Pill 88% effective if given early, says Pfizer

Pfizer on Tuesday said its Covid-19 antiviral pill Paxlovid reduced hospitalisation or death by 88-89% compared to placebo in the high risk patients in clinical trials and that it works against the highly mutated Omicron variant.

Final results of Paxlovid demonstrated reduction of hospitalisation or death by 89% among high-risk patients treated within three days of symptom onset and 88% among those who started treatment within five days, the US drug maker said.

There were no deaths in the Paxlovid arm compared to placebo in non-hospitalised, high-risk adults with Covid-19, it said.

The efficacy among patients treated within five days of symptom onset improved from 85% observed in the interim analysis, Pfizer said. The final results were based on analysis of all 2,246 adults enrolled who were enrolled by November 4, 2021. The trial was conducted in North and South America, Europe, Africa, and Asia, with 41% of patients located in the US.

Around 0.7%, or five out 697, patients who received Paxlovid were hospitalised through Day 28, while 6.5%, or 44 out of 682, patients who received placebo were hospitalised or died. Pfizer also said its antiviral pill worked in laboratory studies against the Omicron variant, which has been classified as a variant of concern by the WHO.

"Recent in-vitro data confirm that nirmatrelvir is a potent inhibitor of the Omicron 3CL protease, which, combined with existing in-vitro antiviral and protease inhibition data from other variants of concern (VoCs) including Delta, indicates that Paxlovid will retain robust antiviral activity against current VoCs as well as other coronaviruses," the company said.