A Study to Learn About the Study Medicine (Nirmatrelvir Plus Ritonavir) in Pregnant Women With COVID-19

The purpose of this clinical trial is to learn about how study medicine (Paxlovid, which contains nirmatrelvir and ritonavir) is changed and eliminated from the body, as well as its safety, and the extent to which side effects can be tolerated for treatment of pregnant women with mild or moderate COVID-19 compared to non-pregnant women with mild or moderate COVID-19.

This study is seeking participants who:

• are expecting a healthy baby and are in their second or third trimester pregnancy and have mild or moderate COVID-19

• are not pregnant and have mild or moderate COVID-19.

All participants in this study will take Paxlovid by mouth every 12 hours for 5 days. We will study the experiences of people receiving the study medicine. This will help us decide if the study medicine is safe.

All participants will take part in this study for at least 34 days; pregnant participants will take part until their delivery, so that the study duration may be up to 6 months, depending on their delivery date.

During this time, participants will have 7to 8 visits and, if pregnant, a visit at delivery. Around 2 to 3 visits and the delivery visit will be done in person (at the clinic or at the participant's home). The other 5 visits may be done over the phone, unless in-person visit is necessary as decided by the doctor. Blood samples will be collected on the first 4 to 5 study visits (and at other study visits, if necessary).