A Computable Phenotype Algorithm for Postvaccination Myocarditis/Pericarditis Detection Using Real-World Data: Validation Study - Matthew Deady; Raymond Duncan; Matthew Sonesen; Renier Estiandan; Kelly Stimpert; Sylvia Cho; Jeffrey Beers; Brian Goodness; Lance Daniel Jones; Richard Forshee; Steven A Anderson; Hussein Ezzeldin (Journal of Medical Internet Research)