What Is Paxlovid Rebound, and How Common Is It?

President Joe Biden began taking an oral treatment of Paxlovid immediately after he was diagnosed with Covid. Biden tested positive for COVID after finishing Paxlovid, but without any symptoms of the disease. This is a high-profile example of a rebound. The president's chief medical advisor also experienced it. This condition has been reported in a small number of people who have received the drug.

Scientific American talked to infectious disease experts about what the phenomenon is, how common it is, and what people should do if they get it.

Paxlovid is a question.

Paxlovid is an oral, three- pill regimen. People who catch COVID are prescribed the drug by Pfizer. Unvaccinated elderly or people with other medical conditions can be included. Two of the three pills are used to treat the COVID-causing viruses. ritonavir is a drug that helps treat HIV/AIDS by slowing its breakdown in the body.

The head of infectious diseases and global public health at the University of California, San Diego says everything they have done for COVID came out of the HIV template. He says that includes the development of vaccines, the development of treatments, and the testing.

Paxlovid was found to reduce severe disease. The group that received the drug cut COVID hospitalizations and deaths by 89 percent.

The Biden-Harris administration rolled out a Test to Treat program so that anyone can be tested for COVID and receive Paxlovid in one trip to a pharmacy or treatment center.

Paxlovid rebound is a question.

Paxlovid rebound is when a patient who received a full five-day course of treatment relapsed or tested positive after a previous negative test. Smith says that when you rebound, you can have both the symptoms and the virus at the same time. When there is a reemergence of measurable amounts of virus, it is called a rebound.

After finishing the Paxlovid course, between 1 and 2 percent of people who received the drug tested positive for COVID. The rebound experienced by people with placebo was the same as the rebound experienced by people with placebo.

Amy Barczak is an infectious disease doctor at Massachusetts General Hospital. Asymptomatic Paxlovid rebound is the result of a positive test and no symptoms. Biden was found to have the latter because he was constantly testing.

A complicating factor for an infectious disease specialist is differentiating between a true rebound of symptoms and a very slow improvement in symptoms after starting Paxlovid. This is important because it can change how people decide to stay together. To accurately say how many people experience Paxlovid rebound, you need to identify the differences.

Smith says it's important to remember that if your patient needs it, the drug will work. The trials showed that this was a drug that could keep people out of the hospital. Don't be afraid of the rebound.

Which people are experiencing Paxlovid rebound?

Shah says that being of an elderly age and having other risk factors puts you at a higher risk of rebound. The risk factors are the same for these.

It is difficult to know how often Paxlovid rebound occurs because it needs to be defined. If rebound is sometimes classified as a reoccurrence of symptoms and other times as having multiple negative tests followed by multiple positive tests, this could affect the percentage of people thought to be experiencing the phenomenon. She still believes that the rebound associated with reemergence of the virus is higher than what was reported in the original Pfizer trials. She says that between 2 and 10 percent of people take Paxlovid. I think it's somewhere in that range.

Shah found that about 1 percent of Paxlovid users rebounded, which is in line with the Pfizer trial. He thinks the rate may be as high as 5 to 10 percent, based on discussions with patients and other physicians.

Shah says that it's hard to know how many people are having a rebound because there are three tests that need to be taken. It is difficult to do prospectively because patients may not know they have rebounded so are not testing themselves for COVID or they may not tell anyone they have rebounded.

Doctors and researchers have begun to enroll Paxlovid users in studies of rebound. She says it takes a while to enroll people in these studies. Scientists will have a better idea of how many people experience it once those studies are published.

If you have Paxlovid, what should you do?

Shah emphasizes that the good thing is even if you have a rebound. You don't need additional COVID therapies, you don't need hospitalization, and you don't experience high mortality.

It is important to separate after a rebound. A subset of individuals with rebound symptoms after Paxlovid are likely to be newly infectious. She and her team took samples from seven people with rebound symptoms and were able to culture a Viruses from three of them. People need to be aware that they may be infectious despite the small sample size. Think about protecting the people around you if your symptoms return.

It's important to tell your doctor that you're experiencing symptoms of Covid again. Smith says that people who are in certain types of cancer treatment need to talk to their doctor. Smith treats these people with a second course of Paxlovid, just like Fauci did. He tells them not to go around and spread it. Some experts don't think a second course of Paxlovid is necessary.

Paxlovid has a rebound.

Some patients may experience a rebound because they aren't getting enough Paxlovid. ritonavir is part of the treatment regime because it needs to be increased in the body. The rebound was not the result of the virus becoming resistant to the drug, according to Smith. Paxlovid can make food taste bad so he thinks people will skip a dose. The majority of people who don't experience the right rate of drug release may be part of the rebound group. If you experience a lower dose, there is a chance that pockets of the virus will survive the treatment and re-emerging days later. Smith thinks that research needs to focus on the idea that some patients may not be exposed to the correct dose of Paxlovid.

All the doctors Scientific American spoke with said that they will continue to prescribe Paxlovid to their patients who need it. Barczak claims Paxlovid can still be used effectively. We can protect each other by isolating when rebound happens.