COVID-19 Immunity and Changes Over Time

The risk of household spread of SARS-CoV-2 hinges on both the transmission dynamics of the virus circulating in the community as well as the seroprotection pattern of constituent members, which can be attributed to vaccination and previous infections. This study is conceptualised to assess the dynamicity of SARS-CoV-2 risk at the household level, through monitoring the pattern of seroprotection, in conjunction with the vaccination coverage, history of infection and exposure risk in the setting of Hong Kong.

Inclusion Criteria: * adults of age 18 or above, or children under the age of 18 with informed consent of the legal guardian * normally residing in Hong Kong * could communicate in spoken and written Chinese and/or English Exclusion Criteria: * individuals with mental illness * prisoners