Pfizer and Moderna COVID-19 Vaccines Could Produce Years of Immunity

Two new studies show that mRNA COVID-19 vaccines may build lasting immunity against the virus months after inoculation. Researchers anticipate that this immune response will continue and people will not need a booster for years after their first two doses.

The studies—one of which was conducted by the Washington University School of Medicine and the other by Rockefeller University—followed people who had received two doses of either the Pfizer or the Moderna vaccines. 

Both vaccines employ mRNA technology, which has been effective against the COVID-19 variants currently in circulation. The success of these vaccines comes from their ability to produce antibodies and memory B cells that evolve in the body and respond to fight the virus, according to the studies. If new variants surface and the cells are unable to fight them off, an appropriately-timed booster may be necessary.

“For these special germinal center B cells to be persisting for that long, that's an indication that those cells are going to persist for much, much longer,” Jason Diaz, PhD, an assistant professor of integrated science, business, and technology at La Salle University who has studied mRNA vaccines, tells Verywell. “When B cells are persisting for that long after infection or vaccination, we have seen previously that they will persist, likely, for decades afterwards.”

Still, researchers can only be certain of the longevity of the immune response if they continue to monitor the vaccine recipients, he adds.

The production of B cells comes from the mRNA technology, which is different from traditional vaccine technology. The mRNA vaccines use genetic blueprints to build proteins to train the immune system to fight off the virus, while traditional vaccines insert a weakened or inactive virus into the body. The Johnson and Johnson vaccine does not use mRNA technology, and was not evaluated in the two studies. 

“The J&J vaccine is delivering DNA to your cells, not mRNA,” Diaz says. “You're still going to get a good response, but whether that's gonna persist for years or just for one or two years is unsure.”

Two doses of the Pfizer or Moderna vaccines are about 95% effective in preventing COVID-19, while one dose of Johnson & Johnson’s Janssen vaccine is about 66% effective, according to the Centers for Disease Control and Prevention (CDC).

Without an official study, researchers expect the Johnson & Johnson provides less immunity than the mRNA vaccines, but immunity levels could go up if people received a second dose, according to The New York Times.

The new studies, however, offer a sign of hope that the mRNA technology is working and the pandemic may eventually end.

“This study is just one more piece of evidence that keeps making me excited about this technology,” Diaz says. “[It] gives us hope that if we continue to vaccinate as much as possible and limit how much coronavirus can spread and mutate, we'll be able to close the chapter on this pandemic.”

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