TORONTO -- A new peer-reviewed study suggests that mRNA vaccines like the ones made by Pfizer-BioNTech and Moderna could offer years of protection against COVID-19.

Researchers based at the Washington University School of Medicine in St. Louis, Mo. published their findings on Monday in the journal Nature. They looked at immune responses in 14 individuals who received both doses of the Pfizer vaccine, specifically focusing on the “germinal centres.”

Germinal centres refer to sites where antibody cells can train to better recognize and combat viruses. These centres are vital to antibody production and are created as a result of a viral infection or a vaccination.

“Germinal centres are where our immune memories are formed. And the longer we have a germinal centre, the stronger and more durable our immunity will be because there’s a fierce selection process happening there, and only the best immune cells survive,” said senior study author Ali Ellebedy in a news release.

The research team extracted lymph node cell samples from the participants at three, four, five and seven weeks after the first dose from all 14 participants. They also obtained more samples from 10 of the participants 15 weeks after the first dose, or 12 weeks after the second dose.

Three weeks after the first dose, all 14 participants had germinal centres producing antibodies. The team found the germinal centres continued to be active even 12 weeks after the second dose.

“We found that germinal centres were still going strong 15 weeks after the vaccine’s first dose. We’re still monitoring the germinal centres, and they’re not declining,” Ellebedy said, calling these results “truly remarkable.”

This is the first study conducted with human participants to provide evidence of the persistence of these germinal centres as a result of an mRNA vaccine for the SARS-CoV-2 virus. Previous studies looking into germinal centres relied on animal test subjects.

In April, both Pfizer and Moderna stated that their vaccines would last at least six months based on data from early trials, although those studies did not investigate the body’s immune responses. The CEO of Moderna has stated that a booster shot may be necessary in the future.

It’s still unclear exactly how long immunity from mRNA vaccines could last, but the researchers say that these results are a “positive indicator” of the long-term effectiveness of these vaccines.

“This is evidence of a really robust immune response,” said co-senior author Rachel Presti in a news release. “Your immune system uses germinal centres to perfect the antibodies so they can bind well and last as long as possible. The antibodies in the blood are the end result of the process, but the germinal centre is where it is happening.”