Abstract: The coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a global pandemic and presents a global public health threat. Although there are huge efforts to understand and treat COVID-19, it would be preferable to prevent the infection and development of clinical disease. Current COVID-19 vaccines include inactivated SARS-CoV-2 vaccine, adenovirus-vectored vaccine, mRNA vaccine, and protein subunit vaccine; the vaccines may elicit robust humoral immune responses and cellular immune responses among a great majority of adults in trials by inducing high spike-specific antibodies and neutralizing antibodies, and strong Th1 cytokine responses. The protective efficacies of the vaccines for COVID-19 are more than 70% in the adults. There are many different factors impacting on protective efficacy of the vaccines.