When COVID-19 first hit, the risk of being infected was much higher than the personal costs of getting the vaccine. In 2022, these considerations are very different, says Duke-NUS Centre for Outbreak Preparedness’ Dr Khoo Yoong Khean.The fourth COVID-19 jab has been made available for groups of people in Singapore since April, with the updated bivalent mRNA vaccine available to those aged 18 and above since Nov 7. The bivalent mRNA vaccine targets the ancestral SARS-CoV-2 virus as well as the Omicron variants, such as BA.1, BA.4/5. Because of the immune evasion properties of the Omicron variants, this updated vaccine...