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The U.S. COVID-19 vaccination program, which commenced in December 2020, has been instrumental in preventing morbidity and mortality from COVID-19 disease. Safety monitoring has been an essential component of the program. The federal government undertook a comprehensive and coordinated approach to implement complementary safety monitoring systems and to communicate findings in a timely and transparent way to healthcare providers, policymakers, and the public. Monitoring involved both well-established and newly developed systems that relied on both spontaneous (passive) and active surveillance methods. Clinical consultation for individual cases of adverse events following vaccination was performed, and monitoring of special populations, such as pregnant persons, was conducted. This report describes the U.S. government's COVID-19 vaccine safety monitoring systems and programs used by the Centers for Disease Control and Prevention, the U.S. Food and Drug Administration, the Department of Defense, the Department of Veterans Affairs, and the Indian Health Service. Using the adverse event of myocarditis following mRNA COVID-19 vaccination as a model, we demonstrate how the multiple, complementary monitoring systems worked to rapidly detect, assess, and verify a vaccine safety signal. In addition, longer-term follow-up was conducted to evaluate the recovery status of myocarditis cases following vaccination. Finally, the process for timely and transparent communication and dissemination of COVID-19 vaccine safety data is described, highlighting the responsiveness and robustness of the U.S. vaccine safety monitoring infrastructure during the national COVID-19 vaccination program., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Katherine Edwards serves as an advisor to Bionet, Dynavax, and IBM, and is on DSMBs Sanofi, X-4 Pharma, Seqirus, Moderna, Pfizer, Merck, Roche, Novavax, and Brighton Collaboration. KM Edwards also reports grants from CDC and NIH. C. Buddy Creech serves as a consults for Pfizer, GSK, Moderna, CommenseBio, and TDCowen. CB Creedch also serves on a DSMB for GSK. Nicola P. Klein reports research support from Pfizer for COVID-19 vaccine clinical trials and from Sanofi Pastuer, Merck, GSK, and Sequirus. unrelated to the work in this manuscript. Matthew Oster serves as the Emory Principal Investigator for a Pfizer-funded NIH study. All other authors have declared that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Ltd.)

During the COVID-19 pandemic, candidate COVID-19 vaccines were being developed for potential use in the United States on an unprecedented, accelerated schedule. It was anticipated that once available, under U.S. Food and Drug Administration (FDA) Emergency Use Authorization (EUA) or FDA approval, COVID-19 vaccines would be broadly used and potentially administered to millions of individuals in a short period of time. Intensive monitoring in the post-EUA/licensure period would be necessary for timely detection and assessment of potential safety concerns. To address this, the Centers for Disease Control and Prevention (CDC) convened an Advisory Committee on Immunization Practices (ACIP) work group focused solely on COVID-19 vaccine safety, consisting of independent vaccine safety experts and representatives from federal agencies - the ACIP COVID-19 Vaccine Safety Technical Work Group (VaST). This report provides an overview of the organization and activities of VaST, summarizes data reviewed as part of the comprehensive effort to monitor vaccine safety during the COVID-19 pandemic, and highlights selected actions taken by CDC, ACIP, and FDA in response to accumulating post-authorization safety data. VaST convened regular meetings over the course of 29 months, from November 2020 through April 2023; through March 2023 FDA issued EUAs for six COVID-19 vaccines from four different manufacturers and subsequently licensed two of these COVID-19 vaccines. The independent vaccine safety experts collaborated with federal agencies to ensure timely assessment of vaccine safety data during this time. VaST worked closely with the ACIP COVID-19 Vaccines Work Group; that work group used safety data and VaST's assessments for benefit-risk assessments and guidance for COVID-19 vaccination policy. Safety topics reviewed by VaST included those identified in safety monitoring systems and other topics of scientific or public interest. VaST provided guidance to CDC's COVID-19 vaccine safety monitoring efforts, provided a forum for review of data from several U.S. government vaccine safety systems, and assured that a diverse group of scientists and clinicians, external to the federal government, promptly reviewed vaccine safety data. In the event of a future pandemic or other biological public health emergency, the VaST model could be used to strengthen vaccine safety monitoring, enhance public confidence, and increase transparency through incorporation of independent, non-government safety experts into the monitoring process, and through strong collaboration among federal and other partners., Competing Interests: Declaration of competing interest Kathryn M. Edwards reports relationships that include: membership on Data Safety and Monitoring Boards for COVID-19 vaccine studies for Pfizer and for respiratory vaccines for Moderna, Sequirus, Sanofi, and GlaxoSmithKline. She serves on adjudication committees for Pfizer and X-4 Pharma., (Published by Elsevier Ltd.)

