Opinion EDITORIAL Temporal Associations Between Immunization With the COVID-19 mRNA Vaccines and Myocarditis The Vaccine Safety Surveillance System Is Working Ann Marie Navar, MD, PhD; Elizabeth McNally, MD, PhD; Clyde W. Yancy, MD, MSc; Patrick T. O’Gara, MD; Robert O. Bonow, MD, MS Prior reports of adverse events following immunization for vaccines.7-9 A well-developed multipronged postmarketing sur- measles, mumps, and rubella, later deemed unsubstanti- veillance system monitors vaccine safety after approval and ated, raised significant public alarm and led to vaccine resis- is designed to detect extremely rare events that occur in less tance—an effect that lingers to this day. In light of this legacy, than 1 in 1 million vaccinees. This system includes the Vac- as well as ongoing fears re- cine Adverse Events Reporting System, a voluntary and eas- Editorial lated to vaccination leading to ily accessible reporting system that archives possible vaccine variable uptake, especially in adverse effects10; the Vaccine Safety Datalink, a hospital net- populations at higher risk for work designed to evaluate for increases in background rates Related articles COVID-19, the editorial deci- of certain possible events11; and the Clinical Immunization sion to publish 2 articles re- Safety Assessment Project, in which the CDC partners with 7 porting the association of myocarditis following COVID-19 mes- medical research centers to leverage expertise in senger RNA (mRNA) vaccination was not taken lightly.1,2 vaccine safety.12 For COVID-19 vaccines, the CDC also set up The 2 case series by Montgomery and coworkers1 and Kim the v-safe system, which is offered to vaccine recipients and and coworkers2 in the current issue of JAMA Cardiology de- uses a smartphone app to collect symptoms following scribe a temporal association between myocarditis and vac- immunization.13 In addition, medical researchers across the cination against SARS-CoV-2 with the Pfizer-BioNTech and country, including those highlighted in the Brief Reports pub- Moderna mRNA vaccines. This temporal association does not lished in JAMA Cardiology,1,2 form an informal network of vac- establish causality, especially because a myocarditis-like syn- cine safety surveillance capable of detecting potential clus- drome has been seen following SARS-CoV-2 infection. Rather, ters of events for further investigation. Increased engagement these case series highlight the need for additional surveil- with this system by the public will help provide continued criti- lance and investigation. cal data for vaccine safety monitoring. In short, a web of safety The editors recognize that publication of these data may and surveillance supports vaccine administration, and based contribute to additional public concern regarding immuniza- on these case reports, that system is working. tion because reports of myocarditis following COVID-19 mRNA Persons with cardiovascular disease are at high risk of com- vaccination have already been reported in the news3 and in plications from COVID-19, and physicians caring for these pa- peer-reviewed publications.4 Furthermore, concerns regard- tients should encourage immunization and help guide pa- ing vaccine safety are the most common reason cited for lack tients in their decision-making. In one study, 66% of older of vaccination.5 However, as highlighted in the accompany- adults reported that they would talk to their health care pro- ing Editorial from immunization safety experts at the US fessional first before making a decision regarding Centers for Disease Control and Prevention (CDC),6 clinicians immunization.14 In addition to discussing the risks of COVID-19 discussing immunization with patients should recognize that infection and the efficacy of vaccines, physicians should iden- these case series suggest that the symptomatic events consis- tify patient concerns regarding vaccine safety and be pre- tent with myocarditis are still very rare and appear to be self- pared to discuss these risks with patients. limiting. Given the risks of COVID-19, including the risk of myo- The rarity of these events, including the identified link be- carditis from COVID-19 infection, the editors do not believe tween the even rarer cerebral venous sinus thrombosis fol- these case reports are sufficient to interrupt the march to- lowing the Johnson & Johnson SARS-CoV-2 vaccine, should re- ward maximal vaccination against SARS-CoV-2 as expedi- assure the public that the system is indeed functioning as tiously as possible. designed.15 Strikingly, the potential adverse effects reported Importantly, we endorse a different perspective: these data thus far are extremely rare. Although the clinical trials of SARS- are exemplary of a successful formal and informal vaccine sur- CoV-2 vaccines showed robust safety, the widespread imple- veillance system, a system about which most of our readers mentation in which nearly 150 million individuals in the US may be unaware. Phase 3 clinical trials