To tackle the pandemic of the novel coronavirus (severe acute respiratory syndrome coronavirus 2; SARS-CoV-2), the international society, including Japan, has been actively promoting vaccination for SARS-CoV-2. To effectively utilize these vaccines, clinical trials have been conducted to evaluate their safety and efficacy. For efficacy evaluation, prevention rate of symptomatic novel coronavirus infections (corona virus disease 2019; COVID-19) between placebo groups and investigational vaccine groups has been the key parameter to evaluate the novel COVID-19 vaccines. This approach is based on a consensus among international regulatory authorities. Compared to several months ago, the public vaccination campaign for COVID-19 has substantially progressed in many countries. This makes it difficult to conduct clinical trials, which have placebo control arms, anywhere in the world because of ethical problems in administering a placebo during a pandemic. Therefore, the new international consensus among regulatory authorities is that immunogenicity bridging studies between the new COVID-19 vaccines that are being developed and approved COVID-19 vaccines may be needed when placebo-controlled studies are no longer feasible. In the future, the number of unvaccinated people worldwide is expected significantly decrease; thus, the issue of how to evaluate additional immunization for those who have completed the initial immunization remains to be addressed. This would require new international convergence. The development of COVID-19 vaccines and their evaluation would have to be updated, considering the social situation and vaccine coverage.