Research Summary

SIRVA Rare but More Frequent After COVID-19 vs Influenza Vaccination

Edited by:
Brian McCurdy

Key Highlights

  • SIRVA incidence was 1.84 per 10,000 COVID-19 vaccinations versus 1.15 per 10,000 influenza vaccinations.
  • The adjusted relative risk was 1.63, with an absolute increase of 0.67 cases per 10,000 vaccinations.
  • Among adults ≥65, risk did not differ significantly between COVID-19 and high-dose influenza vaccination.

Shoulder injury related to vaccine administration (SIRVA) was rare after both COVID-19 and influenza vaccination. Still, it occurred more frequently after COVID-19 vaccination in a population-based cohort study published in JAMA Internal Medicine. The adjusted difference corresponded to approximately 7 additional cases per 100,000 vaccinations.

Researchers evaluated adults aged ≥18 who received an intramuscular deltoid injection of either vaccine between August 1, 2023, and April 30, 2024. The primary outcome was incident SIRVA, defined as shoulder symptoms beginning within 7 days after vaccination and persisting for more than 30 days. Cases were identified using a validated natural language processing algorithm. Investigators calculated incidence per 10,000 vaccinations and estimated adjusted relative risks and risk differences using robust Poisson regression with inverse probability of treatment weighting.

Study Findings

The overall cohort included 1,366,362 adults receiving 1,901,588 vaccinations. Mean age was 58.4 years, and 57.3% were female. In the primary analysis of 1,830,636 vaccinations, investigators identified 110 SIRVA cases after 596,614 COVID-19 vaccinations and 142 after 1,234,022 influenza vaccinations. Incidence was 1.84 (95% CI, 1.53–2.22) versus 1.15 (95% CI, 0.98–1.36) per 10,000 vaccinations, respectively. The adjusted relative risk was 1.63 (95% CI, 1.16–2.28), with an adjusted absolute increase of 0.67 cases (95% CI, 0.15–1.19) per 10,000 vaccinations.

Among adults aged ≥65, incidence was 2.11 per 10,000 COVID-19 vaccinations and 1.63 per 10,000 high-dose influenza vaccinations. This comparison was not statistically significant (adjusted relative risk, 1.41; 95% CI, 0.92–2.15). Another 13 cases occurred among 70,952 simultaneous COVID-19 and influenza vaccinations. Nearly all COVID-19 vaccines were Pfizer-BioNTech mRNA vaccines, while influenza vaccines were predominantly standard-dose or high-dose inactivated quadrivalent formulations.

Clinical Implications

According to the authors, vaccine-associated inflammatory responses, alongside injection technique, may contribute to SIRVA risk. They emphasized that the absolute risk was small and should be considered alongside the established benefits of vaccination in preventing severe disease and hospitalization.

Expert Commentary

“Among adults aged 65 years or older, SIRVA risk did not differ significantly between COVID-19 and high-dose influenza vaccination,” the researchers concluded.

Reference

Zheng C, Qian L, Sy LS, et al. Risk of shoulder injury related to vaccine administration for COVID-19 and influenza vaccinations. JAMA Intern Med. Published online November 4, 2026. doi:10.1001/jamainternmed.2026.5899