Moderna's COVID-19 vaccine creates antibody levels more than twice as high as Pfizer's vaccine, according to a study published Aug. 30 in JAMA.
The study examined 2,499 healthcare workers in Belgium who had been fully vaccinated with either of the vaccines. Among workers without previous infection, Moderna recipients' antibody levels were 2,881 units per milliliter and Pfizer recipients' antibody levels were 1,108 units per milliliter.
The researchers said that the stronger immune response observed in Moderna recipients could be a result of the longer interval between their first and second shots. Moderna recipients waited four weeks, but Pfizer recipients waited three. They also noted Moderna's vaccine has a higher concentration of mRNA content.
The observed difference in antibody levels correlates with a difference in the vaccines' duration of protection, but more research is needed to determine which vaccine offers stronger protection against coronavirus variants and the risk of transmission.