President Joe Biden's symptoms have reportedly improved after it was revealed he tested positive for COVID-19 on Thursday.
He's been isolating and taking the Pfizer antiviral treatment Paxlovid – but there is a possibility that Biden may have a Paxlovid rebound – which can happen in people once they've recovered.
People have reported that even after taking the therapy to treat their COVID-19 and getting better, symptoms can return and they can test positive again.
"It works by interfering with the replication of the virus," said John Swartzberg, an infectious disease expert and clinical professor emeritus at the UC Berkeley School of Public Health on KCBS Radio's "Ask an Expert" with Melissa Culross on Friday.
"The virus has to replicate in enormous numbers in our cells – then comes out of our cells and infects more cells – something needs to break that cycle," he said.
While people's immune systems are ultimately able to break the cycle, Paxlovid manages to do it much faster, speeding up people's recovery.
Related
The key with the treatment is to begin taking it as soon as possible when infection occurs, so it has less of the virus to combat. Taking it later on, after five or six days, won't work as well. "It needs to be taken within the first five days and the earlier the better," said Swartzberg.
The unexpected aspect of the treatment is the rebound that sometimes occurs in patients a few days or even 10 to 12 days after finishing the Paxlovid treatment.
For those that this happens to, they take the drug and get better relatively quickly, and then a couple of days later, the symptoms return. Usually, the symptoms are milder than the first time around but they're otherwise the same.
These people will test positive for the virus and have to go back into isolation again as they are considered contagious again. "We haven't seen anybody die with this," he said. "We haven't seen hospitalizations."
It’s still unclear why this happens. One hypothesis is that the treatment works so well it doesn’t allow people's immune systems to develop as robust a response.
"But that at this point is pretty much still a guess," he said.
There is no evidence so far that suggests the virus is resistant to Paxlovid, but there are some tentative, unconfirmed reports coming out that it may not be working as well with the BA.5 subvariant.
Related
The treatment itself is "pretty well tolerated" by patients, according to Swartzberg, but some have complained that the drug leaves a bad taste in their mouths. Others suffer some gastrointestinal issues.
But for the most part, there aren't big side effects from the treatment.
For the president, there is some concern about him taking the drug while he's on an anti-coagulant for an atrial fibrillation.
"Most of the anti-coagulants present a problem when you take Paxlovid," he said. This is one of a handful of drugs that shouldn't be taken with Paxlovid, because it decreases the metabolism of certain drugs, increasing the amount of the drug in a person's bloodstream too much.
For the five days that Biden is taking Paxlovid, he's not being given his anti-coagulant.
Others may need to try a different treatment or be monitored very closely if they find themselves in a similar situation.
LISTEN on the Audacy App
Sign up and follow Audacy
Facebook | Twitter | Instagram