Pfizer COVID pill now authorized by FDA: It won't 'cure' omicron, but here's what it does

The FDA gave emergency use authorization to Pfizer's Paxlovid on Wednesday for treating COVID-19. It is the first oral antiviral treatment authorized for fighting the coronavirus.

Last week, Pfizer announced that Paxlovid reduces the risk of hospitalization or death by 89% if administered within three days of symptoms. Data also suggests that the pill will be effective against the new omicron variant. If given within five days, the pill still reduced the risk of severe reaction by 88%, up from an 85% efficacy rate reported in an interim analysis in November.

The "Pfizer pill" is actually a combination of two medications: the existing antiviral ritonavir with the newly developed drug nirmatrelvir (or PF-07321332). The two antivirals work together as a protease inhibitor to disrupt the replication of COVID-19 in infected patients. 

Many doctors and scientists hope that the Pfizer pill will change the course of the COVID-19 pandemic and save significant numbers of lives. However, the pill will not stop transmission COVID-19, and some are concerned that a new pill might actually hurt COVID-19 vaccination and mitigation efforts. Doctors note that any therapeutic pills should not replace vaccines as a first line of defense against COVID-19.

While COVID-19 vaccines are highly effective -- including against the newer omicron variant -- millions of Americans are still not vaccinated. According to a September report from the CDC, unvaccinated people are more than 10 times more likely to be hospitalized or die from the virus than those who are fully vaccinated.

Paxlovid "could have a meaningful impact on the lives of many," Pfizer CEO Albert Bourla said in a statement last week. "Emerging variants of concern, like omicron, have exacerbated the need for accessible treatment options for those who contract the virus ... We are confident that, if authorized or approved, this potential treatment could be a critical tool to help quell the pandemic."

The Paxlovid protocol requires taking two tablets of nirmatrelvir and one tablet of ritonavir, twice per day for five days. It promises to reduce the more severe symptoms of COVID-19 and will now be a new tool in the pandemic fight, along with the approved COVID vaccines from Moderna, Pfizer and Johnson & Johnson. 

"We have far more tools to fight this virus than we ever did just one year ago," Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention, said during a White House briefing last week.

Merck also has an antiviral drug recently authorized by the FDA, though it is nowhere near as effective as Paxlovid appears to be.

Here's what we know about Pfizer's antiviral pill. We'll update this story as more details emerge. For more on COVID-19, check out the latest on vaccine mandates, keeping your vaccine card handy and this year's flu season.

What is Pfizer's COVID-19 antiviral drug?

In the US, the three approved COVID vaccines can prevent infection. But for those already infected, antiviral drugs could reduce the odds of serious symptoms, hospitalization and death.

Nirmatrelvir, marketed under the brand name Paxlovid, is designed to block the activity of the SARS-CoV-2-3CL protease, an enzyme that the coronavirus needs to replicate. In clinical trials, taken in combination with ritonavir, a drug used to treat HIV, Paxlovid reduced the risk of hospitalization or death by 89% when taken within three days of symptoms, Pfizer said. (The ritonavir allows the medication to remain active in the body longer at higher concentrations.) 

If the Paxlovid is approved, two 150mg tablets would be administered at the first sign of symptoms or a positive COVID-19 test result and continued over a five-day treatment course.
The pill has proven effective against COVID-19 variants of concern, including delta and the newer omicron strain, Pfizer said.

During clinical trials, reported side effects between those taking Paxlovid and those taking a placebo were about the same, according to the pharmaceutical company.

When will Pfizer's COVID-19 pill be available?

Pfizer in November asked the FDA for emergency-use authorization for its antiviral drug and Bourla said he expected the FDA to make a decision by the end of 2021. If approved, Paxlovid is ready to go: "We have already shipped product into the US," Bourla said, "so [it] will be available this month if it's approved."

How does Paxlovid compare with molnupiravir, Merck's COVID-19 pill?

Merck applied for an emergency use authorization of its antiviral pill it developed with Ridgeback in mid-October and received authorization in November.

Merck has said its pill can reduce the risk of hospitalization and death by 30% if taken within five days of the onset of symptoms for people who have tested positive and are at higher risk of serious illness. 
The medication has already been given to patients in the UK as part of an ongoing national study, the BBC reports.

In anticipation of authorization in the US, Merck said it expects to produce 10 million courses of molnupiravir by the end of 2021, with at least 20 million in 2022.

Will Pfizer's drug be free?

President Joe Biden has said Pfizer's antiviral treatments will be "easily accessible and free" thanks to his administration already purchasing 10 million treatment courses. Separately, the government is purchasing 1.7 million courses of Merck's antiviral drug, molnupiravir, to administer if and when it is approved by the FDA.

For more on COVID-19, here's the latest on COVID-19 vaccines for kids, what to know about mixing and matching vaccines and what is happening with booster shots.

Will the drug's approval cause vaccination rates to decline? 

"This [89% efficacy rate] is equivalent to protection from the vaccine -- it's that good," Dr. Monica Gandhi, an infectious disease expert at the University of California, San Francisco, told CNET. "But during this pandemic, we've done everything in our power to get people to take the vaccine -- we've incentivized, cajoled, mandated. At this point, a year since the first vaccine was announced, I don't think we're going to change someone's mind."

Could COVID-19 medications lead to drug-resistant strains?

The overuse of some antibiotics has led to drug-resistant strains of diseases like MRSA, pneumonia, tuberculosis and gonorrhea, according to the World Health Organization. But Gandhi said that's unlikely to happen with Paxlovid because the course of treatment is so short -- only five days. 

"It won't put selective pressure on the virus to evolve," she said. "Plus, there will be real limits on who it's prescribed to: It won't be given out like crazy -- you'll have to have a positive COVID test and it will probably only be given to unvaccinated patients."