Key takeaways:

• More than 80% of patients with inflammatory idiopathic myopathy seroconverted after vaccination.
• Mostly mild adverse events were reported.

More than 80% of immunosuppressed patients with idiopathic inflammatory myopathy achieved seroconversion after receiving the recombinant zoster vaccine, according to data published in Arthritis Care & Research.

“Although [the recombinant zoster vaccine (RZV)] has shown an overall favorable safety profile in patients with [autoimmune rheumatic diseases (ARDs)], concerns persist regarding vaccination in [idiopathic inflammatory myopathies (IIM)], particularly considering sporadic reports of disease onset or flares following various vaccines, including those against influenza and SARS-CoV-2,” Sandra G. Pasoto MD, PhD, of Hospital das Clínicas HCFMUSP and the University of São Paulo, in Brazil, and colleagues wrote.

Data derived from Pasoto SG, et al. Arthritis Care Res. 2026;doi:10.1002/acr.80103.

“Although causality has not been established, these observations highlight the need for disease-specific safety data to guide evidence-based counseling and vaccination recommendations in clinical practice,” they added.

To examine the immunogenicity and safety of RZV (Shingrix, GlaxoSmithKline) in immunosuppressed patients with idiopathic inflammatory myopathies, Pasoto and colleagues conducted a subanalysis of a previous prospective, randomized, placebo-controlled phase 4 study performed at their tertiary center. That study included patients with ARDs who were immunosuppressed and 280 health control participants.

The 70 patients with idiopathic inflammatory myopathy included in the study were identified via 2017 American College of Rheumatology/EULAR criteria. These patients, along with the healthy controls, received two RZV doses. The researchers defined seroconversion as a fourfold or greater increase in anti-gE antibodies. Geometric mean titers and factor increase geometric mean titers also underwent analysis.

Baseline data showed that patients in the idiopathy inflammatory myopathy group were on average younger than the control group (53 years vs. 55 years; P = .005). A higher prevalence of previous herpes zoster also was reported in the patient population compared with controls (36.7% vs. 13.3%; P < .001).

According to the researchers, seroconversion occurred in 83.3% of participants in the idiopathic inflammatory myopathy group, and in 99.3% of controls (P < .001). Additionally, both post-vaccination geometric mean titers (6.4 vs. 11.8 mIU/mL; P = .001) and factor increase geometric mean titers (21.8 vs. 53; P = .001) were lower in the idiopathic inflammatory myopathy group compared with controls.

Multivariable regression analysis findings showed several factors associated with reduced likelihood of seroconversion, including mycophenolate mofetil use, higher baseline cutaneous activity and higher baseline geometric mean titers (P < .05), according to the researchers.

Half of the patients with idiopathic inflammatory myopathy and 72.8% of controls experienced adverse events (P < .001). The researchers noted that these events were “mostly mild.”

Activity scores were comparable across the two groups (P < .05).

“This phase 4 study shows that RZV was safe and induced seroconversion in most patients with IIM, without evidence of vaccine-related disease activation, supporting the use of RZV in this immunosuppressed population,” Pasoto and colleagues wrote. “Although lower post-vaccination antibody levels raise uncertainty regarding long-term protection, reduced vaccine responsiveness associated with MMF exposure and active cutaneous disease suggests that tailored vaccination strategies may benefit selected patients.”