Both mRNA vaccines target COVID-19’s spike, involve two doses, at least currently, and have been widely effective. That hasn’t stopped inquiring minds from wondering whether there are some head-to-head differences in the real world.
IgG levels against the spike's regional binding domain (RBD) were measured 7 to 31 days after the second shot of BNT162b (Pfizer) and mRNA-1273 (Moderna). The picture tells the story.
- Both vaccines boosted IgG levels which were further increased by the second shot. Moderna’s vaccine produced more antibodies.
- The first dose produced equivalent antibodies in the under 50 crowd, but Moderna’s produced more in those over 50.
- Given the second dose, the vaccines produced equivalent amounts.
The researchers suggest two possible underlying explanations for the lower levels after the first vaccination. Older individuals have less robust immune systems, and Moderna’s dose is three times that of Pfizer. Both are arguments that could and may be used in pushing for a booster 3rd dose.
Source: Comparison of SARS-CoV-2 Antibody Response by Age Among Recipients of the BNT162b2 vs the mRNA-1273 Vaccine JAMA Network Open DOI: 10.1001/jamanetworkopen.2021.24331
