For more than a week, KTLA’s Eric Spillman has been sick with COVID-19.

He was prescribed Paxlovid, the antiviral pill approved for treating coronavirus infections. For several days after finishing the pills, he did feel better. But then came what is being call the Paxlovid rebound.

His symptoms returned and he took another Covid test.

“I knew it was going to be positive, cause I had the symptoms, and I had heard about the paxlovid rebound,” Spillman said. “I was under the impression it was a relatively unusual occurrence, but I’m hearing from a lot of people that they’ve either gotten the rebound or know someone who has.”

The Centers for Disease Control and Prevention has issued an official health advisory, saying Paxlovid is still recommended, but warning Covid symptoms can come back.

Dr. Bud Lawrence is the medical director at Henry Mayo Newhall Hospital’s emergency department. He and other doctors say the Paxlovid rebound is “definitely a real thing.”

The antiviral medication has proven very effective, but data from Pfizer — the maker of Paxlovid — now shows the rebound is happening in about 10% of patients.

“It is something that is occuring with some patients,” Lawrence said. “They take the Paxlovid and anywhere from 10 to 14 days from the initial onset of symptoms, they get another bump in symptoms.”

President Biden is on day five of his Paxlovid treatment. His doctor says the 79-year-old has nasal congestion and a bit of a hoarseness in his voice, but said the president’s pulse, blood pressure, respiratory rate and temperature are all normal.

Medical experts say the president is proof that for most patients, Paxlovid is working for its primary purpose: preventing serious illness in the elderly and immunocompromised.

“Clearly the risk-benefit ratio favors taking the Paxlovid if it’s given to the right population, then yes, it is absolutely indicative, and yes, I would advocate using Paxlovid,” said Dr. Gary Bluestone, chief of infectious diseases at Kaiser Permanente in Baldwin Park.

Despite concerns about the Paxlovid rebound, the medication is still in high demand. The FDA has also authorized some pharmacists the ability to prescribe it.