The purpose of this study is to learn about the effects of the study medicine called Paxlovid \[nirmatrelvir-ritonavir/PF-07321332\], for the potential treatment of COVID-19. This study will use patient health records in Ontario, to find people who were sick with COVID-19 and visited a pharmacist to be treated, anytime from December 1st, 2022, to March 31st, 2024. To be included in our study, the people must be over 18 years of age and be registered in the Ontario health system for at least one year. People were not included in our study if they have been pregnant in the past year or have serious kidney or liver disease. We will separate the people in the study into two groups: those who received treatment with Paxlovid \[nirmatrelvir-ritonavir/PF-07321332\] and those who received no treatment. We will monitor their healthcare visits or if they die for any reason, for up to 60 days after the date that they visited their pharmacist. Then we will compare participant experiences when they are taking the study medicine to when they are not. This will help us determine if the study medicine is effective.