ATLANTA — As the discussion regarding COVID-19 booster shots continues, 11Alive viewer Chris recently asked the VERIFY team to take a closer look at recent studies circulating online comparing the two mRNA vaccines: Pfizer and Moderna.
Does the Moderna COVID-19 vaccine produce more antibodies than Pfizer?
Two recent studies show the Moderna vaccine can produce a higher antibody level than Pfizer, but whether this new data is medically relevant, remains to be seen.
WHAT WE KNOW
A recent study from the University of Virginia School of Medicine sought to look at the differences between the Moderna and Pfizer COVID-19 vaccines.
"People have definitely been looking at Pfizer, and people have been looking at Moderna and the different vaccines, but there hasn't been as much head to head," Dr. Jeffrey Wilson, immunologist and part of the UVA research team, explained. "And so that was one of our objectives."
For the small study, researchers examined blood samples from 167 UVA employees who received the vaccines and found antibody levels in employees who got the Moderna vaccine were slightly higher than in recipients of Pfizer. According to Dr. Wilson, the biggest disparity was age-related.
"We could really see that the difference was more pronounced in older folks in terms of the difference between Pfizer and Moderna," he said.
The latter study looked at fully vaccinated Belgium healthcare workers and found double the amount of antibodies in those who received the Moderna vaccine than those fully vaccinated with Pfizer.
Yet, scientists behind both studies caution they only looked at certain antibody types, while the immune system is quite complex.
"Limitations of this study include the lack of data on cellular immunity and on neutralizing antibodies, as well as the specific focus on health care workers," researchers behind the Belgium study wrote. "Whether the observed difference in antibody level translates to a difference in the duration of protection,4 the protection against variants of concern, and the risk of transmission6 needs further investigation."
Experts, however, speculate the antibody level difference that was observed could be due to the difference in timing and dosing of the two mRNA vaccines. But again, whether such results are relevant to vaccine protection remains to be seen.
"I think we're going to verify that this is being true, because the Moderna probably does elicit a little bit higher antibody level, but the next really important question is: does it matter? Because if Pfizer is eliciting enough antibody to give strong protection," Dr. Wilson said, "Then, a little bit more antibody, maybe it matters, maybe it doesn't matter, and right now I don't think we know that."
Dr. Harry Heiman, a public health expert at Georgia State University who is unaffiliated with the studies, echoed the same.
"I think the first question that people need to kind of ask is, is there a relationship, is there a correlation between the level of these antibodies that you're measuring, and their protection against COVID?" Dr. Heiman said. "And the answer is nobody knows."
"It's important to do these studies, and to understand the differences," Dr. Heiman added. "But...from the perspective of the general public, I'm not sure that there's any relevance right now that should be important to them."
While the original goal of the vaccine rollout was to "get shots in arms as fast as possible," Dr. Wilson said said ongoing research can help inform whether a certain vaccine is better suited for a particular population, such as older adults. He said the UVA study can help inform that process.
"This is a small piece of a big puzzle," he said. "It doesn't give us the answer, but it helps help say we should be thinking about that."