What Do We Know About Shoulder Injury Related to Vaccine Administration? An Updated Systematic Review.

BACKGROUND: Shoulder injury related to vaccine administration (SIRVA) is postulated to be an immune-mediated inflammatory response to a vaccine antigen injected into or near the subacromial bursae or synovium, leading to shoulder pain and dysfunction. The number of studies on this topic is rapidly increasing. Recent comparative studies have reported conflicting conclusions, which suggests that a systematic review of the best-available evidence may be helpful. QUESTIONS/PURPOSES: In this systematic review, we asked: What are the (1) clinical characteristics, (2) diagnoses, and (3) management approaches and outcomes reported in association with SIRVA? METHODS: A search was performed on October 4, 2021, of the PubMed and Medline databases for studies related to SIRVA. Inclusion criteria were English-language comparative studies, case series, and case reports that involved shoulder pain occurring after vaccination. Studies of exclusively neurologic conditions after vaccination were excluded. Forty-two studies met the eligibility criteria, including three retrospective comparative studies (72 patients and 105 controls), five database case series (2273 patients), and 34 case reports (49 patients). Study quality was assessed for the database case series and retrospective comparative studies using the Methodological Index for Non-randomized Studies tool. RESULTS: Among patients in the case reports, the median age was 51 years (range 15-90 years), and 73% (36 of 49) were women. BMI was reported for 24% of patients (12 of 49) in case reports, with a median of 23.5 kg/m2 (range 21-37.2 kg/m2). The most common symptoms were shoulder pain and reduced ROM. The most common diagnoses were shoulder bursitis, adhesive capsulitis, and rotator cuff tears. The most frequent management modalities included physical or occupational therapy, NSAIDs, and steroid injections, followed by surgery, which was generally used for patients whose symptoms persisted despite nonsurgical management. Full resolution of symptoms was reported in 2.9% to 56% of patients. CONCLUSION: The association between inflammatory conditions of the shoulder (such as bursitis) and vaccination appears to be exceedingly rare, occurring after approximately 1:130,000 vaccination events according to the best-available comparative study. Currently, there is no confirmatory experimental evidence supporting the theory of an immune-mediated inflammatory response to vaccine antigens. Although the clinical evidence is limited, similar to any bursitis, typical treatments appear effective, and surgery should rarely be performed. Additional research is needed to determine the best injection technique or evaluate alternate injection sites such as the anterolateral thigh that do not involve positioning a needle close to the shoulder.