• COVID-19
• vaccination
• epidemiology

Patients with inflammatory rheumatic and musculoskeletal diseases (iRMDs) are often treated with immunomodulatory or immunosuppressive medications; consequently, they have been excluded alongside other immunocompromised patients from late stages of SARS-CoV-2 vaccine trials. SARS-CoV-2 vaccine efficacy in this population is unclear, though initial data are reassuring overall.

However, a slightly lower SARS-CoV-2 immunogenicity of vaccines has been documented in some patients with iRMD.1 2 Some common rheumatic and musculoskeletal disease (RMD) medications have been highlighted as possible influential factors on immunogenicity, particularly rituximab (RTX), mycophenolate mofetil (MMF), methotrexate (MTX), abatacept and glucocorticoids.3–7

The European Alliance of Associations for Rheumatology (EULAR) launched a COVID-19 registry in March 2020, capturing COVID-19 outcomes in the European RMD population. Questions on reinfection and vaccination were added in January 2021. A further EULAR registry (COVAX) was launched in February 2021 to collect data on COVID-19 vaccination and related adverse events among patients with RMD. Here we describe a series of patients who contracted SARS-CoV-2 infection after COVID-19 vaccination between 19 January 2021 and 27 July 2021.

The series consists of 38 adults with iRMDs, 8 from the COVID-19 registry (<1%, out of 9118 patients with iRMD diagnosed with COVID-19) and 30 from the COVAX registry (<1%, out of 4393). Cases were deemed eligible if they were ‘partially vaccinated’ (≥14 days after dose 1 to <14 days after dose 2) or ‘fully vaccinated’ (≥14 days after dose 2/single dose), as per Centers for Disease Control and Prevention definitions8 (17 cases were excluded for this reason). A quarter (26%) were fully vaccinated and 28 cases (74%) were partially vaccinated.

As shown in table 1, 76% of the series is female, with a median age of 58 (IQR 49–65) from 12 countries. The most frequent iRMD diagnoses were rheumatoid arthritis (RA, 45%), axial spondyloarthritis (axSpA, 24%), systemic sclerosis (SSc, 8%) and systemic lupus erythematosus (8%). Most were in remission (47%) or had low disease activity (34%). The top iRMD medications were glucocorticoids (32%), MTX (26%) and tumour necrosis factor inhibitors (TNFi, 26%). The median glucocorticoid dose in users was 5 mg/day (IQR 5–10).

The most common comorbidities among COVID-19 registry cases were hypertension (38%) and cardiovascular disease (25%). Comorbidities are not reported in the COVAX registry. Out of the 30 COVAX cases, 29 had no SARS-CoV-2 infection prior to vaccination, and this was unknown in one case. These data are not collected in the COVID-19 registry.

Seventy-nine per cent received the Pfizer/BioNTech vaccine; 11% received AstraZeneca; 8% received CoronaVac/Sinovac; and 3% received Moderna. Sixty-one per cent had one vaccine dose before COVID-19; 34% had two; and 5% had three. Median times from vaccination to infection are shown in table 1.

Most patients (74%) fully recovered from the SARS-CoV-2 infection; however, several patients recovered with ongoing sequelae (8%) and three patients died (8%).

Two of the deceased patients were male: one >80-year-old man with SSc, treated with glucocorticoids (10 mg/day) and MMF, who received one Pfizer vaccine 18 days prior to SARS-CoV-2 infection (therefore this patient was not fully vaccinated); one >70-year-old man with RA, treated with glucocorticoids (5 mg/day) who received two Pfizer doses (44 and 22 days before SARS-CoV-2 infection). The other patient was female: a >70-year-old woman with RA and Sjogren’s syndrome, treated with RTX (the most recent RTX infusion was 195 days before the first vaccine), who received two Pfizer vaccines (60 and 32 days prior to infection) (table 2).

The three patients who recovered with ongoing sequelae had axSpA and RA, and were treated with abatacept, interleukin-6 inhibitors, sulfasalazine and TNFi (table 2).

Overall, the low numbers of SARS-CoV-2 infection postvaccination in both registries are encouraging. Some observations described here have already been highlighted in existing research; for example, all three deceased patients were treated with medications that are potential negative influences on postvaccination SARS-CoV-2 immunogenicity in the RMD population.3 7 However, no vaccine has perfect efficacy; thus, a small number of postvaccination diagnoses of SARS-CoV-2 infections were expected, similarly to existing clinical trial observations; the influence of RMD medications on immunity after vaccination is still unclear.

There are significant limitations to this case series. The sample size is not sufficiently powered to evaluate associations between iRMD population-specific factors and SARS-CoV-2 infection after COVID-19 vaccination or to calculate a vaccine failure rate. Both the EULAR COVID-19 and COVAX registries rely on voluntary case submission, leading to selection bias in the data. No information is provided concerning the presence or the titre of postvaccine antibodies at the time of the infection. No causal conclusions can be drawn from this dataset, and the observations highlighted here cannot be extrapolated onto the wider iRMD population. Further research is needed to more deeply examine possible links between iRMD and medication-specific factors and SARS-CoV-2 infection after vaccination.