This longitudinal observational study collected weekly data for 20 weeks, from March 21 to August 9, 2020, from more than 70,000 UK adults aged 18 or older through the COVID-19 Social Study. Recruitment used mailing lists, print and digital media, social media, and recruitment companies to increase participation among people with low incomes, unemployment, limited education, and other vulnerable groups, including older adults, caregivers, and people with preexisting mental illness. The final sample comprised 36,520 respondents in England who provided demographic information.