What is Paxlovid, the treatment against covid-19?

(CNN)– As soon as doctors determined on Thursday that President Biden had covid-19, the White House doctor prescribed the antiviral Paxlovid.

Considered a game changer when it was licensed in December because of its strong performance in reducing the risk of severe covid-19, Paxlovid — in combination with vaccines and boosters — is believed to be one of the best ways to protect people at high risk for serious illness.

Because of these developments, Biden’s experience with the coronavirus should be very different from that of President Donald Trump, who was in the hospital for days in October 2020.

What is Paxlovid?

Paxlovid is an antiviral drug from Pfizer that uses two drugs: nirmatrelvir and ritonavir. It comes in pill form.

The US Food and Drug Administration (FDA) has authorized Paxlovid for emergency use in people 12 years of age and older who weigh at least 39 kilograms (88 pounds) and who have covid-19 mild to moderate but are at high risk for severe disease.

The standard regimen is three pills twice a day for five days.

Biden’s risk of serious illness

Biden’s age, 79, puts him at risk of severe covid-19. But the US Centers for Disease Control and Prevention (CDC) says that for older adults who are fully vaccinated and boosted, the risks of hospitalization and death are significantly reduced.

Biden has double reinforcement. He received his initial vaccination series prior to his inauguration in January 2021. He received his first booster in September and his second booster on March 30.

Biden’s symptoms are mild. She has a runny nose, occasional cough, and some fatigue.

The president’s physician, Dr. Kevin O’Connor, said in a letter Friday that Biden had a temperature of 99.4 °F (37.4 °C) on Thursday night. He took Tylenol and her temperature has been normal ever since.

Because Paxlovid can interact with other medications, O’Connor temporarily withdrew Biden from Crestor and Eliquis, two heart medications he takes for pre-existing conditions. Doctors say there is no short-term risk from stopping these medications.

How does Paxlovid work?

Paxlovid suppresses the coronavirus by blocking an enzyme that helps the virus reproduce inside the body.

As with all antivirals, the treatment is thought to work best if people start taking it within five days of the first symptoms.

How successful is it?

Clinical trials of Paxlovid showed that it reduced the risk of hospitalization and death by 88% when administered within five days of symptom onset.

However, the drug was tested in unvaccinated people during the rise of the delta variant, so the results could be different for people taking the pills now, with the omicron-dominant variant.

Pfizer has said the drug works well against omicron, and additional lab studies have shown similar results.

“Joe Biden is vaccinated and twice boosted, which in itself reduces his risk of serious illness, hospitalization, or death,” Dr. Megan Ranney, an emergency physician and academic dean of public health at Brown University, said Thursday. . “You add Paxlovid, which reduces — even in vaccinated people — that risk of hospitalization by another 80% to 90%, and the chance of something bad happening to him is practically zero.”

What about the side effects?

Paxlovid side effects are considered mild and may include diarrhea, increased blood pressure, muscle aches, stomach pain, nausea, and altered sense of taste.

Allergic reactions include hives, difficulty swallowing or breathing, swelling of the mouth, tightness in the throat, hoarseness, and rash. Liver problems are also possible.

Doctors say the drug is generally well tolerated.

How about a relapse?

“There have been people who have relapsed from Paxlovid. That is, although Paxlovid suppresses [los síntomas] over a period of time while taking it, five days after that, some people have a recurrence of some of their symptoms. So we’re going to have to keep an eye on that,” Dr. William Schaffner, a professor in the division of infectious diseases at Vanderbilt University Medical Center, said Thursday.

In May, the CDC issued a health advisory to inform doctors of the potential for COVID-19 relapse with Paxlovid, but the agency continues to recommend its use.

Cases of relapse two to eight days after initial recovery have been reported. Most people who had new symptoms said they resolved in about three days, even without additional treatment.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said that when he contracted Covid-19, he took a five-day course of Paxlovid and felt better, but relapsed with worse symptoms. He took the medication again and recovered.

Ranney and other doctors say they don’t like to think of it as a rebound infection. Rather, Paxlovid does a good job of suppressing the virus and preventing the damage it can cause, but the virus may not be completely cleared from the body and may re-emerge.

Some scientists believe that some people metabolize Paxlovid faster than others and may need longer treatment. The investigation is still ongoing.

“We don’t see people who end up with those symptoms that need hospitalization after taking Paxlovid, so I don’t like the term ‘relapse’ because it scares people into stopping Paxlovid,” Ranney said.

The CDC says it doesn’t believe the return of symptoms is a sign of reinfection or development of resistance to Paxlovid. The number of people recovering is nominal, early research shows.

Dr. Ashish Jha, White House Covid-19 response coordinator, downplayed concerns that Biden might relapse while taking Paxlovid.

“The best clinical data we have suggests it happens 5% to 7% of the time,” Jha said Friday. “It’s pretty rare, and the good news is that even when that happens, people do fine.”