Dec. 22, 2021 -- The FDA on Wednesday granted emergency use authorization for a new antiviral pill to treat people with symptomatic COVID-19.

Pfizer’s ritonavir plus nirmatrelvir, name brand Paxlovid, can now be taken by patients ages 12 and up who weigh at least 88 pounds 

The antiviral is only for people who test positive for the coronavirus, and who are at high risk for severe COVID-19, including hospitalization or death. It is available by prescription only and should be taken as soon as possible after diagnosis and within 5 days of the start of symptoms.

Paxlovid is taken as three tablets together orally twice a day for 5 days, for a total of 30 tablets.

Possible side effects include a reduced sense of taste, diarrhea, high blood pressure, and muscle aches.

The authorization arrives as U.S. cases of the Omicron variant are surging, some monoclonal antibody treatments are becoming less effective, and as Americans struggle to maintain some sense of tradition and normalcy around the holidays.

Paxlovid joins remdesivir as an available antiviral to treat COVID-19. Remdesivir is fully approved by the FDA but is given only as an IV in a hospital.  

The COVID-19 antiviral pills come with some obvious advantages, including greater convenience for consumers -- such as home use -- and the potential to expand treatment for people in low- and middle-income countries.

'An Exciting Step Forward'

The EUA for Pfizer’s new drug has been highly anticipated, and news of its impending authorization circulated on social media on Tuesday. Eric Topol, MD, called the development an "exciting step forward." Topol is editor-in-chief of Medscape, WebMD’s sister site for health care professionals.

He and many others also expected the FDA to grant emergency use authorization for an antiviral from Merck. But there was no immediate word Wednesday if that was still going to happen.

"The emergency use authorization today of Paxlovid (nirmatrelvir plus ritonavir) is a great step forward in our struggle against COVID-19," agreed Prathit Kulkarni, MD.

It is important to take the antiviral within 5 days of starting to have symptoms due to COVID-19, Kulkarni told Medscape Medical News when asked to comment.   

In addition, "the highest benefit in preventing hospitalization or death was seen in patients who did not have evidence of prior immunity against SARS-CoV-2 through vaccination or prior infection. Benefit was also seen in younger and older patients, as well as folks with and without certain medical conditions," said Kulkarni, assistant professor of medicine in the section of infectious diseases at Baylor College of Medicine in Houston.

Paxlovid has the potential to interact with many other important medications, Kulkarni noted, "so checking with the prescribing clinician about these possibilities will be important for anyone who will be taking the medication."

Indicated for People 12 and Older

"It's hopeful but it's not the answer to everything. My major concern is for people thinking this is the cure-all," Kunjana Mavunda, MD, a pediatric pulmonologist consultant at multiple KIDZ Medical Services locations throughout South Florida, said when also asked to comment.

Clearly with Omicron, a lot of adults and children are getting sick, added Mavunda. Because the Pfizer COVID-19 pill is authorized for ages 12 and older, many children are not eligible.

People starting the regimen early enough in the course of COVID-19 disease to have maximum effect is another potential concern. "The earlier it's taken after infection, the better," Mavunda said. Furthermore, she hopes cost will not be an impediment when ritonavir is made available in low- and middle-income countries.

Ramping Up Manufacturing

"The FDA authorization of the oral drug, Paxlovid, represents a real leap forward in the fight against Covid-19. With the Omicron variant spreading like wildfire, having a new tool to protect against severe disease is critical," Shoshana Ungerleider, MD, an internal medicine physician at Crossover Health Medical Group in San Francisco, says. .

Prioritizing access to the antiviral medication for people at higher risk for developing severe disease will be key, she said. "At this point, we believe this pill should work against the Omicron variant, but supply is very limited. My sincere hope is that this new treatment will allow more people with COVID-19 to be treated at home, helping ease the burden on hospitals which will likely only get worse over the coming weeks"

President Joe Biden addressed availability and distribution in a statement. "Recognizing that this pill takes time to make given the complex scientific process, production will ramp up in the months ahead. We will have over 250,000 treatment courses available to us in January and we will be working with states to ensure those are being distributed equitably and fairly and that our hardest-hit communities are reached," he said.

An Accelerated Authorization?

The FDA's authorization for Pfizer’s antiviral comes about 5 weeks after the company submitted an application to the agency. In its submission, the company said a study showed the pill reduced by 89% the rate of hospitalization and death for people with mild to moderate COVID-19 illness.

In April 2021, Pfizer announced its antiviral pill for COVID-19 could be available by year's end. In September, an official at the National Institutes of Allergy and Infectious Diseases seconded the prediction.

Merck filed its EUA application with the FDA in October. The company included results of its phase III study showing the treatment was linked to a 50% reduction in COVID-19 hospitalizations.

Interestingly, in September, Merck announced the findings of laboratory studies suggesting that molnupiravir would work against variants of the coronavirus because the agent does not target the virus's spike protein. At the time, Delta was the dominant variant in the U.S.

Faith-Based Purchasing

The U.S. government has already recognized the potential of these oral therapies, at least in terms of pre-orders.

Last month, it announced intentions to purchase $1 billion worth of Merck’s molnupiravir, adding to the $1.2 billion worth of the pills the U.S. ordered in June 2021. Also in November, the government announced it would purchase 10 million courses of the Pfizer pill at an estimated cost of $5.3 billion.

The government pre-orders of the antiviral pills for COVID-19 are separate from the orders for COVID-19 vaccines. Most recently, the Biden administration announced it will make 500 million tests for coronavirus infection available to Americans for free in early 2022.