New Special Issue of Vaccines on Immunogenicity, Efficacy and Safety of COVID-19 vaccines and COVID-19 vaccination strategies. This Special Issue of Vaccines seeks to collect high-quality articles presenting the results of studies on immunogenicity, efficacy and safety of COVID-19 vaccines; post-marketing assessment of COVID-19 vaccine immunogenicity, efficacy and safety; COVID-19 vaccination programs challenges related to efficacy and safety; and knowledge, perception and communication of COVID-19 vaccine efficacy and safety.