Background: On 2/27/2021, FDA authorized Janssen COVID-19 Vaccine (Ad.26.COV2.S) for use in individuals 18 years of age and older. Vaccine safety was monitored using the Vaccine Adverse Event Reporting System (VAERS), a national passive surveillance system, and v-safe, a smartphone-based surveillance system., Methods: VAERS and v-safe data from 2/27/2021 to 2/28/2022 were analyzed. Descriptive analyses included sex, age, race/ethnicity, seriousness, AEs of special interest (AESIs), and cause of death. For prespecified AESIs, reporting rates were calculated using the total number of doses of Ad26.COV2.S administered. For myopericarditis, observed-to-expected (O/E) analysis was performed based on the number verified cases, vaccine administration data, and published background rates. Proportions of v-safe participants reporting local and systemic reactions, as well as health impacts, were calculated., Results: During the analytic period, 17,018,042 doses of Ad26.COV2.S were administered in the United States, and VAERS received 67,995 reports of AEs after Ad26.COV2.S vaccination. Most AEs (59,750; 87.9 %) were non-serious and were similar to those observed during clinical trials. Serious AEs included COVID-19 disease, coagulopathy (including thrombosis with thrombocytopenia syndrome; TTS), myocardial infarction, Bell's Palsy, and Guillain-Barré syndrome (GBS). Among AESIs, reporting rates per million doses of Ad26.COV2.S administered ranged from 0.06 for multisystem inflammatory syndrome in children to 263.43 for COVID-19 disease. O/E analysis revealed elevated reporting rate ratios (RRs) for myopericarditis; among adults ages 18-64 years, the RR was 3.19 (95 % CI 2.00, 4.83) within 7 days and 1.79 (95 % CI 1.26, 2.46) within 21 days of vaccination. Of 416,384 Ad26.COV2.S recipients enrolled into v-safe, 60.9 % reported local symptoms (e.g. injection site pain) and 75.9 % reported systemic symptoms (e.g., fatigue, headache). One-third of participants (141,334; 33.9 %) reported a health impact, but only 1.4 % sought medical care., Conclusion: Our review confirmed previously established safety risks for TTS and GBS and identified a potential safety concern for myocarditis., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Ltd.)

Background: The mechanism for anaphylaxis following mRNA COVID-19 vaccination has been widely debated; understanding this serious adverse event is important for future vaccines of similar design. A mechanism proposed is type I hypersensitivity (i.e., IgE-mediated mast cell degranulation) to polyethylene glycol (PEG). Using an assay that, uniquely, had been previously assessed in patients with anaphylaxis to PEG, our objective was to compare anti-PEG IgE in serum from mRNA COVID-19 vaccine anaphylaxis case-patients and persons vaccinated without allergic reactions. Secondarily, we compared anti-PEG IgG and IgM to assess alternative mechanisms., Methods: Selected anaphylaxis case-patients reported to U.S. Vaccine Adverse Event Reporting System December 14, 2020-March 25, 2021 were invited to provide a serum sample. mRNA COVID-19 vaccine study participants with residual serum and no allergic reaction post-vaccination ("controls") were frequency matched to cases 3:1 on vaccine and dose number, sex and 10-year age category. Anti-PEG IgE was measured using a dual cytometric bead assay (DCBA). Anti-PEG IgG and IgM were measured using two different assays: DCBA and a PEGylated-polystyrene bead assay. Laboratorians were blinded to case/control status., Results: All 20 case-patients were women; 17 had anaphylaxis after dose 1, 3 after dose 2. Thirteen (65 %) were hospitalized and 7 (35 %) were intubated. Time from vaccination to serum collection was longer for case-patients vs controls (post-dose 1: median 105 vs 21 days). Among Moderna recipients, anti-PEG IgE was detected in 1 of 10 (10 %) case-patients vs 8 of 30 (27 %) controls (p = 0.40); among Pfizer-BioNTech recipients, it was detected in 0 of 10 case-patients (0 %) vs 1 of 30 (3 %) controls (p >n 0.99). Anti-PEG IgE quantitative signals followed this same pattern. Neither anti-PEG IgG nor IgM was associated with case status with both assay formats., Conclusion: Our results support that anti-PEG IgE is not a predominant mechanism for anaphylaxis post-mRNA COVID-19 vaccination., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Mary A Staat reports a relationship with Pfizer that includes: funding grants. Mary A Staat reports a relationship with