A timeline of COVID-19 vaccines and myocarditis.
2020
Sept. 22, 2020: U.S. Centers for Disease Control and Prevention (CDC) identifies myocarditis as an adverse event of special interest, or a potential side effect.
Oct. 30, 2020: U.S. Food and Drug Administration (FDA) identifies myocarditis as an adverse event of special interest.
December 2020: One case of pericarditis reported to the U.S. Vaccine Adverse Event Reporting System (VAERS), which is co-managed by the CDC and FDA.
Dec. 11, 2020: FDA authorizes the Pfizer-BioNTech vaccine for Americans 16 and older.
Dec. 13, 2020: CDC launches V-safe, a new vaccine safety monitoring system, without including myocarditis as an option in the adverse events list.
Dec. 18, 2020: FDA authorizes the U.S. government-backed Moderna vaccine for Americans 18 and older.
2021
2021: Myocarditis cases spike in the U.S. military.
January 2021: 28 cases of myocarditis, pericarditis, or myopericarditis reported to VAERS.
January 2021: First U.S. military member experiences postvaccination myocarditis, according to a study published months later.
January 2021: First cases of postvaccination myocarditis recorded in Israel.
January 2021: VAERS report processing is delayed due to unexpected spike in reports.
February 2021: 64 cases of myocarditis, pericarditis, or myopericarditis reported to VAERS, including two deaths.
Feb. 1, 2021: Israeli teenager is hospitalized with myocarditis after Pfizer vaccination, doctors say.
Feb. 18, 2021: Safety signal for myocarditis triggered in VAERS using CDC-endorsed method called Proportional Reporting Ratio.
Feb. 19, 2021: Safety signal for myocarditis triggered in VAERS using another method called Fisher’s Exact Test.
Feb. 24–25, 2021: CDC meets with its advisers but does not discuss COVID-19 vaccines.
Feb. 27, 2021: FDA authorizes Johnson & Johnson’s COVID-19 vaccine.
Feb. 28, 2021: Israeli officials privately alert CDC to “a large number of reports of myocarditis, particularly in young people, following the administration of the Pfizer vaccine.”
Feb. 28, 2021: 57 cases of myocarditis or pericarditis within seven days of vaccination in Pfizer’s database in document given to the FDA in April 2021 and not revealed to the public until November 2021.
March 2021: 54 cases of myocarditis, pericarditis, or myopericarditis reported to VAERS.
March 1, 2021: CDC officials disclose (pdf) that two postvaccination cases were identified in the Vaccine Safety Datalink (VSD), another CDC-run system.
March 2, 2021: CDC recommends Johnson & Johnson’s COVID-19 vaccine for adults.
March 3, 2021: Israeli authorities meet with hospital officials to discuss postvaccination heart problems.
March 4, 2021: Israeli officials confirm they’re investigating postvaccination pericarditis.
March 5, 2021: FDA holds meeting with its advisers. Myocarditis is not discussed.
March 6, 2021: Rutgers University becomes first major US school to announce COVID-19 vaccine mandate.
March 8, 2021: Australian health officials contact CDC about U.S. myocarditis cases.
March 9, 2021: U.S. internal memorandum says Israel received around 40 reports of postvaccination myocarditis. U.S. officials say some postvaccination cases were reported in the United States and acknowledge issues with passive surveillance such as underreporting. “Thus, FDA has not made a final determination regarding the causality between myopericarditis and the mRNA COVID-19 vaccines,” the memo stated.
March 20, 2021: First postvaccination myocarditis case report is published in the literature.
March 20, 2021: Pfizer contract with South Africa (pdf) says that “there may be adverse effects of the vaccine that are not currently known.”
March 31, 2021: Second postvaccination myocarditis case report published.
March 31, 2021: First death from postvaccination myocarditis reported in Israel. The deceased was a 22-year-old previously healthy woman.
