Heard of that new pill to treat COVID-19? Here is what you need to know!


TL;DR: The FDA gave emergency use authorization to Paxlovid, an antiviral pill, that may reduce the risk of hospitalization and death for people who have mild to moderate COVID-19 infections and are at increased risk of getting severely ill. While this is super exciting news, it is not a magic answer to stopping the pandemic. Supply is still limited and there are some caveats to keep in mind when taking this medication.

Let’s start with the clinical trial data (everyone’s favorite!):

The FDA’s emergency use authorization is based on limited data from a trial looking at a little over 2,000 adults with symptomatic COVID-19 who did not need to be hospitalized. All these folks also had at least one risk factor for progression to severe illness from COVID-19, like having chronic lung disease, weakened immune systems, or being over the age of 60. NONE of them had been vaccinated or had a prior COVID-19 infection. They all had symptoms for no more than 5 days (this is important). Participants were randomized to get Paxlovid or a placebo. In the Paxlovid group, 8 (0.8%) people were hospitalized and 0 people died. In the placebo group, 66 (6.3%) were hospitalized and 13 (1.1%) people died. This means that for this very specific population, Paxlovid reduced the risk of hospitalization by about 89%. In other words, to prevent one hospitalization, you would need to treat 18 people with mild to moderate COVID-19 who have no prior immunity and are at high risk of severe illness (This is called the number needed to treat, or NNT). This is a very good NNT. The NNT to prevent one death is 87 (also great). This risk reduction is similar to the risk reduction seen in sotrovimab (85% relative reduction) and remdesivir (87% relative reduction) and way better than molnupiravir (30% relative reduction).

How do you take it?

Paxlovid is actually two different types pills (both equally challenging to say 😉): nirmatrelvir tablets and ritonavir tablets. You take two of the nirmatrelvir tablets (for a total dose of 300 mg) and one ritonavir tablet (which is 100 mg) all together twice a day. That means you take 3 pills twice daily for 5 days (that’s a grand total of 30 pills). It should be started as soon as possible after diagnosis and within 5 days of getting any symptoms.

How does it work?

Nirmatrelvir prevents a specific part of SARS-CoV-2 (called Mpro) from doing its job which prevents the virus from replicating. Ritonavir is typically a medication used to treat HIV, but in this instance, it stops your body from metabolizing the nirmatrelvir so it can do its thing against COVID-19. That’s why you need to take both.

What about those caveats you mentioned?

➡️ It is only authorized for adults and kids age 12 and up who weigh at least 40 kg (88 pounds). This is not available for younger kids.

➡️ It is only available by prescription from a healthcare provider.

➡️ It needs to be taken within 5 days of getting symptoms. With a shortage of tests, delays in results, and lack of access to healthcare providers, that may be a tricky target to hit for a lot of folks.

➡️ The virus circulating at the time of the study was the Delta variant. We don’t know how well this works with Omicron.

➡️ There isn’t data about safety or efficacy for pregnant or lactating people. Or for people under the age of 18.

➡️ People with severe liver disease and severe kidney disease cannot take this medication.

➡️ There are A LOT of drug interactions with other medications people might be taking. It will be important to talk with a healthcare professional about all the meds you might be taking before starting Paxlovid.

➡️ Taking Paxlovid with uncontrolled or undiagnosed HIV infection may lead to HIV drug resistance, making the HIV harder to treat.

➡️ The most common side effects include changes in sense of taste, diarrhea, high blood pressure and muscle aches.

➡️ Paxlovid can decrease the effectiveness of hormonal birth control and it is recommended people use a back up method of contraception (but to be fair, while sick with COVID-19 is probably not the best time to be having sex anyway).

➡️ There is only a small supply of Paxlovid. For now, most health departments are limiting this med to people at the highest risk.

➡️ People taking Paxlovid still need to isolate and follow all the same safety measures to prevent risk of infecting other people.

➡️ People still need to watch out for worsening illness and seek immediate medical attention if symptoms are getting worse.

While it is great to have another tool in the belt, this is not enough to stop the pandemic in its tracks. Keeping up all the layers of prevention and vaccination are still important.

Stay Safe. Stay Sane.

Those Nerdy Girls


NIH Treatment Guidelines Summary of Paxlovid

US Test To Treat

STAT News Article

FDA EUA Fact Sheet

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