From the Guidelines
People with COVID-19 are typically contagious for 8-10 days after symptom onset, but this can vary depending on the severity of the illness and individual factors [ 1 ]. As a precaution, it's recommended to isolate for at least 10 days after symptoms start, or until 24 hours after fever has resolved without the use of fever-reducing medications like acetaminophen or ibuprofen, whichever is longer.
Key Considerations
- In severe cases, individuals may be contagious for up to 20 days [ 1 ].
- The duration of contagiousness can be longer in severely ill or immunocompromised patients [ 1 ].
- PCR positivity does not correlate with secretion of live virus, so it is of little or no value in assessing the risk of infectivity in the 3 months after confirmed SARS-CoV-2 infection [ 1 ].
- Repeated samples may improve yield in patients with a high pretest probability of COVID-19 and a negative nasopharyngeal swab [ 1 ].
Isolation Recommendations
- Patients should self-isolate for 10 days with mild to moderate disease, or 15-20 days with severe illness [ 1 ].
- After hospital discharge, 4 weeks of further isolation with regular health monitoring should be considered for COVID-19 patients [ 1 ].
From the Research
Duration of Contagiousness for COVID-19
The duration of contagiousness for COVID-19 varies depending on the severity of the illness and the individual's immune status.
- For individuals with mild-to-moderate illness, the duration of contagiousness is generally considered to be up to 10 days after symptom onset 2, 3, 4.
- For individuals with severe or critical illness, the duration of contagiousness may be longer, up to 15 days after symptom onset 2, 5.
- For immunocompromised individuals, the duration of contagiousness may also be longer, up to 20 days after symptom onset 2, 5.
Factors Influencing Contagiousness
Several factors can influence the duration of contagiousness, including:
- Viral load: The amount of virus present in the individual's respiratory secretions 4.
- Symptom severity: Individuals with more severe symptoms may be contagious for a longer period 2, 5.
- Immune status: Immunocompromised individuals may be contagious for a longer period 2, 5.
- Diagnostic testing: The presence of viral RNA or antigens in diagnostic tests does not necessarily indicate infectiousness 6, 3.
Predictors of Infectiousness
Certain predictors can indicate whether an individual is still infectious, including: