Shoulder injury a rare potential side effect of vaccination

Researchers from Kaiser Permanente Southern California Department of Research & Evaluation studied health records for more than 3.7 million administered vaccinations during the study period to estimate the risk for shoulder conditions after vaccination and assess possible risk factors. A natural-language processing (NLP) algorithm was used to identify potential shoulder conditions among vaccinated persons with shoulder disorder diagnosis codes and the characteristics of vaccinated persons with and without shoulder conditions were compared. Among more than 3.7 million administered vaccinations, 371 cases of shoulder condition were identified, with an estimated incidence of 0.99 per 10,000 adult vaccinations. The incidence was even less for pediatric recipients, with only 4 cases of shoulder conditions in more than 750,000 vaccinations.

The researchers also looked at risk factors for developing shoulder conditions and found that among adults, advanced age, female sex, an increased number of outpatient visits in the 6 months before vaccination, having fewer comorbidities, and receiving pneumococcal conjugate vaccine were associated with a higher risk for shoulder conditions. Among influenza vaccines, quadrivalent vaccines were associated with an increased risk for shoulder conditions. Simultaneous administration of vaccines was associated with a higher risk for shoulder conditions among elderly persons.