Early Mortality After the First Dose of COVID-19 Vaccination: A Target Trial Emulation.

BACKGROUND: Vaccine hesitancy persists alongside concerns about the safety of coronavirus disease 2019 (COVID-19) vaccines. We aimed to examine the effect of COVID-19 vaccination on risk of death among US veterans. METHODS: We conducted a target trial emulation to estimate and compare risk of death up to 60 days under two COVID-19 vaccination strategies: vaccination within 7 days of enrollment versus no vaccination through follow-up. The study cohort included individuals aged ≥18 years enrolled in the Veterans Health Administration system and eligible to receive a COVID-19 vaccination according to guideline recommendations from 1 March 2021 through 1 July 2021. The outcomes of interest included deaths from any cause and excluding a COVID-19 diagnosis. Observations were cloned to both treatment strategies, censored, and weighted to estimate per-protocol effects. RESULTS: We included 3 158 507 veterans. Under the vaccination strategy, 364 993 received vaccine within 7 days. At 60 days, there were 156 deaths per 100 000 veterans under the vaccination strategy versus 185 deaths under the no vaccination strategy, corresponding to an absolute risk difference of -25.9 (95% confidence limit [CL], -59.5 to 2.7) and relative risk of 0.86 (95% CL, .7 to 1.0). When those with a COVID-19 infection in the first 60 days were censored, the absolute risk difference was -20.6 (95% CL, -53.4 to 16.0) with a relative risk of 0.88 (95% CL, .7 to 1.1). CONCLUSIONS: Vaccination against COVID-19 was associated with a lower but not statistically significantly different risk of death in the first 60 days. These results agree with prior scientific knowledge suggesting vaccination is safe with the potential for substantial health benefits.

Incidence Rates and Clinical Characteristics of Patients With Confirmed Myocarditis or Pericarditis Following COVID-19 mRNA Vaccination: Experience of the Veterans Health Administration Through 9 October 2022.

Background: Although the benefits outweigh the risks, COVID-19 vaccines have been associated with an increased risk of myocarditis and pericarditis. This report is based on a national US veteran population with confirmed myocarditis/pericarditis following mRNA COVID-19 vaccines according to the near real-time active surveillance program of Veterans Affairs. Methods: This study is based on a cohort evaluation of all adults administered ≥1 mRNA COVID-19 vaccine, including boosters, in the Veterans Health Administration between 14 December 2020 and 9 October 2022. ICD-10-CM diagnosis codes were used to identify potential safety signals in near real time through a database analysis. All potential cases of myocarditis/pericarditis identified in the database analysis underwent in-depth chart review and case validation by a team of pharmacists and expert clinicians. Our main outcome was the incidence rate of confirmed myocarditis/pericarditis among vaccine recipients (overall and those aged 18-39 years) within 21 days of a first, second, or booster dose of a mRNA COVID-19 vaccine. We calculated the ratio of observed events among COVID-19 vaccine recipients over expected events from historical vaccine recipient controls (2015-2020) in the Veterans Health Administration. We used confirmed cases to calculate incidence rates and 95% CIs. Results: Through 9 October 2022, 3 877 453 doses of BNT162b2 (Pfizer-BioNTech) and 4 221 397 doses of mRNA-1273 (Moderna) were administered as first or second dose across Veterans Affairs, and 1 012 561 BNT162b2 and 1 156 160 mRNA-1273 booster doses were administered. Among all doses, the rapid cycle analysis identified 178 potential cases of myocarditis/pericarditis among vaccinees of any age and 22 potential cases among those aged 18-39 years. Of these, 33 cases, including 6 among those 18-39 years old, were confirmed after in-depth chart review and validation, corresponding with an overall incidence rate per million ranging from 0.46 (95% CI, .01-2.55) for Moderna dose 1 to 6.91 (95% CI, 2.78-14.24) for Pfizer booster. Among those aged 18-39, incidence rates ranged from 7.1 (95% CI, .18-39.56) for Moderna dose 2 to 19.76 (95% CI, 5.38-50.58) for Pfizer dose 2. Patients with confirmed cases were hospitalized for a mean 4.1 days (range, 1-15). The final disposition for 32 (97%) of 33 cases was discharge to home. Conclusions: This report is a real-world demonstration of the Veterans Affairs' active surveillance system for vaccines. Although the rapid cycle analysis initially identified 178 potential cases of myocarditis/pericarditis, only 1 of 5 cases was confirmed to be related to a COVID-19 vaccine after chart review. These findings highlight the paramount importance of active surveillance and chart validation for rare but serious adverse events related to COVID-19 vaccines.