In comments to Bloomberg published on May 3, 2022, Pfizer chief executive officer Albert Bourla suggested that patients who experience a relapse of symptoms after finishing a course of the company's COVID-19 antiviral, Paxlovid, should take a second course of the drug. Yet the emergency use authorisation issued by the US Food and Drug Administration (FDA) stipulates that Paxlovid is “not authorized for use longer than five consecutive days”. On May 4, John Farley, director of the Office of Infectious Diseases at the FDA, reiterated this message.“There is no evidence of benefit at this time for a longer course of treatment... or repeating a treatment course of Paxlovid in patients with recurrent COVID-19 symptoms following completion of a treatment course”, stated Farley.

The US Government pays around US $530 for each 5-day course of Paxlovid. The drug is a combination of ritonavir plus the novel protease inhibitor PF-07321332. The emergency use authorisation was granted late last year, on the strength of results from the phase 2–3 trial showing that Paxlovid reduces the risk of hospitalisation or death for high-risk patients by 88%, compared with the placebo, if given within 5 days of symptom onset. The trial only recruited unvaccinated individuals. But three-quarters of the UK population and two-thirds of the US population are now fully vaccinated against COVID-19.