Pfizer’s COVID-19 Antiviral Cuts Hospitalization, Deaths

Pfizer ceased further enrollment in the phase 2/3 study of its investigational novel COVID-19 oral antiviral candidate, Paxlovid (ritonavir), after positive findings.

The pharma maker’s scheduled interim analysis showed a significant 89% reduction in risk of COVID-19-related hospitalization or death compared with placebo, Pfizer said in a news release.

Albert Bourla

“[This] is a real game-changer in the global efforts to halt the devastation of this pandemic. These data suggest that our oral antiviral candidate, if approved or authorized by regulatory authorities, has the potential to save patients’ lives, reduce the severity of COVID-19 infections, and eliminate up to nine out of 10 hospitalizations,” said Albert Bourla, Pfizer’s chairman and CEO.

Pfizer plans to submit the data as part of its ongoing rolling submission to the FDA for emergency use authorization (EUA) as soon as possible, the pharma maker said.

If approved or authorized, Paxlovid would be the first oral antiviral of its kind, a specifically designed SARS-CoV-2-3CL protease inhibitor, Pfizer said.

“Upon successful completion of the remainder of the EPIC clinical development program and subject to approval or authorization, it could be prescribed more broadly as an at-home treatment to help reduce illness severity, hospitalizations, and deaths, as well as reduce the probability of infection following exposure, among adults,” Pfizer noted.

Paxlovid demonstrated potent antiviral in vitro activity against circulating variants of concern, as well as other known coronaviruses, suggesting its potential as a therapeutic for multiple types of coronavirus infections, Pfizer added.

SVB Leerlink analysts expect Paxlovid to be approved first via EUA, with distribution initially relatively tightly — and federally — controlled, analyst Geoffrey Porges wrote in a research note. However, by the end of the first quarter of 2022, “we would expect it to be available commercially (accelerated review) and then accessible to consumers and their medical providers across the country.”

“Pfizer has already committed to large-scale manufacturing at risk, but has not confirmed their available supply for 2022. We would expect first shipments to be in the channel by year-end, with up to 1 billion courses available during 2022,” Porges added.

The pharma maker’s EPIC-HR double-blind study of non-hospitalized adult patients with COVID-19 who are at high risk of progressing to severe illness demonstrated that 0.8% of patients who received Paxlovid were hospitalized through day 28 and there were no deaths, compared with a 7% hospitalization rate in patients who received placebo. There were seven deaths in the placebo group.

Similar reductions in COVID-19-related hospitalization or death were observed in patients treated within five days of symptom onset. One percent of patients who received Paxlovid were hospitalized through day 28 with no deaths, compared with 6.7% of patients who received a placebo and 10 subsequent deaths.

Pfizer has an antiviral available to reduce the risk of death and hospitalization by nearly 90%, Porges wrote. “This result is clearly good news for Pfizer shareholders, and initially negative news for the developers of other COVID antivirals, and is inevitably also going to reduce the need for COVID antibodies, other than as long-term prophylaxis for high risk (immuno-compromised) individuals.”