New collaborative study to address key questions about COVID-19 A new nationwide study of more than 50,000 individuals is underway to determine factors that predict disease severity and long-term health impacts of COVID-19. Researchers at the University of Colorado Anschutz Medical Campus are part of the NIH-funded study, the Collaborative Cohort of Cohorts for COVID-19 Research (C4R) Study, which includes 37 academic medical centers across the country. Participants in C4R are currently enrolled in 14 long-term studies at cohort institutions. The new collaborative study will be able to answer important questions about COVID-19 that cannot be answered by smaller, individual studies that have been set up to study COVID-19.