The pandemic of coronavirus disease 2019 (COVID-19) seriously threatens human health and development. In response to this global public health event, SARS-CoV-2 vaccine with different techniques has been put into emergency use. This paper introduces the technique of SARS-CoV-2 vaccine, and elaborates the efficacy of COVID-19 vaccine against various mutant strains and its use in high-risk population. It is found that the effectiveness of the existing vaccines to mutant strains has declined to some extent, which suggests that the impact of mutant strains should be paid attention to. The existing vaccines lack sufficient clinical data for the elderly, pregnant women and other high-risk groups, so it is necessary to carry out research on vaccination for high-risk groups as soon as possible.