Researchers from Switzerland report that the timing of the second dose of mRNA vaccine for COVID-19 appears to have a key role to play in patients with rheumatoid arthritis (RA) on disease-modifying anti-rheumatic drugs (DMARDs), on the basis of results from their small study.

The authors write that the kinetics of the vaccine-induced humoral immune response differ between patients with RA who are taking DMARDs and healthy individuals.

In their report in the Lancet Rheumatology, they describe vaccine responses for 51 patients with RA on various DMARD therapies and 20 healthy controls.

Nine participants received two doses of the Moderna vaccine and the remainder received two doses of the Pfizer/BioNTech vaccine.