When is a patient taking Paxlovid (nirmatrelvir and ritonavir) for COVID-19 considered non-contagious? | Rounds When is a patient taking Paxlovid (nirmatrelvir and ritonavir) for COVID-19 considered non-contagious? | Rounds
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When is a patient taking Paxlovid (nirmatrelvir and ritonavir) for COVID-19 considered non-contagious?

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Last updated: May 24, 2026 · View editorial policy

Noncontagiousness During Paxlovid Treatment

A patient with COVID-19 is considered unlikely to be contagious once symptoms are improving overall and there has been no fever for at least 24 hours without fever-reducing medication. [1]
CDC guidance defines the ability to resume normal activities after these symptom- and fever-based criteria are met, with additional precautions for a short period afterward. [1]

Symptom and Fever Criteria

Noncontagiousness is supported when both criteria are met:

  • Symptoms are improving overall. [1]
  • No fever has occurred for at least 24 hours without the use of fever-reducing medication. [1]

Additional Precautions After Returning to Normal Activities

After meeting the symptom and fever criteria, added precautions are recommended for the next 5 days, such as improved air, hygiene measures, physical distancing, well-fitted masking, or testing when being around others. [1]

Paxlovid Rebound Considerations

If COVID-19 symptoms return after Paxlovid (“rebound”), re-isolation and renewed precautions are recommended until the same symptom- and fever-based criteria are met again for ending precautions. [2]

Test-Based De-Contagion Criteria (When Used)

Test-based strategies may be used in some circumstances, including when being around others indoors with higher risk; CDC describes criteria in its testing-based option using negative tests in sequence and at least 24 hours apart. [3]

Clinical Note on “Contagiousness”

CDC guidance does not define an absolute moment when transmission is impossible, and residual risk remains even after symptom improvement and fever resolution. [1]

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