BackgroundShoulder injury related to vaccine administration (SIRVA) is a rare but increasing complication after vaccination. The aim of this study was to increase awareness of post-vaccination shoulder pain and to investigate the effect of the clinical condition of the shoulder before vaccination on the loss of function that may occur after vaccination.MethodsThis prospective study included 65 patients aged > 18 years who were diagnosed with unilateral shoulder impingement and/or bursitis. The first vaccination was performed on the shoulders with rotator cuff symptoms, then the second vaccination was performed on healthy shoulders of same patients as soon as the health system allowed. Pre-vaccination MRI of the symptomatic shoulders of the patients was performed and VAS, ASES and Constant scores were evaluated. At 2 weeks after vaccination of the symptomatic shoulder, scores were reassessed. For the patients with changes in the scores, MRI was performed again and the treatment of all patients was started. A second vaccination was given to asymptomatic shoulders and the patients were recalled two weeks later and their scores were evaluated.ResultsAfter vaccination, the symptomatic shoulder of 14 patients was affected. No clinical changes were observed in the asymptomatic shoulders after vaccination. The VAS scores of the symptomatic shoulders evaluated after vaccination were significantly higher than the scores evaluated before vaccination (p= 0.001). The ASES and Constant scores of symptomatic shoulders evaluated after vaccination were significantly decreased compared to the scores evaluated before vaccination (p= 0.001).ConclusionsExacerbation of symptoms may occur if symptomatic shoulders are vaccinated. Before vaccination, a detailed anamnesis should be taken from the patients and vaccination should be performed to the asymptomatic side.