How Long that a SARS‑CoV‑2 Variant Delay Impacts Required Period to Achieve Herd Immunity?

Abstract

Dear Editor, The coronavirus disease (COVID‑19) vaccine is the present preventive tool for COVID‑19 containment. Mass immunization is required for achieving herd immunity. If herd immunity is reached, a successful COVID‑19 containment is expected.[1,2] In general, the targeted population size that herd immunity will achieve is mainly based on the basic reproduction number and is generally estimated as 75%.[1,2] Regarding the required period to achieve the impact of herd immunity depends on many facts including the targeted population size (unit: %), base local infection prevalence (unit: %), vaccination rate (unit: %), efficacy of vaccine (unit: %), and monthly infection rate (unit: %).