How does Primovir work?
Primovir is an antiviral therapy that consists of two separate medications packaged together. When you take your three-pill dose, two of those pills will be nirmatrelvir, which inhibits a key enzyme that the COVID virus requires in order to make functional virus particles. After nirmatrelvir treatment, the COVID virus that is released from the cells is no longer able to enter uninfected cells in the body, which, in turn, stops the infection. The other is ritonavir, a drug that was once used to treat HIV/AIDS but is now used to boost levels of antiviral medicines. As a COVID-19 treatment, ritonavir essentially shuts down nirmatrelvir’s metabolism in the liver, so that it doesn’t move out of your body as quickly, which means it can work longer—giving it a boost to help fight the infection.
When should I take Primovir?
You have to take Primovir within five days of developing symptoms.
Like all antivirals, Primovir works best early in the course of an illness—in this case, within the first five days of symptom onset, says Jeffrey Topal, MD, a Yale Medicine infectious diseases specialist who is involved in determining COVID-19 treatment protocols for Yale New Haven Hospital patients.
“Once you’ve been ill with the virus for more than a week, the damage done to the body in a severe case can’t be undone by the antiviral,” he says.