Field and pharmacovigilance data so far have shown that these vaccines were immunogenic, effective, and very safe [39] . However, the frailty was timing and availability. Generally supplies came in later and in smaller amounts than forecasted, in part due to lower yield in growth of the vaccine virus strain than expected. Reduce and delay community spread somewhat at the earliest stage to allow better preparation for mitigation response [15] Completely prevent entry of infected individuals due to suboptimal sensitivity and asymptomatic (including infected and within incubation period) or subclinical presentation [16] Many countries did not attempt these measures because of logistics, stage of pandemic [22] or other cost-benefit considerations [16] China Hong Kong SAR Japan Personal protective measures (e.g., face masks, hand hygiene, cough etiquette, early self-isolation when ill) Reduce risk of infection to self and close contacts (if self is ill and infected) [27, 28] Have not been evaluated whether they can provide significant populationlevel protection