ST. LOUIS COUNTY, Mo. — The Moderna and Pfizer vaccines will likely provide lasting immunity to COVID-19, according to findings from a new study by the Washington University School of Medicine in St. Louis.
Both vaccines were authorized for emergency use and employed mRNA technology, which has never been used before in FDA-approved vaccines. Both vaccines performed well in clinical trials, and both have been widely credited with reducing disease, but there have been concerns over how long immunity induced by the new vaccine technology will last, WashU said in a news release.
Now, a study from WashU School of Medicine researchers, published June 28 in the journal Nature, found evidence that the Moderna and Pfizer vaccines induce an immune response that is "both strong and potentially long-lasting," the release said.
According to the study, those who received the Pfizer vaccine four months prior still had "germinal centers" in their lymph nodes producing immune cells against SARS-CoV-2, the virus that causes COVID-19.
"Germinal centers, which form as the result of natural infection or vaccination, are boot camps for immune cells, a place where inexperienced cells are trained to better recognize the enemy and weapons are sharpened. A better germinal center response may equal a better vaccine," the release stated.
The study also found that vaccination led to high levels of neutralizing antibodies effective against three virus variants, including the beta variant from South Africa.
In April, both Pfizer and Moderna reported their vaccines provided at least six months of protection, based on tracking whether vaccinated people had contracted COVID-19. Other groups have looked at antibody levels in the blood to determine that the vaccine provides at least months of protection. But no one had yet looked at how immune response was developing in the body.
Senior author Dr. Ali Ellebedy, PhD, an associate professor of pathology and immunology of medicine and of molecular microbiology, said in the release that germinal centers are the key to a persistent, protective immune response.
“Germinal centers are where our immune memories are formed. And the longer we have a germinal center, 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," she said. "We found that germinal centers were still going strong 15 weeks after the vaccine’s first dose. We’re still monitoring the germinal centers, and they’re not declining; in some people, they’re still ongoing. This is truly remarkable.”
Many scientists suspect that the quality of the germinal centers induced by different vaccines may be the key to why some offer lifetime protection and others require regular boosters, the university said.
The study examined cells extracted from the germinal centers in lymph nodes in the armpit. The cells were extracted from 14 people who received the Pfizer vaccine, at three weeks after the first dose, then at weeks four, five and seven. Ten participants gave additional samples 15 weeks after the first dose, and none of the participants contracted COVID-19.
They also took blood samples from 41 people who had received the Pfizer vaccine, including eight who had previously contracted the virus that caused COVID-19. They found that those who had been previously infected already had antibodies in their blood before the first dose, but those levels then shot up quickly and peaked higher than the levels of people who hadn't been infected.
“We didn’t set out to compare the effectiveness of vaccination in people with and without a history of infection, but when we looked at the data we could see an effect,” said co-first author Dr. Jane O'Halloran, PhD. “If you’ve already been infected and then you get vaccinated, you get a boost to your antibody levels. The vaccine clearly adds benefit, even in the context of prior infection, which is why we recommend that people who have had COVID-19 get the vaccine.”
To read the full release, click here.