Merck & Co Inc that includes: funding grants. Mary A Staat reports a relationship with UpToDate that includes: consulting or advisory. Donna S. Hummell reports a relationship with Merck & Co Inc that includes: consulting or advisory. Kathryn M. Edwards reports a relationship with Bionet that includes: consulting or advisory. Kathryn M. Edwards reports a relationship with IBM that includes: consulting or advisory. Kathryn M. Edwards reports a relationship with Member Data that includes: consulting or advisory. Kathryn M. Edwards reports a relationship with Sanofi, X-4 Pharma, Seqirus, Moderna, Pfizer, Merck, Roache, Novavax, Brighton Collaboration that includes: consulting or advisory. UpToDate fees for Mary A. Stadt were classified as royalties that are unrelated to this work. Consultative work by Kathryn M. Edwards for X-4 Pharma, Seqirus, Moderna, Pfizer, Merck, Roche, Novavax, Brighton Collaboration was serving on Safety and Monitoring Boards. Consultative work by Donna S. Hummel for Merck was for eDMC monitoring for clinical trial., (Published by Elsevier Ltd.)

Background: Following the authorization and recommendations for use of the U.S. COVID-19 vaccines, the Centers for Disease Control and Prevention (CDC)'s Immunization Safety Office (ISO) responded to inquiries and questions from public health officials, healthcare providers, and the general public on COVID-19 vaccine safety., Methods: We describe COVID-19 vaccine safety inquiries, by topic, received and addressed by ISO from December 1, 2020-August 31, 2022., Results: Of the 1978 COVID-19 vaccine-related inquiries received, 1655 specifically involved vaccine safety topics. The most frequently asked-about topics included deaths following vaccination, myocarditis, pregnancy, and reproductive health outcomes, understanding or interpreting data from the Vaccine Adverse Event Reporting System (VAERS), and thrombosis with thrombocytopenia syndrome., Conclusions: Inquiries about vaccine safety generally reflect issues that receive media attention. ISO will continue to monitor vaccine safety inquiries and provide accurate and timely information to healthcare providers, public health officials, and the general public., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Ltd.)

Background: COVID-19 vaccines may be co-administered with other recommended vaccines, including seasonal influenza vaccines. However, few studies have evaluated the safety of co-administration of mRNA COVID-19 and seasonal influenza vaccines., Objective: To describe reports to the Vaccine Adverse Event Reporting System (VAERS) after co-administration of mRNA COVID-19 and seasonal influenza vaccines., Methods: We searched the VAERS database for reports of adverse events (AEs) following co-administration of mRNA COVID-19 and seasonal influenza vaccines and following a first booster dose mRNA COVID-19 vaccine alone, during July 1, 2021-June 30, 2022. We assessed the characteristics of these reports and described the most frequently reported MedDRA preferred terms (PTs). Clinicians reviewed available medical records for serious reports and reports of adverse events of special interest (AESI) and categorized the main diagnosis by system organ class., Results: From July 1, 2021 through June 30, 2022, VAERS received 2,449 reports of adverse events following co-administration of mRNA COVID-19 and seasonal influenza vaccines. Median age of vaccinees was 48 years (IQR: 31, 66); 387 (15.8%) were classified as serious. Most reports (1,713; 69.3%) described co-administration of a first booster dose of an mRNA COVID-19 vaccine with seasonal influenza vaccine. The most common AEs among non-serious reports were injection site reactions (193; 14.5%), headache (181; 13.6%), and pain (171; 12.8%). The most common AEs among reports classified as serious were dyspnea (38; 14.9%), COVID-19 infection (32; 12.6%), and chest pain (27; 10.6%)., Discussion: This review of reports to VAERS following co-administration of mRNA COVID-19 and seasonal influenza vaccines did not reveal any unusual or unexpected patterns of AEs. Increased reporting of certain events (e.g., COVID-19 disease) was expected. CDC will continue to monitor the safety of co-administration of mRNA COVID-19 and seasonal influenza vaccines, including co-administration involving bivalent mRNA COVID-19 booster vaccines that have been recommended for people ages ≥ 6 months in the United States., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Ltd.)

