(HealthDay News) — Few patients experience rebound of COVID-19 symptoms after nirmatrelvir/ritonavir (NM/R) treatment, according to research published online June 14 in Clinical Infectious Diseases.

Nischal Ranganath, M.D., Ph.D., from the Mayo Clinic in Rochester, MN, and colleagues conducted a retrospective review among patients who received NM/R treatment for mild-to-moderate severe acute respiratory syndrome coronavirus 2. Data were included for 483 patients (median age, 63 years) who had a high risk for severe disease progression. Overall, 93% of the patients were fully vaccinated.

The researchers found that four of the patients (0.8%) experienced symptom rebound, defined as recurrence of COVID-19 symptoms following successful completion of five days of NM/R therapy, at a median of nine days after NM/R treatment. All four were fully vaccinated. None of the patients required hospitalization, and all improved without further treatment.

“Rebound after NM/R treatment is uncommon in our population of high-risk, but mostly nonimmunocompromised [patients],” the authors write. “Among the patients who developed rebound of symptoms after NM/R treatment, the clinical presentation was mild and did not require COVID-19 directed therapies.”

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