Moderna Inc.’s COVID-19 vaccine generated more than double the antibodies of a similar shot made by Pfizer Inc. and BioNTech SE in research that compared immune responses evoked by the two inoculations.
The study is one of the first to compare levels of antibodies produced by the two vaccines, which are thought to be one of the important components of the immune response. It didn’t examine whether the antibody differences led to a difference in efficacy over time between the two shots, which both were more than 90% effective in final-stage clinical trials
The research looked at antibody levels against the coronavirus spike protein in about 1600 workers at a major Belgium hospital system whose blood samples were analyzed 6 to 10 weeks after vaccination. The participants hadn’t been infected with the coronavirus before getting vaccinated. Levels among those who got two doses of the Moderna vaccine averaged 2,881 units per milliliter, compared with 1,108 units per milliliter among those who received two Pfizer doses.