This comes after studies published last month found that boosters may not be necessary for people who were previously infected with COVID-19 and later vaccinated, The New York Timesreported. For those who were previously infected and then vaccinated, the protections could last years.
The study did not investigate whether there would be similar effects with the Johnson & Johnson vaccine.
The scientists, led by Ali H. Ellebedy, PhD, of the Department of Pathology and Immunology at Washington University School of Medicine in St Louis, found that after a single dose of the Pfizer vaccine, immune cell responses, located in the germinal center of the lymph nodes, remained active longer than expected. This suggests that these mRNA vaccines may offer extended protection against the virus.
Forty-one people took part in this study, some of whom had recovered from COVID-19. The scientists studied lymph node samples of 14 of them.
The researchers also found the Moderna and Pfizer vaccines provide robust protection for at least 12 weeks after a second dose and could provide low-level protection for at least a year.
“The study shows that the germinal centers have prolonged B cell responses,” William Schaffner, MD, a professor of preventive medicine and infectious diseases at Vanderbilt University, tells WebMD. “The anticipation is that these memory cells are going to persist for a substantial period of time.”
Schaffner says that while the response of B cells -- a key to the immune system -- wasn’t very long, the study offers insight into the biology of what happens after someone receives an mRNA vaccine. But the findings should not lead to quick conclusions.
“It’s one thing to have this lab affirmation of biology of immune response,” Schaffner says. “It’s another thing to study the duration of the protection of substantial populations of people.”
He says the findings also add to current discussions of whether people who have been vaccinated will need booster shots.
“The two big issues are kind of addressed here,” Schaffner says. “One is what is the actual duration of protection that’s provided from initial immunization. The other is could there be variants that can evade this protection. Or the antibodies we create won’t specifically provide protections.”
He notes that there is optimism in the fact that neither of these issues has arisen, even 6 months into vaccine distributions.
“Studies like this suggest that it could be a year or longer,” Schaffner says. “That would be fabulous.”
But exactly how long immunity lasts remains a question.
“The authors are very careful not to make specific projections,” Schaffner says. “That would be very difficult.”
He says that while booster shots may be a popular topic of conversation, they should not be too much of a concern, even with current variants.
“The vaccines we do have offer pretty good protections for the variants that are active,” Schaffner says. “So there is no immediate need for a booster as of right now.”