• Woottichai Khamduang, PhD Assistant Professor, Faculty of Associated Medical Sciences, Chiang Mai University,

• Chaisiri Angkurawaranon, MD, PhD Assistant Professor, Faculty of Medicine Chiang Mai University,

• Kittiphan Chalom, MD. Preventive Medicine (Epidemiology) Chiang Mai Provincial Health Office/Director of Chai Prakan Hospital,

• Arunee Thitithanyanont, MD Associate Professor, Faculty of Science, Mahidol University

• Nopporn Apiwattanakul, MD, PhD Associate Professor, Faculty of Medicine Ramathibodi Hospital, Mahidol University

SARS-CoV-2 outbreak was first reported in the city of Wuhan, China, in December 2019. The WHO declared the virus a Public Health Emergency of International Concern (PHEIC) on 30 January 2020 and a pandemic on 11 March 2020. As of 1 March 2022, more than 578 million cases and 6.4 million deaths have been reported to WHO from all continents.The Thai partners in VERDI, Mahidol University and Chiang Mai University are both leading universities with accredited virology laboratories working to diagnose incident SARS CoV-2 infections in the community and are therefore ideally place to identify eligible participants to invite to participate in this study and enroll participants into this study. Both partners have the infrastructure and capacity to enroll, follow up study participants, securely collect, manage and analyze the data, collect transport and store samples and conduct sequencing of variants.

1) Assess the occurrence of SARS-CoV-2 infection in household members based on virological and serological evaluations, and disease symptoms

2) Estimate key transmission parameters of SARS-CoV-2 in Bangkok and Chiang Mai.

3) Identify SARS-CoV-2 variants at the beginning of each wave

4) Analyze associations between the characteristics described above and infection with different variants