Coronavirus Rebound After Pfizer’s Paxlovid Oral Antiviral Drug

On Tuesday, the CDC warned Americans about the potential for coronavirus recurrence after using Pfizer’s antiviral drug Paxlovid. CDC officials are not recommending any changes to the ordinary course of medication after some patients showed a revival of symptoms post-treatment.  

“There is currently no evidence that additional treatment is needed with Paxlovid or other anti-SARS-CoV-2 therapies in cases where COVID-19 rebound is suspected, independent of treatment with Paxlovid and regardless of vaccination status,” stated officials in their advisory.  

The FDA authorized Paxlovid in December of 2021 to treat mild-to-severe COVID-19. In November of the same year, the federal government purchased 10 million doses of Pfizer’s Paxlovid when clinical trials demonstrated the drug’s efficacy. The drug’s initial emergency use authorization (EUA) was for patients 12 years of age and older who had tested positive for the coronavirus. Pfizer is currently involved in Phase 2 and 3 of a clinical trial to assess the effectiveness of Paxlovid on children from ages 6 to 17.  

The FDA’s EUA for Paxlovid did not include any language concerning the possibility of symptom recurrence after the 5-day Paxlovid treatment period. 

Initial clinical trials showed that Paxlovid effectively reduced hospitalizations in patients at high risk of disease progression. Treatment of the experimental group resulted in a 6-fold decrease in hospitalizations in patients treated with the drug and a significant reduction in death.  

Pfizer’s drug is not the only antiviral available to treat COVID-19. Merck’s molnupiravar also holds an emergency use authorization; however, in trials, it was not shown to be as effective at reducing hospitalization compared to Paxlovid.  

The CDC was prompted to issue the recent warning to the public after patients with normal immune responses who completed a course of Paxlovid had recurrent illness days after treatment. Patients with recurrence did not test positive for COVID-19 during the reappearance of symptoms. The CDC advisory also mentioned that a small number of patients included in Pfizer’s original clinical trials did see similar cases of recurrence. However, there was no increase in hospitalization or death associated with the reappearance of illness.  

Pfizer has seen success with its coronavirus pharmaceuticals, including receiving expanded FDA approval for its vaccine. As of May 15, it is estimated that 343 million doses of the Pfizer BioNTech vaccine have been administered in the United States alone. 

Currently, the United States is seeing an uptick in coronavirus cases as the Omicron variant, and its subvariants continue to spread. Hospitalizations and deaths have remained low despite the increase in cases.