Background: In December, 2020, two mRNA-based COVID-19 vaccines were authorised for use in the USA. We aimed to describe US surveillance data collected through the Vaccine Adverse Event Reporting System (VAERS), a passive system, and v-safe, a new active system, during the first 6 months of the US COVID-19 vaccination programme., Methods: In this observational study, we analysed data reported to VAERS and v-safe during Dec 14, 2020, to June 14, 2021. VAERS reports were categorised as non-serious, serious, or death. Reporting rates were calculated using numbers of COVID-19 doses administered as the denominator. We analysed v-safe survey reports from days 0-7 after vaccination for reactogenicity, severity (mild, moderate, or severe), and health impacts (ie, unable to perform normal daily activities, unable to work, or received care from a medical professional)., Findings: During the study period, 298 792 852 doses of mRNA vaccines were administered in the USA. VAERS processed 340 522 reports: 313 499 (92·1%) were non-serious, 22 527 (6·6%) were serious (non-death), and 4496 (1·3%) were deaths. Over half of 7 914 583 v-safe participants self-reported local and systemic reactogenicity, more frequently after dose two (4 068 447 [71·7%] of 5 674 420 participants for local reactogenicity and 4 018 920 [70·8%] for systemic) than after dose one (4 644 989 [68·6%] of 6 775 515 participants for local reactogenicity and 3 573 429 [52·7%] for systemic). Injection-site pain (4 488 402 [66·2%] of 6 775 515 participants after dose one and 3 890 848 [68·6%] of 5 674 420 participants after dose two), fatigue (2 295 205 [33·9%] participants after dose one and 3 158 299 participants [55·7%] after dose two), and headache (1 831 471 [27·0%] participants after dose one and 2 623 721 [46·2%] participants after dose two) were commonly reported during days 0-7 following vaccination. Reactogenicity was reported most frequently the day after vaccination; most reactions were mild. More reports of being unable to work, do normal activities, or of seeking medical care occurred after dose two (1 821 421 [32·1%]) than after dose one (808 963 [11·9%]); less than 1% of participants reported seeking medical care after vaccination (56 647 [0·8%] after dose one and 53 077 [0·9%] after dose two)., Interpretation: Safety data from more than 298 million doses of mRNA COVID-19 vaccine administered in the first 6 months of the US vaccination programme show that most reported adverse events were mild and short in duration., Funding: US Centers for Disease Control and Prevention., Competing Interests: Declaration of interests We declare no competing interests., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Background: Bexsero® (GlaxoSmithKline) is a four-component Neisseria meningitidis serogroup B vaccine (MenB-4C). It was licensed in the United States in 2015 for use among individuals ages 10-25 years. We aimed to assess the post-licensure safety profile of MenB-4C by examining reports received in the Vaccine Adverse Event Reporting System (VAERS)., Methods: VAERS is a national passive surveillance system for adverse events (AEs) following immunization that uses the Medical Dictionary for Regulatory Activities to code reported AEs and the Code of Federal Regulations to classify reports by seriousness. In this case series, we analyzed U.S. reports involving MenB-4C received between January 23, 2015 through December 31, 2018. We used Empirical Bayesian data mining to identify MenB-4C/AE combinations reported at least twice as often as expected., Results: VAERS received 1,867 reports following MenB-4C administration, representing 332 reports per million doses distributed. Most reports were for females (59%), with a median age of 17 years (interquartile range: 16-18 years); 40% of reports described simultaneous administration of other vaccines. The majority of reports were classified as non-serious (96%). The most commonly reported AEs were injection site pain (22%), pyrexia (16%), and headache (16%). Data mining identified disproportionate reporting for "injected limb mobility decreased" secondary to injection site reactions, including extensive swelling of the vaccinated limb and injection site pain., Conclusions: Analysis of passive surveillance data from over 5.6 million doses of MenB-4C distributed in the United States did not reveal new safety concerns. The large majority of reports were classified as non-serious and the reported AEs were generally consistent with the safety experience described in clinical studies and the product's package insert. While our results are reassuring, continued post-marketing surveillance is warranted., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Ltd.)

