Health officials confirmed nine new cases of the H1N1 flu virus in Britain today, including six children from a school that has been shut, Reuters reported. These bring the total suffering from the virus to 48. The Health Protection Agency said the six children were from a school in London that had been closed because several pupils had already contracted the illness. Three adults were also confirmed with the virus. One of the new adult cases is from the East Midlands and got it through person-to-person contact. Another is in London and developed the influenza virus while in Mexico. A third, a 19-year-old from Greenock in Scotland, has also tested positive after coming into contact with someone who had travelled to Mexico. He is being treated at Gartnavel Hospital in Glasgow for a chest infection, although his condition is not serious. "So far all infections in the UK have been mild, and cases have been diagnosed and treated early," a Department of Health spokeswoman said. "This reduces the severity of symptoms, and helps to limit the spread. But we must not be complacent -- it is right to prepare for the possibility of a global pandemic." On Thursday, the Department of Health said swine flu was still a threat to the population. The virus has killed 48 people in Mexico but all of those infected so far in Britain have had relatively mild symptoms.