People infected with coronavirus are most likely to be highly infectious in the first week after symptoms appear, research has found.
Genetic material of Sars-CoV-2, the virus that causes Covid-19, may still be detected in respiratory or stool samples for several weeks after infection.
However, no live virus was found in any type of sample collected beyond nine days of symptoms starting, the study found.
Researchers said people with the virus are mostly likely to be highly infectious for five days after symptom onset.
The review published in The Lancet Microbe suggested people infected with Sars-CoV-2 are most likely to be highly infectious in the first week after symptom onset.
The study specifically looked at people infected with Covid-19 and mainly those who were admitted to hospital.
Researchers said the results are only relevant for the period of self-isolation for people with confirmed Covid-19, and do not apply to people simply quarantining after contact.
Many countries recommend that people with the virus should self-isolate for 10 days, which the authors said is in line with their findings.
Understanding when patients are most likely to be infectious is important for informing effective public health measures to control the spread of the virus, they said.