Background: Myopericarditis after vaccination has been sporadically reported in the medical literature. Here, we present a thorough descriptive analysis of reports to a national passive vaccine safety surveillance system (VAERS) of myopericarditis after vaccines licensed for use in the United States., Methods: We identified U.S. reports of myopericarditis received by VAERS during 1990-2018 that met a published case definition for myopericarditis or were physician-diagnosed. We stratified analysis by age group (<19, 19-49, ≥50 years), describing reports by serious/non-serious status, sex, time to symptom onset after vaccination, vaccine(s) administered, and exposure to other known causes of myopericarditis. We used Empirical Bayesian data mining to detect disproportionate reporting of myopericarditis after vaccination., Results: VAERS received 620,195 reports during 1990-2018: 708 (0.1%) met the case definition or were physician-diagnosed as myopericarditis. Most (79%) myopericarditis reports described males; 69% were serious; 72% had symptom onset ≤ 2 weeks postvaccination. Overall, smallpox (59%) and anthrax (23%) vaccines were most commonly reported. By age, among persons aged < 19 years, Haemophilus influenzae type b (22, 22%) and hepatitis B (18, 18%); among persons aged 19-49 years smallpox (387, 79%); among persons aged ≥ 50 years inactivated influenza (31, 36%) and live attenuated zoster (19, 22%) vaccines were most commonly reported. The vaccines most commonly reported remained unchanged when excluding 138 reports describing other known causes of myopericarditis. Data mining revealed disproportionate reporting of myopericarditis only after smallpox vaccine., Conclusions: Despite the introduction of new vaccines over the years, myopericarditis remains rarely reported after vaccines licensed for use in the United States. In this analysis, myopericarditis was most commonly reported after smallpox vaccine, and less commonly after other vaccines., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Ltd.)

Background: Underreporting is a limitation common to passive surveillance systems, including the Vaccine Adverse Event Reporting System (VAERS) that monitors the safety of U.S.-licensed vaccines. Nonetheless, previous reports demonstrate substantial case capture for clinically severe adverse events (AEs), including 47% of intussusception cases after rotavirus vaccine, and 68% of vaccine associated paralytic polio after oral polio vaccine., Objectives: To determine the sensitivity of VAERS in capturing AE reports of anaphylaxis and Guillain-Barré syndrome (GBS) following vaccination and whether this is consistent with previous estimates for other severe AEs., Methods: We estimated VAERS reporting rates following vaccination for anaphylaxis and GBS. We used data from VAERS safety reviews as the numerator, and estimated incidence rates of anaphylaxis and GBS following vaccination from the Vaccine Safety Datalink (VSD) studies as the denominator. We defined reporting sensitivity as the VAERS reporting rate divided by the VSD incidence rate. Sensitivity was reported as either a single value, or a range if data were available from >1 study., Results: VAERS sensitivity for capturing anaphylaxis after seven different vaccines ranged from 13 to 76%; sensitivity for capturing GBS after three different vaccines ranged from 12 to 64%. For anaphylaxis, VAERS captured 13-27% of cases after the pneumococcal polysaccharide vaccine, 13% of cases after influenza vaccine, 21% of cases after varicella vaccine, 24% of cases after both the live attenuated zoster and quadrivalent human papillomavirus (4vHPV) vaccines, 25% of cases after the combined measles, mumps and rubella (MMR) vaccine, and 76% of cases after the 2009 H1N1 inactivated pandemic influenza vaccine. For GBS, VAERS captured 12% of cases after the 2012-13 inactivated seasonal influenza vaccine, 15-55% of cases after the 2009 H1N1 inactivated pandemic influenza vaccine, and 64% of cases after 4vHPV vaccine., Conclusions: For anaphylaxis and GBS, VAERS sensitivity is comparable to previous estimates for detecting important AEs following vaccination., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Ltd.)

