Worldwide SARS-CoV-2 Omicron variant infection: Emerging sub-variants and future vaccination perspectives

The coronavirus disease 2019 (COVID-19) pandemic has sparked widespread concern globally, particularly with the Omicron variant and its sub-lineages emerging as the predominant cause of infection for nearly two years. Taiwan's successful containment of COVID-19, underscored by broad vaccine coverage, the utilization of anti-viral therapeutics, and timely response strategies, has resulted in reduced excess mortality. Moreover, there is a crucial need for a phased exit strategy, balancing efforts to curtail disease transmission with the mitigation of socioeconomic impacts from rigorous measures. In this review, we examined the evolution and the epidemiological landscape of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron sub-variants in Taiwan as well as other countries of the world. We also critically evaluated the effectiveness of COVID-19 vaccines against various SARS-CoV-2 variants. Additionally, we addressed the advantages of heterologous immunization strategies, fluctuations in neutralizing antibody titers, and complexities in establishing protective correlates among swiftly mutating viral variants.