• COVID-19
• vaccination
• autoimmune diseases

Vaccination against SARS-CoV-2 is crucial for patients with systemic rheumatic diseases (SRDs), who may be at increased risk of severe outcomes post-COVID-19.1 However, as patients with SRDs were not included in the mRNA vaccine trials (ie, Pfizer/BioNTech (BNT162b2) and Moderna (mRNA-1273)), no data exist regarding whether these vaccines might trigger SRD flares. Sparse data suggest that other vaccines may be associated with SRD flares,2 3 possibly from molecular mimicry triggering immune activation or non-specific adjuvant effects. As SRD flares are associated with disease deterioration, increased flares could have serious clinical implications.4

We report the interim results of a web-based survey evaluating SRD flare incidence post-SARS-CoV-2 vaccine. The survey was e-mailed 5 March 2021 to 3545 outpatients with SRDs seen at a large rheumatology division in New York City. ICD-10 algorithms were used to identify SRDs (online supplemental material). A self-reported disease flare was defined as ‘a sudden worsening of your rheumatology condition or arthritis’ within 2 weeks of the vaccine.

As of 12 April 2021, out of 1483 respondents (41.8% response rate), 1101 patients (74.2%) with SRDs reported receiving at least one dose of a SARS-CoV-2 vaccine and provided flare data (mean age: 60.8 years (14.2 years); 80.6% female; 86.0% White and 5.7% Hispanic/Latinx ethnicity). Five hundred and ninety seven patients (54.2%) received Pfizer vaccine, 483 (43.9%) received Moderna vaccine, 16 (1.5%) received Janssen vaccine and 3 (0.3%) received AstraZeneca vaccine. A total of 202 SRD flares were reported by 165 patients (14.9%). History of suspected/confirmed COVID-19 occurred in 7.9% with SRD flare and 6.7% without SRD flare. Mean age of patients reporting an SRD flare was 59.6 years (13.9 years) versus 61.0 years (14.2 years) in the non-flare group; the majority of both groups were female (89.7% vs 80.0%), White (88.5% vs 85.6%) and non-Hispanic/Latinx (95.2% vs 92.2%). 15.9% of patients receiving Moderna vaccine and 14.2% receiving Pfizer vaccine reported SRD flares.

Of the patients receiving either Pfizer or Moderna vaccines, 654 (59.4%) had received both doses. Of these patients, 113 (17.0%) flared, 26 (23.0%) flared only after the first dose, 48 (42.5%) flared only after the second dose and 37 (32.7%) flared after both doses. Flares after the first and second dose of Pfizer vaccine were 10.3% vs 10.9%, and flares after the first and second dose of Moderna vaccine were 9.6% vs 16.3%, respectively.

Both the flare and non-flare groups used medications for prevention and treatment of vaccine side effects (table 1). Most SRD flares were characterised as moderate to severe (57.3% after first vs 62.4% after second dose), and as qualitatively ‘typical’ SRD flares (70.9% after first dose vs 68.2% after second dose). Flares were predominantly reported as joint pain, joint swelling, muscle aches and fatigue (table 1). While 27.7% of flares started 1 day after vaccination, 61.4% began after 2–7 days and 10.9% occurred more than 7 days later (table 1). Most SRD flares resolved within 7 days of onset, but 26.2% lasted for 8–21 days and 8.9% for >21 days.

Interim data from our cohort demonstrate that >85% of patients did not report an SRD flare post-SARS-CoV-2 vaccination. This information is reassuring and can help inform vaccine decision-making for patients with SRDs. Although we did not collect laboratory studies, most SRD flares were described as ‘typical’, suggesting these symptoms are not vaccine’s adverse effects being misreported as disease flares. However, when patients did flare, the majority of flares were reported as moderate to severe, with some lasting >3 weeks. Therefore, it will be important to follow these patients prospectively, as well as to perform analyses which incorporate potential confounders to identify predictors of SRD flares post-vaccination. Whether vaccine manufacturer is an independent predictor of SRD flare remains to be determined.