Moderna’s COVID-19 Vaccine Found More Effective Than Pfizer’s Against Delta Variant

Moderna’s COVID-19 vaccine may be more effective than the Pfizer-BioNTech vaccine at protecting against variants of the coronavirus that causes COVID-19, two “preprint,” nonpeer-reviewed studies suggest.

One study, conducted by the Mayo Clinic and Cambridge, Mass.-based data analytics company Nference, looked at more than 50,000 individuals who passed through the Mayo Clinic Health System from January to July and received one of the two vaccines or who were unvaccinated.

The found that both vaccines were “highly effective” during this study period against SARS-CoV-2 infection COVID-19-associated hospitalization. But in July, when the Delta variant was predominant, the vaccines’ effectiveness against infection had dropped to 76 percent for the Moderna vaccine, mRNA-1273, and to 42 percent for the Pfizer-BioNTech vaccine, BNT162b2.

In data from five states, mRNA-1273 “conferred a two-fold risk reduction against breakthrough infection compared to BNT162b2,” the Mayo Clinical research found. And in Florida, “the risk of infection in July after full vaccination with mRNA-1273 was about 60 percent lower than after full vaccination with BNT162b2.”

“Our observational study highlights that while both mRNA COVID-19 vaccines strongly protect against infection and severe disease, further evaluation of mechanisms underlying differences in their effectiveness, such as dosing regimens and vaccine composition, are warranted,” the researchers said.

A separate, much smaller Canadian study examined 198 long-term care home residents in Ontario, finding that those who received the Moderna vaccine mounted stronger total and neutralizing antibody responses than those administered BNT162b2. Two to four weeks after the second dose, “residents administered BNT162b2 produced 3.89-fold fewer neutralizing antibodies than those who received mRNA-1273.”

Read the preprint articles here: bit.ly/3s4Mk9J and bit.ly/3fTlOer. — Martin Berman-Gorvine