1. Volunteers without clinical evidence of COVID-19 infection aged 18 years and older. 2. Participants who are at high risk of SARS-CoV-2 infection, defined as adults whose locations or circumstances put them at appreciable risk of exposure to SARS-CoV-2 and COVID-19. 3. Must have a mobile phone and access to the Internet for data collection purposes. 4. Participants who are willing and able to provide informed consent via an electronic consent process.

1. Volunteers without clinical evidence of COVID-19 infection aged 18 years and older. 2. Participants who are at high risk of SARS-CoV-2 infection, defined as adults whose locations or circumstances put them at appreciable risk of exposure to SARS-CoV-2 and COVID-19. 3. Must have a mobile phone and access to the Internet for data collection purposes. 4. Participants who are willing and able to provide informed consent via an electronic consent process.