Millions of people could already have contracted the new coronavirus Covid-19 and have no idea they had it, according to researchers at Oxford University's Evolutionary Ecology of Infectious Disease group.
The scientists say the disease may have been in the UK since the middle of January, meaning many of us caught it without knowing what it was -either experiencing no symptoms or just mild symptoms that we didn't recognise.
The study, which has yet to be peer-reviewed, says the disease could have been spreading for weeks before the alert went out at the end of February,
The key symptoms of Covid-19 are a new, dry, persistent cough and a fever - feeling hot on your head, chest or back or registering over 37.7C on a thermometer.
If you have these symptoms you should check your countries website for help.
Everyone should now be in lockdown, not leaving the house for