If You're Over 50, This Vaccine Produces More Antibodies, New Study Says
Research shows the advantage of one COVID vaccine for older adults.
Older adults have been considered high-risk for the coronavirus since the beginning of the pandemic. Unfortunately, even though breakthrough infections are relatively uncommon, it appears as though older vaccinated people are still more vulnerable to serious illness if they get infected. According to the latest data from the Centers for Disease Control and Prevention (CDC), 70 percent of vaccinated individuals hospitalized for COVID as of Aug. 23 were 65 years or older. But there are certain factors that can influence how protected seniors are through vaccination, potentially reducing their risk for a serious breakthrough case of COVID.
A new study published Sept. 2 in the JAMA Network Open journal looked at antibody response according to age for those who received either of the mRNA vaccines. The researchers recruited more than 160 adults affiliated with the University of Virginia who had received two doses of either the Pfizer or Moderna vaccines, drawing their blood before and after the second shot.
According to the study, participants 50 years old or older produced higher levels of IgG antibodies when they received the Moderna vaccine instead of the Pfizer vaccine. The researchers found that after two shots, this age group produced 71.8 micrograms per milliliter worth of these binding antibodies with Moderna, compared to only 31.1 micrograms per milliliter with Pfizer.
When comparing the same vaccine by age, participants 50 years old or older who received the Pfizer vaccine had roughly a 50 percent lower level of binding antibodies than younger recipients. But with Moderna's vaccine, both younger and older recipients had the same antibody levels.
"We saw a difference with the Pfizer and Moderna vaccines, but most of the difference was when you looked at the older subjects," Jeffrey Wilson, MD, the principal investor of the study and an immunologist, told The Boston Globe. "There may be subgroups of the population that may be better served by getting one vaccine than another."
When comparing Moderna and Pfizer overall, the former also caused recipients to develop more antibodies. On average, people who received the Moderna vaccine developed 68.5 micrograms per milliliter worth of binding antibodies compared with 45.9 micrograms per milliliter with Pfizer. But this is not the first study to find that Moderna's vaccine could be generating significantly higher antibody levels than Pfizer's.
A recent study out of Belgium published Aug. 30 in the Journal of the American Medical Association compared the antibody response following vaccination with both Pfizer and Moderna, finding that Moderna produces twice as many antibodies. And another, published on Aug. 16 in JAMA Internal Medicine found similar results of higher IgG antibodies produced by Moderna.
Researchers for these studies say that one viable explanation is that Moderna's vaccine has a higher amount of the active ingredient, mRNA. Each dose of Moderna contains 100 micrograms of vaccine, while each Pfizer dose contains just 30 micrograms. Another theory is that the longer interval time for Moderna doses, which is four weeks instead of Pfizer's three weeks, might also contribute to the increase in antibodies.