Paxlovid COVID Rebound: No Evidence for More Treatment, Says CDC

No evidence exists to support an additional course of treatment in patients with COVID-19 who experience a recurrence in illness after taking nirmatrelvir/ritonavir (Paxlovid), the CDC said on Tuesday.

In a Health Advisory, the agency reiterated that patient monitoring is the most appropriate treatment, and clinicians should advise patients with symptom rebound to re-isolate for at least 5 days, as well as consider being evaluated by a medical professional if their symptoms worsen. They should also wear a mask in public for a total of 10 days following rebound symptoms.

Moreover, this rebound appears to be self-limiting, with CDC reporting an improvement or resolution in illness or positive test results within a median of 3 days. The agency added that there are currently no reports of severe disease associated with this type of viral rebound.

CDC cited case reports of recurring illness 2 to 8 days later among people with a normal immune response who completed a 5-day course of nirmatrelvir/ritonavir, including those who were vaccinated and received booster shots. Not only did illness recur, but the patients tested positive for SARS-CoV-2 via RT-PCR or rapid antigen testing.

“Based on information from the case reports, COVID-19 rebound did not represent reinfection with SARS-CoV-2 or the development of resistance to Paxlovid; also, no other respiratory pathogens were identified among known cases,” the agency wrote.

They added that while possible transmission during this viral rebound has been previously described, it is “unknown” whether likelihood of transmission is different than the initial infection.

CDC added that a small number of patients in a nirmatrelvir/ritonavir clinical trial had one or more positive test results, after testing negative, post-treatment, but this finding was also observed in patients taking placebo.

The agency encouraged clinicians to report any cases of nirmatrelvir/ritonavir rebound to both Pfizer and FDA MedWatch.