When is a person with COVID-19 (Coronavirus Disease 2019) no longer considered contagious?

When You Are No Longer Contagious with COVID-19

A person with COVID-19 is generally no longer contagious after 10 days from symptom onset, along with fever resolution for 24 hours without antipyretics and improvement in other symptoms. 1

General Guidelines for Ending Isolation

The duration of contagiousness varies based on several factors:

For Most People (Mild to Moderate Illness):

• Wait at least 10 days since symptoms first appeared
• At least 24 hours with no fever without fever-reducing medication
• Other symptoms are improving

For People with Severe Illness or Immunocompromised Status:

• Longer isolation periods may be necessary
• A case-by-case approach is recommended
• May require up to 20 days of isolation 2

Factors Affecting Contagiousness Duration

Several factors influence how long someone remains contagious:

1. Symptom Status:

   • Symptomatic individuals are more likely to remain contagious longer 3
   • Resolution of symptoms (especially fever) is a key indicator

2. Immune Status:

   • Previous infection reduces likelihood of prolonged contagiousness (70% reduction) 3
   • Vaccination reduces likelihood of prolonged contagiousness (40% reduction) 3
   • Both previous infection AND vaccination provides the greatest reduction (83% reduction) 3

3. Disease Severity:

   • Severe cases may remain contagious longer than mild cases 2
   • Patients with critical illness may shed virus for up to 32 days 2

Testing to Determine End of Contagiousness

While a time-based approach is generally recommended, testing can provide additional information:

• Antigen Testing: After 5-9 days, approximately 54.3% of people still test positive on antigen tests, with decreasing positivity over time 3
• Viral Culture Studies: Most patients with mild-to-moderate illness do not have culturable virus beyond 10 days 2

Special Considerations

Immunocompromised Patients

• May shed infectious virus for up to 20 days 2
• Require individualized assessment and possibly longer isolation

Healthcare Workers

• Those caring for high-risk patients should consider extending isolation to 10 days regardless of symptom status 4
• Among healthcare workers with Omicron variant, 13.5% still had viable virus at day 10, and 8% at day 14 4

Common Pitfalls to Avoid

1. Ending isolation too early: Even after symptoms resolve, viable virus may still be present
2. Relying solely on PCR tests: PCR may remain positive long after a person is no longer contagious
3. Ignoring symptom status: Even with negative tests, persistent symptoms may indicate ongoing infectiousness
4. One-size-fits-all approach: Immunocompromised patients and those with severe disease require longer isolation

Practical Approach to Determining Non-Contagiousness

1. Count days from symptom onset (or positive test if asymptomatic)
2. Ensure fever has resolved for at least 24 hours without antipyretics
3. Confirm other symptoms are improving
4. For standard cases: End isolation after 10 days
5. For severe cases or immunocompromised: Consider extended isolation and consult with specialists

Remember that even after the isolation period ends, wearing a well-fitting mask around others for additional days can further reduce transmission risk 3.