The newly pandemic coronavirus, popularly known as Covid-19, usually takes five days on average to start showing symptoms in affected people, scientists have confirmed.

The virus, which can cause fever, cough and breathing problems, is spreading around the world and has already affected more than 111,000 people.

A US research team said after their analysis that most people who develop symptoms do so on or around day five, according to a report of BBC.

Anyone who is symptom-free by day 12 is unlikely to get symptoms, but they may still be carriers, the research team added.

They researchers advised people who could be infectious -- whether they have symptoms or not -- to self-isolate for 14 days to avoid spreading it to others.

If they follow that guidance -- which has already been adopted in the UK and US -- it is estimated that for every 100 individuals quarantined for a fortnight, one of them might develop symptoms after being released, Annals of Internal Medicine reports.

Lead researcher Prof Justin Lessler, from Johns Hopkins Bloomberg School of Public Health, said the findings were the best "rapid" estimate they have to date, based on 181 cases in total.

But he said they still have much more to learn about the virus.

It is unclear how many people develop symptoms overall -- the study did not assess that.