ABSTRACT
COVID-19 vaccines were designed to stimulate an immunological response, producing neutralizing antibodies against the SARS-CoV-2 spike protein. Vaccine variants such as mRNA, viral vector, whole-cell inactivated virus, and protein subunit vaccines, have been reported to be efficacious in phase III trials and have gained emergency use approval in many countries. However, several adverse effects are reported in certain types of vaccines. All vaccines are being expedited by some Asian countries as part of their national immunization programs. This review primarily discussed the selected manufacturers of the COVID-19 vaccines used and their effectiveness in early-adopting Asian countries. The effectiveness in reducing the infection rate and safety of COVID-19 vaccines in Japan, Thailand, Singapore and Malaysia was also analyzed based on the available data. Strategies that can be used to speed up the vaccination rate in reducing the number of COVID-19 cases were also evaluated.