Publication date: Nov 01, 2024

We evaluated all-cause healthcare utilization among those with vaccine-associated myocarditis, compared to vaccinees without post-vaccination myocarditis. We conducted a retrospective cohort study in individuals aged 12 and older who received COVID-19 mRNA vaccination in British Columbia. Exposure was defined as an ED visit or hospitalization for myocarditis within 21 days post-vaccination. The primary outcome was healthcare utilization. Ratios of rate ratios (RRRs) for exposure-associated healthcare utilization were calculated using a difference-in-differences (DiD) analysis. In the post-index period, the exposed and unexposed groups showed substantial utilization rate difference (RD = 15. 30 [95% CI, 14. 47-16. 13). A 51% overall increase in healthcare utilization was observed over 18 months among exposed individuals (RRR, 1. 51 [95%CI, 1. 08-2. 11]). In the initial six months, healthcare utilization surpassed the 18-month estimate, exhibiting a 125% increase (RRR, 2. 25 [95%CI, 1. 43-3. 52]), while the last 12 months showed no statistically significant change (RRR, 1. 03 [95%CI, 0. 72-1. 47]). An additional 9. 1 (95%CI, 8. 53-9. 71) visits per person were attributed to vaccine-associated myocarditis over 18 months (total excess = 938. 26 healthcare visits). The initial surge in healthcare visits post-exposure, mainly outpatient follow-ups, followed by a return to baseline rates, indicates a positive prognosis and supports the vaccine’s safety profile.

Semantics

Original Article