Background/Purpose: Respiratory syncytial virus (RSV) vaccines were approved starting in May 2023 and are recommended by the US CDC to adults aged 60 years or older at increased risk for poor outcomes, including immunocompromising conditions or medications. We previously showed that RSV is associated with poor outcomes and high rates of hospitalization in people with systemic autoimmune rheumatic diseases (SARDs), but less is known about RSV vaccine uptake among individuals with SARDs. Therefore, we described the prevalence, associations, and breakthrough infection of RSV vaccination among people with SARDs.

Methods: We performed a retrospective, cross-sectional study in a US tertiary healthcare system. We identified patients with 2 or more SARD codes and who were prescribed a DMARD or oral glucocorticoid as of February 2025 (positive predictive value 95%). We excluded patients who had died or whose last encounter was on or before May 2023 and those less than 60 years of age on the last day of observation or at time of RSV vaccination. The primary outcome was RSV vaccination documented in the electronic health record. We evaluated factors associated with RSV vaccination and used multivariable logistic regression to assess for associations. We then described breakthrough infections with positive testing after RSV vaccination.

Results: We analyzed 10,587 SARD patients aged 60 years or older at the time of RSV vaccination or the date of last observation (median age 71.7 years, 72.4% female, and 88.0% White; Table 1). The most common SARD type was RA (56.8%), and the most common medications were conventional synthetic DMARDs (40.8%). We identified 1,075 people with SARDs (10.2%) who received the RSV vaccine. There was no association of any SARD type with RSV vaccination after adjusting for general population factors that included demographics, comorbidities, area-level income, serious infection, and other vaccine receipt (Table 2). Influenza vaccine receipt in the previous year had the strongest association with RSV vaccination (no vs. yes OR 0.021, 95%CI 0.018 to 0.026). No DMARD class was significantly associated with RSV vaccination. CD20 inhibitor use had an OR for RSV vaccination of 0.78 (95%CI 0.45 to 1.36) compared to antimalarial monotherapy. Glucocorticoid users were less likely (OR 0.33, 95%CI 0.23 to 0.49) and interstitial lung disease was more likely (OR 1.53, 95%CI 1.14 to 2.04) to receive RSV vaccination. We identified 9 cases of breakthrough RSV infections, occurring a median of 301 days after vaccination (Table 3).

Conclusion: Among patients with SARDs aged 60 years or older, 10.2% were documented to receive RSV vaccination. After accounting for general population factors, glucocorticoid users were less likely to receive RSV vaccination. Neither SARD type nor DMARD class, including CD20 inhibitors, were associated with RSV vaccination. Only 2 of 9 documented cases of breakthrough RSV infections were hospitalized and there were no deaths. While our study is limited to a single geographic area and may under-capture RSV vaccinations and breakthrough infections, further research on effectiveness and vaccine-induced SARD flares is needed.

Table 1. Characteristics of patients with SARDs at date of RSV vaccine receipt or last observation. Covariates were assessed within a 12-month period prior to date of vaccination or last documented encounter.

Table 2. Odds ratios for documented RSV vaccine receipt among SARD patients (n=10,587).

Table 3. Documented breakthrough infections in SARD patients after RSV vaccination (9 cases out of 1,075 receiving vaccinations).

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/investigating-factors-associated-with-respiratory-syncytial-virus-vaccination-and-breakthrough-infection-among-patients-with-systemic-autoimmune-rheumatic-diseases/