Most people with coronavirus will recover within about a week of getting symptoms and will not need medical care.
But some people will need to be treated in hospital – including the prime minister.
Boris Johnson, who is 55, is currently being cared for in St Thomas’ hospital in London after his symptoms worsened.
He has been receiving oxygen, but has not needed a ventilator machine to help his breathing.
Which people can get sick?
Some people are at higher risk of complications.
This includes people over the age of 70, regardless of whether they have a medical condition or not, and people of any age with underlying health conditions, such as heart disease.
There are more than 1.5 million people in the UK who are at the greatest risk of needing hospital treatment if they catch coronavirus.
This includes people with cancer who have been receiving chemotherapy, and they are being asked to stay at home all of the time to shield themselves from the virus.
Coronavirus also appears to disproportionately affect men in their 50s and 60s to a certain degree, although they are not singled out as a high risk group. But it’s not that clear-cut. Correlation isn’t necessarily cause.
Why older men?
Scientists are unsure.
UK data from intensive care hospital wards shows the average patient who is critically ill is aged 60. Most are men and many have other health conditions that could put them at increased risk, such as heart problems and obesity.
Of the 647 coronavirus-related deaths registered by the Office for National Statistics in England and Wales up to the week ending 27th March, 44 were aged 45-65 – around 7% of the total.
Death rates go up with age in both men and women, but men tend to outstrip women across the ages.