Coronavirus disease 2019 (COVID-19) continues to be a pandemic threat with new mutations of the viral agent (SARS-CoV 2) that are generating a constant state of attention in manifold countries. Innovative drugs, such as vaccines can sustain, as far as possible, immunity of people and decrease negative effects in society. The study here, using data of vaccines and confirmed cases of COVID-19 between countries from March to May 2021, clarifies different optimal levels of vaccination associated with the growth of pandemic wave for reducing infected individuals in society. Findings reveal that a vaccination campaign in the initial phase of pandemic wave has a lower optimal level of doses administered per 100 inhabitants, but the growth of pandemic wave moves up the optimal level of vaccines from 58.5 in March to more than 86 doses per 100 people in May 2021. This study suggests that the optimal strategy and response to pandemic crisis is a rapid vaccination rollout, before the takeoff of pandemic wave, for an effective response to reduce numbers of COVID-19 related infected individuals and deaths and negative effects of pandemic crisis on environment and socioeconomic systems.