People infected with SARS-CoV-2 do not show symptoms for an average of five days, according to a new estimate.

However, in rare instances, people will develop the fever, cough and pneumonia, which are the hallmark of COVID-19, only after 14 days, shows US research in the Annals of Internal Medicine.

But that shouldn’t affect the recommendation that people be quarantined or self-quarantine for 14 days, says chief author Dr Justin Lessler of the Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland.

That’s because most people don’t start their quarantine until a day or so after they realise they might be exposed.