Design: Multicentre, pragmatic randomised trial
Population: 840 adults with inflammatory arthritis on biologic or JAK inhibitor therapy
Primary outcome: Fold-rise in anti-spike IgG at 6 weeks
Effect: Ratio (hold/continue) 0.96 (95% CI 0.36–2.56); flare OR 2.27 (1.41–3.65) with holding

The COVER trial in JAMA Internal Medicine (5 October) randomised 840 people with rheumatoid arthritis, psoriatic arthritis or axial spondyloarthritis to continue, or pause for two weeks, their TNF inhibitor, IL-17 inhibitor, abatacept or JAK inhibitor after a COVID-19 booster.

Antibody responses rose substantially in both groups and did not differ (ratio of fold-rise 0.96). Pausing therapy roughly doubled the odds of a flare (odds ratio 2.27), most clearly with JAK inhibitors; on a validated flare questionnaire, 21% against 9% worsened meaningfully. Flares had resolved in both arms by six weeks.

The question arises constantly on medical wards and in general clinics — before vaccines, and more widely whenever a patient on immunomodulators needs a procedure or a dose of something new. For COVID-19 boosters with these drug classes, the answer is to continue. The trial did not test methotrexate or rituximab, which have their own guidance.

Continue TNF, IL-17, abatacept or JAK inhibitor therapy around a COVID-19 booster
Pausing for two weeks did not improve antibody response
A pause roughly doubled flare risk, most with JAK inhibitors
This trial did not test methotrexate or rituximab — follow drug-specific guidance for those

Why it matters

Holding immunomodulators 'to help the vaccine work' is a common reflex that this trial shows costs flares for no gain.

The statistics, in plain English

The antibody ratio of 0.96 has a very wide 95% CI (0.36 to 2.56), so the trial cannot exclude a modest difference either way — but the flare result, OR 2.27 (1.41 to 3.65), is clearly real, and the risk difference was 12 percentage points.