The collaborative outcomes study on health and functioning during infection times in adults (COH-FIT-Adults): Design and methods of an international online survey targeting physical and mental health effects of the COVID-19 pandemic

•The Collaborative Outcome study on Health and Functioning during Infection Times (COH-FIT) is the broadest survey on COVID-19 impact to date, involving over 230 researchers and 120 institutions across the six continents.•COH-FIT is an online anonymous survey, cross-sectional at the individiual level, but longitudinal at the population level, and has a multi-wave structure.•COH-FIT is available in 30 languages, being inclusive towards linguistic and ethnic minorities.•COH-FIT collects responses from adults, adolescents, and children starting from 6 years old.•COH-FIT collects both representative sample via polling agencies, and non-representative samples via snowball/non-probability recruiting approach.•COH-FIT has been collecting over 150,000 responses from over 150 countries, from the six continents from April 26th, 2020 to July 23rd, 2021.•Take the survey at www.coh-fit.com. . High-quality comprehensive data on short-/long-term physical/mental health effects of the COVID-19 pandemic are needed. . The Collaborative Outcomes study on Health and Functioning during Infection Times (COH-FIT) is an international, multi-language (n=30) project involving >230 investigators from 49 countries/territories/regions, endorsed by national/international professional associations. COH-FIT is a multi-wave, on-line anonymous, cross-sectional survey [wave 1: 04/2020 until the end of the pandemic, 12 months waves 2/3 starting 6/24 months threreafter] for adults, adolescents (14-17), and children (6-13), utilizing non-probability/snowball and representative sampling. COH-FIT aims to identify non-modifiable/modifiable risk factors/treatment targets to inform prevention/intervention programs to improve social/health outcomes in the general population/vulnerable subgrous during/after COVID-19. In adults, co-primary outcomes are change from pre-COVID-19 to intra-COVID-19 in well-being (WHO-5) and a composite psychopathology P-Score. Key secondary outcomes are a P-extended score, global mental and physical health. Secondary outcomes include health-service utilization/functioning, treatment adherence, functioning, symptoms/behaviors/emotions, substance use, violence, among others. . Starting 04/26/2020, up to 14/07/2021 >151,000 people from 155 countries/territories/regions and six continents have participated. Representative samples of ≥1,000 adults have been collected in 15 countries. Overall, 43.0% had prior physical disorders, 16.3% had prior mental disorders, 26.5% were healt