shoulder injury related to vaccine administration; limited shoulder ROM; Frozen shoulder/Adhesive capsulitis; right-dominant shoulder pain/pain as localized deep in the shoulder anteriorly/shoulder pain was exacerbated with activity, especially lifting, sleeping, and reaching behind her back; mild subacromial bursitis; Discomfort; greater disruption in her activities of daily living necessitating her initial visit; This case was reported in a literature article and described the occurrence of shoulder injury related to vaccine administration in a 46-year-old female patient who received Flu Seasonal QIV Dresden (Influenza vaccine Quadrivalent unspecified season) for prophylaxis.   Previously administered products included Influenza shot with an associated reaction of no adverse event (no past issues with vaccination).   On an unknown date, the patient received Influenza vaccine Quadrivalent unspecified season. On an unknown date, less than a day after receiving Influenza vaccine Quadrivalent unspecified season, the patient experienced shoulder injury related to vaccine administration (serious criteria hospitalization), injected limb mobility decreased (serious criteria hospitalization), frozen shoulder (serious criteria hospitalization), shoulder pain (serious criteria hospitalization), subacromial bursitis (serious criteria hospitalization), discomfort (serious criteria hospitalization) and activities of daily living impaired (serious criteria hospitalization). The patient was treated with steroids nos (Steroid Injection) and anesthetic, nos (Anesthesia). On an unknown date, the outcome of the shoulder injury related to vaccine administration, injected limb mobility decreased, frozen shoulder, shoulder pain, subacromial bursitis, discomfort and activities of daily living impaired were recovered/resolved.   The reporter considered the shoulder injury related to vaccine administration, injected limb mobility decreased, frozen shoulder, shoulder pain, subacromial bursitis, discomfort and activities of daily living impaired to be related to Influenza vaccine Quadrivalent unspecified season.  Additional details were reported as follows: This case was reported in a literature article and described the occurrence of frozen shoulder injury related to vaccine administration (SIRVA) in a 46-years old female patient, who was vaccinated with unspecified influenza vaccine (manufacturer unknown) for prophylaxis. The patient was previously healthy with 86 kg body weight and 32.5 body mass index. The patient previously had yearly influenza shots and recalled no past issues with vaccinations. The patient had no history of shoulder pain, trauma, inflammation, or dysfunction. The patient's medical and orthopedic histories were otherwise unremarkable. The patient was on no medications and had no known allergies. The patient worked from home in an office capacity using the computer daily. No information on patient's family history, concurrent condition or concomitant medication was provided. On an unspecified date, the patient received yearly routine unspecified influenza vaccine (administration route and site unspecified, dosage unknown; batch number not provided) by the nursing staff at primary care office. The age of vaccination was not provided. On an unspecified date, within hours after the administration of influenza vaccine, the patient's right-dominant shoulder pain started. [Her right-dominant shoulder pain started within hours after administration of her yearly routine influenza vaccine injection by the nursing staff at her primary care office]. The patient presented to sports medicine clinic with the complaint of 4 months duration right shoulder pain. The patient described her pain as localized deep in the shoulder anteriorly. The patient had never been pain-free since the vaccination injection. The pain and range of motion (ROM) limitations slowly progressed over the 4 months before her presentation with increasing shoulder pain, limited shoulder ROM and functional ability, and greater disruption in her activities of daily living necessitating her initial visit. The patient's shoulder pain was exacerbated with activity, especially lifting, sleeping, and reaching behind her back. On initial examination, the patient had very limited right shoulder ROM and experienced pain with both active and passive ROM. Shoulder deficits on examination demonstrated active flexion to 100 degree, passive forward flexion to 100 degree, internal rotation to the level of the sacrum, and passive external rotation to 30 degree. Pain was elicited with shoulder flexion and extension, but no pain noted with cross-chest adduction or acromioclavicular joint palpation. No motor weakness or scapular winging was noted. No erythema, warmth, or muscle atrophy on inspection. Right shoulder was neurovascular intact, and comparison left shoulder examination was all within normal limits. Anteroposterior radiographs of the right shoulder demonstrated no glenohumeral arthritis and normal joint alignment. Coronal T2-weighted magnetic resonance imaging demonstrated normal deltoid musculature and mild subacromial bursitis with significant inflammation and thickening of the joint capsule and obliteration of the axillary recess, consistent with adhesive capsulitis. The patient was given a glenohumeral joint steroid injection under fluoroscopy with subsequent physical therapy for shoulder ROM to discomfort but not to pain. The patient failed conservative management, and 7 months post-vaccination, the patient underwent shoulder manipulation under anesthesia with excellent results. Scar tissue release was palpated, and full ROM equal to the opposite side was achieved under anesthesia after manipulation. The patient subsequently madpe improvements with her shoulder ROM and her functional reach, and at 9 months post-vaccination (2 months post-manipulation), the patient felt that her ROM and strength allowed her to conduct her desired daily activities. The patient was discharged with a home-exercise physical therapy maintenance program. Her final diagnosis was suspected frozen shoulder injury related to vaccine administration (SIRVA). This case has been considered as serious due to hospitalization. The authors commented, Very few adverse effects have been reported from influenza vaccinations. The development of symptoms after vaccination, with the absence of evidence of infection or trauma, is consistent with previously described cases of SIRVA. The patient had no history of shoulder dysfunction, and the onset of pain with limitation of shoulder ROM developed almost immediately after vaccine administration. The proposed mechanism of injury is attributed to a robust local immune-mediated inflammatory response related to vaccine material injected directly into the subdeltoid/subacromial bursa and/or synovial tissue. The presentation of adhesive capsulitis (as demonstrated by the patient's pain, decreased ROM, weakness, and impaired mobility/functionality) with collaborative physical and radiographic findings are all much more than would be expected by the routine trauma of vaccination and are consistent with SIRVA. The CDC recommended length of the injection needle may be longer than needed and may put some patients (especially women) at risk of needle over-penetration and SIRVA. Individualizing needle length selection for muscle penetration and use of a standardized injection technique with proper injection positioning should be used. Needle penetration should be into the deltoid at 90 degrees, with the patient's arm placed in 60 degrees of lateral abduction, hand on hip, and injected midway between the acromion and the deltoid tuberosity. Shoulder injury related to vaccine administration has been reported with both pneumococcal and influenza vaccinations. This case report should serve as a catalyst for discussion regarding vaccination technique, location, and potential needle over-penetration. The subdeltoid/subacromial bursa is prone to accidental infiltration in high-deltoid intramuscular vaccinations, causing a severe local immune inflammatory response. This complication can be prevented if the vaccination is administered at the correct site using the correct needle size. A greater understanding of the anatomy and use of the correct intramuscular administration technique is important to prevent this rare post-vaccination complication. Practitioners should consider SIRVA as part of the differential diagnosis in patients presenting with acute shoulder pain after vaccine administration.