Despite worries that COVID-19 symptoms can return after patients take the drug Paxlovid, such cases of rebound symptoms are actually rare, a new study shows.

In an advisory last month, the U.S. Centers for Disease Control and Prevention cautioned that COVID-19 can sometimes make a comeback after an infected person has gone through a round of the antiviral pills.

In these cases of “COVID-19 rebound,” the illness improved or resolved within an average of three days, without additional treatment, the CDC advised in May.

The U.S. Food and Drug Administration first approved Paxlovid as a COVID treatment back in December 2021.

The new study included 483 high-risk patients, median age 63, who received a five-day course of Paxlovid, comprised of the drugs nirmatrelvir and ritonavir.

Most of the patients had been vaccinated and many had received booster vaccinations. While the patients were high-risk for COVID-19, no one was immunocompromised, the Mayo Clinic researchers said.

All of the patients in the study recovered. Only four developed COVID rebound symptoms, which were generally mild. Two patients were admitted to the hospital, but for reasons other than COVID, according to the study. The results were published June 14 in the journal Clinical Infectious Diseases.

The patients with rebound symptoms included:

• A 75-year-old man with coronary artery disease who had increased cough and muscle aches 19 days after Paxlovid treatment
• A 40-year-old woman with obesity, high blood pressure and kidney disease who developed fatigue and sore throat six days after treatment
• A 69-year-old man with high blood pressure and obesity who had nasal discharge and cough 10 days after treatment
• A 70-year-old man with a history of prostate cancer, obesity, high blood pressure and high cholesterol who developed significant sinus congestion 10 days after treatment.

“We found that rebound phenomenon was uncommon in this group of patients,” said study co-author Aditya Shah, an infectious diseases physician and researcher. “The four individuals who experienced rebound [symptoms] represent only 0.8% of the group, and all of them recovered quickly without additional COVID-directed therapy.”

One possible explanation for rebound symptoms after treatment with Paxlovid is that the coronavirus may trigger a secondary immune response that causes mild COVID-19 symptoms, but further research is needed to confirm that, the researchers noted.

They added that all four patients with rebound symptoms had been vaccinated more than 90 days before contracting COVID and had preexisting health problems known to complicate COVID-19 recovery.

According to last month’s CDC advisory, “Recent case reports document that some patients with normal immune response who have completed a five-day course of Paxlovid for laboratory-confirmed infection and have recovered can experience recurrent illness two to eight days later, including patients who have been vaccinated and/or boosted.”

The agency noted that a relapse after Paxlovid treatment does not mean the antiviral does not work, and the therapy “continues to be recommended for early-stage treatment of mild-to-moderate COVID-19 among persons at high risk for progression to severe disease.”

More information

The U.S. Centers for Disease Control and Prevention has more on COVID-19 treatment.

SOURCE: Mayo Clinic, news release, June 14, 2022

Source: HealthDay