The trial’s results suggest that Pfizer’s drug surpasses Merck & Co Inc’s (MRK.N) pill, molnupiravir, which was shown last month to halve the chance of dying or being hospitalized for COVID-19 patients at high risk of serious illness.
Pfizer’s pill, with the brand name Paxlovid, could secure U.S. regulatory approval by the end of the year. Pfizer said it plans to submit interim trial results to the Food and Drug Administration (FDA) before the Nov. 25 U.S. Thanksgiving holiday. The trial was stopped early due to its high success rate.
President Joe Biden said the U.S. government has secured millions of doses of Pfizer’s drug.
“If authorized by the FDA we may soon have pills that treat the virus in those who become infected,” Biden said. “The therapy would be another tool in our toolbox to protect people from the worst outcomes of COVID.”
Shares in Pfizer, which also makes one of the mostly widely used COVID-19 vaccines, rose 11% to close at $48.61. Merck’s fell 10% to close at $81.61. Shares of vaccine makers took a hit, with Moderna Inc (MRNA.O), Pfizer’s German partner BioNTech SE and Novavax (NVAX.O) all down 11-21%.
Pfizer’s pill is given in combination with an older antiviral called ritonavir. The treatment consists of three pills given twice daily. It has been in development for nearly two years.
Antivirals need to be given as early as possible, before an infection takes hold, to be most effective.
The planned analysis of 1,219 patients in Pfizer’s study examined hospitalizations or deaths among people diagnosed with mild to moderate COVID-19 with at least one risk factor for developing severe disease, such as obesity or older age.
Among those given Pfizer’s drug within three days of symptom onset, the pill lowered the chances of hospitalization or death for adults at risk of developing severe COVID-19 by 89% compared to those receiving a placebo. Among these patients, 0.8% were hospitalized and none died by 28 days after treatment, compared to a 7% hospitalization rate and seven deaths in the placebo group.
Rates were similar for patients treated within five days of symptoms: 1% of the treatment group was hospitalized, compared to 6.7% for the placebo group, which included 10 deaths. Pfizer said that represents 85% effectiveness at preventing hospitalization or death.