Shoulder Injury Related to Vaccine Administration (SIRVA); Cutibacterium acnes (C. acnes) culure positive; Pain immediately following vaccination/Increasing pain; Limitations with overhead activities and external rotation; Weakness with rock-climbing activities and heavy lifting; Tendinopathy; Bony erosions of 3-4 mm; Increased bone marrow edema on the posterior lateral proximal humerus; This literature case was received on 02-Oct-2023 and concerned a 36-year-old, female patient.  The purpose of this manuscript is to raise awareness of potential coexistence of SIRVA and Cutibacterium acnes which may be of assistance to surgeons treating refractory cases of SIRVA. The aim of this study is to provide a provisional framework for the workup and treatment of patients with Shoulder Injury Related to Vaccine Administration (SIRVA) and to raise the possibility of infection as a concomitant condition in the presence of refractory SIRVA.  Clinical case files were reviewed for 3 cases of SIRVA with positive cultures for C. acnes were reviewed. Presentation, treatment, and clinical outcomes were compared.  The patient's medical history and concomitant medications were not reported.  On an unspecified date, the patient was vaccinated with influenza vaccine (brand not specified; anatomical location: left deltoid (reported as 'high on the posterior deltoid'); dose, route of administration and indication: not reported). The batch number was not reported.  On the same date, immediately after receiving the influenza vaccine, the patient experienced pain. Pain was rated 4/10 at rest and 7/10 visual analog scale (VAS) upon exertion. Single assessment numeric evaluation (SANE) score at initial presentation was 10/100. The patient experienced full range of shoulder motion but had severe limitations with overhead activities and external rotation such as buckling a seat belt or retrieving bags from the back seat of a vehicle. The patient ceased rock climbing and overhead activities requiring strength.  On an unspecified date, because of failure to improve, the patient sought medical care; the patient first obtained a magnetic resonance imaging (MRI) four weeks after vaccination which revealed increased signal in the subacromial bursa, fluid tracking along the teres minor insertion and a superior labrum anterior to posterior lesion. Conservative management was initiated with oral anti-inflammatories and physical therapy. That resulted in a decrease in symptoms at 4-8 weeks.  On an unspecified date, the patient developed increasing pain and disability by 12-16 weeks. Conservative management with oral anti-inflammatories, physical therapy, and 2 corticosteroid injections provided limited relief.   On an unspecified date, approximately 16 weeks after presentation, diagnostic ultrasound was performed due to ongoing pain, which revealed teres minor tendinopathy and bony erosions. Subsequently, repeat MRI was performed which showed increased bone marrow oedema on the posterior lateral proximal humerus which correlated with the patient's area of vaccine administration.  On an unspecified date, after failure of conservative measures for 6 months, the patient elected to proceed with diagnostic arthroscopy with intraoperative cultures. One of 3 cultures returned positive for Cutibacterium acnes (C. acnes), 12 days after biopsy. The positive biopsy was from the bone sample. Concomitantly with diagnostic arthroscopy, the patient underwent extensive debridement of the subacromial space and greater tuberosity with an arthroscopic shaver and suction lavage. A total of 6 liters of saline was used during this portion of the procedure.  On an unspecified date, the patient was placed on intravenous antibiotic therapy with Rocephin (ceftriaxone sodium), but 8 days after starting the therapy, the patient had an adverse reaction, and then was switched to Invanz (ertapenem). The patient experienced rapid relief of symptoms within days and progressed to near full recovery 2-3 months after arthroscopy.  On an unspecified date, the patient reported some limitations secondary to pain and weakness with rock-climbing activities and heavy lifting overhead with a SANE score of 95/100.  The outcome of the events of 'shoulder injury related to vaccine administration', 'Cutibacterium acnes infection', 'pain', 'mobility decreased', 'weakness of upper extremities', 'tendinopathy', 'bone loss' and ' bone marrow edema' was not reported.  The reporter did not provide a causality assessment.  All events were considered to be medically significant by Physician.  In all cases, patients were thin (body mass index < 23), females, who had high injection placement of a vaccine, all patients had positive magnetic resonance imaging indings of increased signal in the subacromial bursa, and/or greater tuberosity. All patients underwent arthroscopic debridement and culture harvest and cultures were positive for C. acnes. A combination of oral and intravenous antibiotics was used, and all patients demonstrated clinical improvement from the preoperative state.  Based on available case reports and limited data, surgeons may consider the possibility of C. acnes positivity in the workup and treatment of persistent shoulder pain after vaccine administration. A history of small body habitus, high injection site location, pain at rest or with sleep, and loss of shoulder motion and strength should raise an index of suspicion for advanced imaging and, in select cases, arthroscopy with harvest of tissue cultures and concomitant arthroscopic debridement.   This case is linked with case 202304465 (the same literature article).  Company comment: A 36-year-old, female patient was vaccinated with the suspect product influenza vaccine. On the same date following vaccination the patient experienced pain. The patient had severe limitations with overhead activities and external rotation such as buckling. Approximately 16 weeks after presentation, diagnostic ultrasound was performed due to ongoing pain, which revealed teres minor tendinopathy and bony erosions. Subsequently, repeat MRI was performed which showed increased bone marrow oedema on the posterior lateral proximal humerus which correlated with the patient's area of vaccine administration. Cultures taken during surgical procedures were positive for C. acnes. Information regarding the underlying medical history and concomitant medications has not been provided. Although influenza vaccine administration may have not led to the development of bacterial infections, the vaccine administration itself may have put the patient under risk. Causality for the event Cutibacterium acnes infection is therefore assessed as possibly related. Causality for the remaining events shoulder injury related to vaccine administration, bone loss, bone marrow oedema, pain, mobility decreased, tendon disorder and muscular weakness is assessed as possibly related based on plausible temporal relationship.; Sender's Comments: A 36-year-old, female patient was vaccinated with the suspect product influenza vaccine. On the same date following vaccination the patient experienced pain. The patient had severe limitations with overhead activities and external rotation such as buckling. Approximately 16 weeks after presentation, diagnostic ultrasound was performed due to ongoing pain, which revealed teres minor tendinopathy and bony erosions. Subsequently, repeat MRI was performed which showed increased bone marrow oedema on the posterior lateral proximal humerus which correlated with the patient's area of vaccine administration. Cultures taken during surgical procedures were positive for C. acnes. Information regarding the underlying medical history and concomitant medications has not been provided. Although influenza vaccine administration may have not led to the development of bacterial infections, the vaccine administration itself may have put the patient under risk. Causality for the event Cutibacterium acnes infection is therefore assessed as possibly related. Causality for the remaining events shoulder injury related to vaccine administration, bone loss, bone marrow oedema, pain, mobility decreased, tendon disorder and muscular weakness is assessed as possibly related based on plausible temporal relationship.