Not All mRNA Vaccines Are the Same: Subtle Antibody Differences After COVID-19 Boosters

Since the start of the COVID-19 pandemic, mRNA vaccines have played a key role in protecting people from severe disease. While both BioNTech/Pfizer’s BNT162b2 and Moderna’s mRNA-1273 vaccines offer strong protection, our new study shows that they don’t elicit identical immune responses.

Together with colleagues from the Institute of Tropical Medicine (Dr. Meral Esen, Alex S. Siebner) and the NMI (Dr. Alex Dulovic), we analyzed how antibody subclasses shift after a booster vaccination. We focused on IgG antibodies — especially the lesser-known IgG2 and IgG4 types, which differ from IgG1 and IgG3 in their ability to activate the immune system. We found that both vaccines increased overall IgG levels, but BNT162b2 induced significantly higher levels of IgG2 and IgG4 than mRNA-1273. These subtle shifts might matter, as IgG subclasses play different roles in immune signaling and virus neutralization.

Understanding such differences could help tailor future vaccination strategies and improve long-term protection against evolving viruses.

You can find the full study here.

Image: IgG antibody (Source: Laboratoires Servier; Creative Commons Attribution-Share Alike 3.0)