Pfizer’s pill, Paxlovid, that is used to treat Covid-19, has retained its 89 precent efficacy rate at preventing people from being hospitalized and from dying in the results from a study that included 2,246 high-risk patients.
Oral treatments are important because of how easy they are to administer to people that are infected compared to drugs which must be injected or given intravenously.
Experts were relieved that the results from Pfizer held up, though they all explained the need to examine the data more fully.
“Being protected from hospitalization is obviously wonderful,” Andrew Pekosz said. “That number was great. It was conserved in that last analysis which really points to this being an important weapon in our fight against Covid-19 especially as we see new variants that are going to be lowering the efficacy number.”
Pfizer reported data from another study in adults infected with Covid that have a normal risk of developing severe effects. This group included vaccinated people. The study did not meet its goal, of raising the sustained alleviation of symptoms. The study is continuing, but Pfizer said that there was a lower number of hospitalizations in that group, although the numbers were low.
In the high-risk patient study, called EPIC-HR, only 5 of 697 patients who took a five-day course of the pill were hospitalized or died, compared to 44 of 682 who were given a placebo. The Paxlovid group had no deaths, however there were 9 in the placebo group. Both groups had adverse events occur at similar rates. Paxlovid patients were less likely to suffer from a severe problem or to stop taking the pill due to a side effect. Patients who were unvaccinated and had at least one underlying medical condition that raised their risk of Covid-19 were considered high risk. These included being overweight, being over 65, or having heart disease.
The low-risk study, called EPIC-SR, had 2 of 333 patients who were given a five-day course of the drug hospitalized compared to 8 of 329 who took the placebo. A second analysis showed similar results, Pfizer said. Adverse events were close between the drug and placebo.
Paxlovid, if approved, would be administered as two pills of Paxlovid and one of ritonavir, which is another antiviral, two times a day for five days. Ritonavir can interact with a number of other medicines, which could create problems for its use.
A big worry, said Topol, is supply of the drug. Pfizer will have 200,000 courses available this year and 80 million available by next year. But he is worried that it may not be enough based on the waves of Covid that may hit worldwide.
Pfizer believes Paxlovid will keep its potency against the new variant, Omicron, based on in vitro data that shows the pill has a key protease enzyme in Omicron. With that said, she noted, antiviral assays have not yet been developed for the variant.
“We have all put a lot of time into developing this antiviral,” she said, “and we really hoped we would not need it.”
Author: Scott Dowdy