Background: Since the last review of vaccine safety surveillance data for erythema multiforme (EM), Stevens Johnson syndrome (SJS), SJS/TEN, and toxic epidermal necrolysis (TEN) (EM/SJS/TEN), over 37 new vaccines have been introduced in the United States. We sought to describe reported EM/SJS/TEN after vaccines during 1999-2017., Methods: We identified U.S. reports of EM/SJS/TEN received by the Vaccine Adverse Event Reporting System (VAERS) during 1999-2017. We stratified analysis by condition (EM, SJS, or TEN), and analyzed reports by serious or non-serious status, sex, age group, time from vaccination to symptom onset, exposure to known causes of EM/SJS/TEN, and vaccines administered. We used Empirical Bayesian data mining to detect vaccine-AE pairs reported more frequently than expected., Results: Of 466,027 reports to VAERS during 1999-2017, we identified 984 reports of EM, 89 reports of SJS, 6 reports of SJS/TEN, and 7 reports of TEN. Few reports of EM (9%), and most reports of SJS (52%), SJS/TEN (100%), and TEN (100%) were serious. Overall, 55% of reports described males, 48% described children aged < 4 years; 58% of EM/SJS/TEN occurred ≤ 7 days after vaccination. Few reports (≤5%) described exposure to known causes of EM/SJS/TEN. Overall, childhood vaccines (e.g., combined measles, mumps, and rubella vaccine) were most commonly reported. We identified 6 deaths; 4 were exposed to medications associated with EM/SJS/TEN. EM after smallpox vaccine was reported disproportionately among people aged 19-49 years., Conclusions: EM/SJS/TEN were rarely reported after vaccination; data mining identified a known association between EM and smallpox vaccine., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Ltd.)

Background: Since 2010, petitioner claims of shoulder injury related to vaccine administration (SIRVA) to the National Vaccine Injury Compensation Program (VICP) have been increasing., Objective: To conduct a scientific review of clinical characteristics of SIRVA petitions to the VICP., Methods: We queried the VICP's Injury Compensation System database for medical reports of alleged SIRVA and SIRVA-like injuries. Medical reports are summaries of petitioner claims and supporting documentation along with a VICP clinician reviewer diagnosis and assessment of criteria for concession. We conducted a descriptive analysis of SIRVA petitioner claims recommended by the VICP for concession as SIRVA injuries., Results: We identified 476 petitioner claims recommended for concession. Claims per year increased from two in 2011, the first full year in the analytic period, to 227 in 2016. Median age was 51 years, 82.8% were women, and median body mass index was 25.1 (range 17.0-48.9). Four hundred cases (84.0%) involved influenza vaccine. Pharmacy or store (n = 168; 35.3%) was the most common place of vaccination followed by doctor's office (n = 147; 30.9%). Fewer than half of cases reported a suspected administration error; 172 (36.1%) reported 'injection too high' on the arm. Shoulder pain, rotator cuff problems, and bursitis were common initial diagnoses. Most (80.0%) cases received physical or occupational therapy, 60.1% had at least one steroid injection, and 32.6% had surgery. Most (71.9%) healthcare providers who gave opinions on causality considered the injury was caused by vaccination. A minority (24.3%) of cases indicated that symptoms had resolved by the last visit available in medical records., Conclusions: Most conceded claims for SIRVA were in women and involved influenza vaccines. Injection too high on the arm could be a factor due to the risk of injecting into underlying non-muscular tissues. Healthcare providers should be aware of proper injection technique and anatomical landmarks when administering vaccines., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019 Elsevier Ltd. All rights reserved.)