The mRNA vaccine from Moderna Inc induces higher levels of antibodies against the coronavirus that causes COVID-19 than the similar vaccine from Pfizer Inc and partner BioNTech SE, Belgian researchers have found, although what this means for their efficacy is not clear.
Soon after receiving their second shot, the 688 healthcare workers who got Moderna’s vaccine had antibody levels roughly twice as high as the 959 who received the Pfizer/BioNTech product, regardless of their ages, doctors at a Belgian medical center reported.
This held true even after accounting for individual risk factors, and regardless of whether participants had previously been infected with the virus, the researchers reported on Monday in JAMA.
Antibodies are just one component of the immune system’s defenses, however. The study cannot determine whether one vaccine is more effective at preventing infection or illness, or whether the antibodies induced stay longer in the blood before disappearing. Those questions, and others, require further investigation, the researchers said.
