Factors associated with SARS-CoV-2 seropositivity among undiagnosed adults

This study aimed to assess factors associated with natural SARS-CoV-2 infection among undiagnosed Singaporean adults in the late stage of the pandemic. Snowball sampling was used to recruit a convenient sample of adults for a serology study between March 2022 and May 2023. Participants completed a one-time survey and a serology test assessing the presence of Anti-N antibodies. 9.8% of 539 previously undiagnosed participants had been naturally infected. This study further adds value through examination of public perception towards personal and policy level on protective measures that were mostly implemented for the first time in Singapore during COVID-19, enabling calibration of communication and implementation strategies if the need to implement similar public health measures in the future. Understanding SARS-CoV-2 transmission mode, having a stronger sense of social responsibility by voluntarily staying at home when symptomatic were significantly associated with lower odds of seropositivity. Further studies are warranted to validate the relevance of these factors for public health programmes.