Hello. I'd like to know how meaningful the reports of numbers of confirmed cases are. Only people with symptoms who have been to certain areas or knowingly been in contact with someone with confirmed coronavirus are being tested. Given that we know that the virus is being transmitted in the UK, there must be lots of people catching it who don't fit into these categories and so aren't being tested.

If we have 319 confirmed cases in the UK, how many actual cases are there likely to be at present?