Symptomatic Myocarditis After Pfizer Covid-19 Vaccination

Widely considered safe, effective, and essential for pathogenic immunity, vaccines have proven to be one of the most important discoveries to date in medicine. Adverse reactions to vaccines are typically trivial but there have been extremely rare reports of vaccine induced myocarditis, particularly with the Tdap vaccine. This is thought to be due to a hypersensitivity reaction. In efforts to combat the SARS-CoV-2, prompt response from Pfizer-BioNTech and Moderna lead to vaccine development with a novel method, synthesized from modified messenger RNA. Despite minimal side effects on initial trials, reports of vaccine induced myocarditis have resulted. A majority of these cases occurred following subsequent doses for those previously inoculated. A descriptive study published in JAMA in January 2022 reviewed the Vaccine Adverse Event Reporting System (VAERS) in collaboration with the CDC described only 1626 cases of myocarditis, of which the majority occurred within days of the second dose. This review was limited by reviewing a passive reporting syndrome with variable quality data and without follow up data post diagnosis of myocarditis. Here we present a case of myocarditis occurring less than 24 hours after the second dose of Pfizer-BioNTech vaccine with 3 month follow up. A 23 year old man received his second dose of the COVID-19 vaccine in the morning. Within a few hours he experienced chest pain, chills, weakness, and fatigue. These dissipated by 7pm. He is a member of the National Guard and during drills the next day experienced stabbing substernal chest pain for which he sought evaluation. The pain radiated into his left jaw, worse with deep inspiration and worse in the left lateral decubitus position. He is a 1 PPD smoker with no personal or family history or cardiac disease. A friction rub was heard on physical exam. His troponin I peaked at 2.6ng/mL. His EKG showed normal sinus rhythm, a TTE showed a normal EF with no pericardial effusion. He was given aspirin 81 mg and started on a heparin drip for possible NSTEMI. The next day his pain decreased and a cardiac MRI demonstrated no inflammation. His serum coxsackie and parvovirus titers were negative. He was instructed to continue the aspirin, limit exercise for 8 weeks, and stop smoking. Upon follow up 3 months later the patient denied any recurrent chest pain and was advised to continue the aspirin. But the original bout of myocarditis limited his participation in the National Guard. Our case illustrates that exposure to an immunological trigger, the COVID-19 vaccine, leading to myocarditis was extremely short compared to typical cases of viral induced or vaccine hypersensitivity reaction. A proposed mechanism is molecular mimicry between the spike protein and myocardial contraction proteins. It also demonstrates that the vaccine can cause morbidity in patients, especially younger males. It also exemplifies that this may be a short lived phenomenon, long term follow up is still needed. With the rate of vaccination increasing, there needs to be a low threshold to consider myocarditis in young adults who have new chest pain after receiving an mRNA based vaccine.