Less than 1 percent of the 483 high-risk patients who took Paxlovid experienced side effects, according to research published in Clinical Infectious Diseases on June 14.
All participants from the study, which had a median age of 63, recovered from COVID-19 infection, according to Rochester, Minn.-based Mayo Clinic, whose researchers led the study.
Four fully vaccinated patients felt adverse effects from Pfizer's at-home treatment:
- A 40-year-old woman with obesity, hypertension and kidney disease acquired fatigue and sore throat six days after treatment
- A 69-year-old man with hypertension and obesity developed nasal discharge and cough 10 days after therapy
- A 70-year-old man who has a history of prostate cancer, obesity, hypertension and high cholesterol, experienced significant sinus congestion 10 days after treatment
- A 75-year-old man with coronary artery disease had increased cough and muscle aches 19 days after treatment
Two patients in the study were hospitalized "for reasons other than COVID-19," according to Mayo Clinic.
Last month, an FDA official cautioned that the antiviral treatment couldn't block recurring symptoms. Pfizer CEO Dr. Albert Bourla disagreed, arguing a symptom relapse was rare.
The CDC issued an alert May 24 warning that some Paxlovid patients were symptomatic two to eight days after testing negative.
With an 89 percent efficacy rate in diminishing symptoms, Paxlovid is currently the nation's most popular COVID-19 treatment.