One of the components of Paxlovid is ritonavir, a drug that is also used in some HIV treatment regimens. The risk of ritonavir resistance when used as treatment for COVID-19 in a patient with HIV is largely theoretical. Ritonavir resistance has been observed in some patients taking it as part of their HIV treatment, so some are concerned that this resistance may develop during COVID-19 treatment too.
However, the duration of ritonavir exposure for COVID-19 treatment is very short (5 days), leaving minimal time for resistance to develop. Additionally, the use of ritonavir for HIV treatment is becoming more rare, so resistance is less of a concern.
Patients with controlled HIV should not be at increased risk for developing resistance as their disease is controlled. Patients with undiagnosed or uncontrolled HIV may have a very small and unlikely chance of developing resistance, and the potential benefits of COVID-19 treatment are likely greater than these risks.