaluated the 61 participants’ levels of various antibodies, T cells, and other immune products at two to four weeks following complete immunization—the time of peak immunity—to eight months after vaccination.
Among the people, 31 participants received the Pfizer vaccine, 22 received the Moderna vaccine and eight received the Johnson & Johnson vaccine.
The team found the two mRNA vaccines had high peak antibody responses that declined sharply by month six and declined further by month eight.
The single-shot Johnson & Johnson vaccine-induced lower initial antibody responses, but these responses were generally stable over time with minimal to no evidence of decline.
The researchers also found that Moderna elicited antibody responses which were generally higher and more durable than Pfizer. All three vaccines demonstrated broad cross-reactivity to variants of SARS-CoV-2, the virus that causes COVID-19.
They say the findings have important implications for understanding how vaccine immunity may wane over time; however, the precise immune responses necessary to confer protection against SARS-CoV-2 have not yet been determined.
Even though neutralizing antibody levels decline, stable T cell responses and non-neutralizing antibody functions at 8 months may explain how the vaccines continue to provide robust protection against severe COVID-19.
If you care about COVID, please read studies about heart problem that strongly increases risk of severe COVID-19 and death, and findings that aspirin and other drugs for inflammation could help prevent COVID-19 deaths.
For more information about COVID, please see recent studies about the cause of severe inflammation in COVID-19, and results showing that COVID-19 antibodies can prevent reinfection for up to 6 months.
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