of vaccine efficacy and have been fully vaccinated in 6 months is unheralded. As the safety are able to detect common adverse effects but are not pandemic continues and new variants emerge, maintaining powered to detect more rare events, and it is noteworthy that confidence in the vaccine safety surveillance system will be myocarditis was not reported in the trials of the mRNA critical to maintain public trust in the vaccine. A key part of jamacardiology.com (Reprinted) JAMA Cardiology Published online June 29, 2021 E1 © 2021 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/24/2021 Opinion Editorial this confidence includes transparency, with careful critical re- rare adverse events. Moving forward, this level of due dili- view and publication of possible links between vaccination and gence will remain a key editorial priority. ARTICLE INFORMATION 2. Kim HW, Jenista ER, Wendell DC, et al. Patients 8. Baden LR, El Sahly HM, Essink B, et al; COVE Author Affiliations: UT Southwestern Medical with acute myocarditis following mRNA COVID-19 Study Group. Efficacy and safety of the mRNA-1273 Center, Dallas, Texas (Navar); Associate Editor, vaccination. JAMA Cardiol. Published online June 29, SARS-CoV-2 vaccine. N Engl J Med. 2021;384(5): JAMA Cardiology (Navar); Northwestern Feinberg 2021. doi:10.1001/jamacardio.2021.2828 403-416. doi:10.1056/NEJMoa2035389 School of Medicine, Chicago, Illinois (McNally, 3. Mandavilli A. C.D.C. is investigating a heart 9. Frenck RW Jr, Klein NP, Kitchin N, et al; Yancy, Bonow); Section Editor, JAMA Cardiology problem in a few young vaccine recipients. New C4591001 Clinical Trial Group. Safety, (McNally); Deputy Editor, JAMA Cardiology (Yancy, York Times. Published May 22, 2021. Accessed May immunogenicity, and efficacy of the BNT162b2 O’Gara); Brigham and Women’s Hospital, Harvard 23, 2021. https://www.nytimes.com/2021/05/22/ Covid-19 vaccine in adolescents. N Engl J Med.2021. Medical School, Boston, Massachusetts (O’Gara); health/cdc-heart-teens-vaccination.html doi:10.1056/NEJMoa2107456 Editor, JAMA Cardiology (Bonow). 4. Marshall M, Ferguson ID, Lewis P, et al. 10. Vaccine Adverse Event Reporting System. Corresponding Author: Ann Marie Navar, MD, PhD, Symptomatic acute myocarditis in seven Accessed June 8, 2021. https://vaers.hhs.gov UT Southwestern Medical Center, 5323 Harry Hines adolescents following Pfizer-BioNTech COVID-19 11. Vaccine Safety Datalink. Accessed June 8, 2021. Blvd, Dallas, TX 75201 (ann.navar@ vaccination. Pediatrics. 2021;e2021052478. doi:10. https://www.cdc.gov/vaccinesafety/ utsouthwestern.edu). 1542/peds.2021-052478 ensuringsafety/monitoring/vsd/index.html Published Online: June 29, 2021. 5. The Delphi Group at Carnegie Mellon University 12. Clinical Immunization Safety Assessment (CISA) doi:10.1001/jamacardio.2021.2853 in partnership with Facebook. COVID-19 Symptom Project. Accessed June 8, 2021. https://www.cdc. Conflict of Interest Disclosures: Dr Navar reports Survey: Topline Report on COVID-19 Vaccination in gov/vaccinesafety/ensuringsafety/monitoring/ grants from Janssen and personal fees from the United States: Survey waves 6-8, January cisa/index.html 10–February 27, 2021. Published March 12, 2021. Janssen, AstraZeneca, Sanofi, and Pfizer outside 13. V-safe After Vaccination Health Checker. the submitted work. Dr McNally reports personal Accessed June 8, 2021. https://www.cmu.edu/ delphi-web/surveys/CMU_Topline_Vaccine_Report_ Accessed June 8, 2021. https://www.cdc.gov/ fees from Amgen, AstraZeneca, Avidity Biosciences, coronavirus/2019-ncov/vaccines/safety/vsafe.html 4D Molecular Therapeutics, Cytokinetics, Janssen, 20210312.pdf PepGen, Pfizer, Invitae, and Tenaya Therapeutics 6. Shay DK, Shimabukuro TT, DeStefano F. 14. Nikolovski J, Koldijk M, Weverling GJ, et al. outside the submitted work and is the founder of Myocarditis occurring after immunization with Factors indicating intention to vaccinate with a Ikaika Therapeutics. No other disclosures were mRNA-based COVID-19 vaccines. JAMA Cardiol. COVID-19 vaccine among older U.S. adults. PLoS One. reported. Published online June 29, 2021. doi:10.1001/ 2021;16(5):e0251963. doi:10.1371/journal.pone. jamacardio.2021.2821 0251963 REFERENCES 7. Polack FP, Thomas SJ, Kitchin N, et al; C4591001 15. See I, Su JR, Lale A, et al. US case reports of cerebral venous sinus thrombosis with . Montgomery J, Ryan M, Engler R, et al. Clinical Trial Group. Safety and efficacy of the 1 thrombocytopenia after Ad26.COV2.S vaccination, Myocarditis following immunization with mRNA BNT162b2 mRNA Covid-19 vaccine. N Engl J Med. March 2 to April 21, 2021. JAMA. Published online COVID-19 vaccines in members of the US military. 2020;383(27):2603-2615. doi:10.1056/ April 30, 2021. doi:10.1001/jama.2021.7517 JAMA Cardiol. Published online June 29, 2021. NEJMoa2034577 doi:10.1001/jamacardio.2021.2833 E2 JAMA Cardiology Published online June 29, 2021 (Reprinted) jamacardiology.com © 2021 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/24/2021.