Over two thirds of those who have tested positive for coronavirus have had no symptoms, according to the first nationally representative sample. The Office for National Statistics (ONS) said this figure underlines the importance of social distancing to avoid catching the virus from those who don’t even know they have it. ‘No symptoms’ Figures from the ONS showed that 79 per cent of those who had tested positive for coronavirus had reported no symptoms on the day, and that 70 per cent reported no symptoms at all in the weeks before and after being swabbed. Peter Benton, from the Office for National Statistics, said, “If 70 per cent of people are asymptomatic that means there are people who are infectious and don’t know it, and therefore continuing with social distancing is important.” The study from the ONS could not tell if these patients were infectious, but Mr Benton said, “I could be positive and not know and I don’t want to pass it on to others. “If I was asymptomatic, I may not be very infectious but I don’t want to take the chance. We don’t know for sure what’s going on but I would rather be cautious.” What does this mean for contact tracers? The ONS said that the scale of infections without symptoms could make the NHS contact tracing symptoms much more difficult to make effective. Contact tracers depend on being able to get in touch with those with the virus and the people who have come into contact with them, but if so many people are presenting as asymptomatic, it will inevitably make this process harder. Speaking to The Times, Carl Heneghan, director of the Centre for evidence-based medicine, said that if most people didn’t have symptoms, then”this could be hugely important in the test and trace strategy. The asymptomatic spread is the more significant thing about this virus.” What are contact tracers? Contact tracers are tasked with the job of getting in touch with people who have been infected with Covid-19 and all the people that the infected person has been in contact with. High risk individuals that have been in close contact with someone diagnosed with coronavirus will be asked to self isolate for 14 days and to keep an eye on any developing symptoms. Contact tracing could help lift national lockdown measures in favour of more local lockdown procedures and individual isolation. Health secretary Matt Hancock said, “This new system will help us keep this virus under control while carefully and safely lifting the lockdown nationally.” The Department for Health has said that if people don’t comply with self isolation then it “will not hesitate to introduce tougher measures, for example making visits to check they’re home or issuing fines if they are found outside the house”. Prime Minister Boris Johnson announced to parliament towards the end of May that 25,000 contact tracers would be employed and ready to track 10,000 new cases of the virus a day by 1 June.