The Moderna COVID-19 vaccine appears to generate a stronger immune response than the Pfizer-BioNTech shot, which has a similar formulation, a study published Thursday by JAMA Network Open found.
This is particularly true in adults age 50 and older, based on levels of antibodies, or immune cells that fight off viruses, the data showed.
However, older adults produce fewer antibodies following vaccination with either shot than those ages 32 to 49.
Whether this immune response translates into increased protection against infection and severe disease from COVID-19 “remains to be seen,” the researchers said.
“Our study suggests that the Moderna vaccine elicits higher levels of binding antibodies than the vaccine from Pfizer-BioNTech,” study co-author Dr. Jeffrey Wilson told UPI in an email.
“In our study, the difference in antibody levels between the two vaccines was most pronounced in relatively older subjects,” said Wilson, an assistant professor of allergy and immunology at the University of Virginia in Charlottesville.
A study published Monday by JAMA found that the Moderna vaccine prompts the immune system to produce twice as many antibodies as the Pfizer-BioNTech shot.
But both vaccines were more than 90% effective against early strains of the coronavirus, and may offer up to 70% protection against the Delta variant, which is the predominant one in circulation across the United States, according to the Centers for Disease Control and Prevention.
For this study, Wilson and his colleagues compared antibody levels in 167 adults ages 32 to 57 who received either Moderna or Pfizer-BioNTech vaccines and were fully vaccinated, meaning they had received both doses of the two-shot products.
Sixty-three of the study participants were age 50 or older and 120 of them were women.
Among study participants, six had been infected with COVID-19 before vaccination, according to the researchers.
Before receiving the second dose, participants vaccinated with the Moderna shot had three times as many antibodies against the coronavirus as those given the Pfizer-BioNTech vaccine.
After the second dose, antibody levels were about 50% higher in those given the Moderna vaccine compared with those who received Pfizer-BioNTech.
In those older than age 50, antibody levels were nearly seven times higher following the first dose of the Moderna vaccine compared with the Pfizer-BioNTech shots.
After the second dose, those given the Moderna shot had 60% higher antibody levels than those who received Pfizer-BioNTech.
Younger adults given the Pfizer-BioNTech vaccine had five times as many antibodies following the first dose than those age 50 years and older, the data showed.
“Our study represents a small piece of a big puzzle and it has to be acknowledged that antibodies, particularly binding antibodies, only represent one part of the immune response against viruses,” Wilson said.
“On a population basis, Pfizer-BioNTech and Moderna have both proven very effective in protecting against COVID-19 [and they] represent our safest and fastest way out of the pandemic,” he said.