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Coronavirus symptoms develop by day five on average, finds study

People infected with coronavirus (Covid-19) will commonly develop symptoms five days after being infected, researchers have found.

A new study reported in the Annals of Internal Medicine, examining cases from China and around the world, found Covid-19 disease has a median incubation period of 5.1 days, similar to SARS.

Examining 181 confirmed cases, reported between 4 January and 24 February 2020, the researchers found 95% of people who develop symptoms do so at or around day 5. Patients displaying symptoms such as a cough and a fever, are thought to be at the most contagious period of the infection.

The results of the study support Public Health England’s advice on a quarantine length of two weeks for individuals exposed to coronavirus.

Some spread of the infection may occur before symptoms show, but this is not thought to be the main way in which the virus spreads. The study suggests that 1% of people infected with coronavirus will develop symptoms after 14 days.

More work is needed to understand the number of people exposed to the virus who will not develop symptoms, the US-based researchers added.