GENEVA (AFP) - The swine flu virus has spread to almost every country in the world since it was discovered at the end of March, the World Health Organisation said Friday. The spread of this virus continues, if you see 160 out of 193 WHO member states now have cases, so we are nearing almost 100 percent but not quite yet, said Gregory Hartl, spokesman for the WHO. Hartl added that the A(H1N1) virus, which the WHO declared a pandemic in June, has resulted in around 800 deaths. However, he said it was not possible to give a death rate for the virus, given that we dont have the exact numerator or denominator. The WHO late last week stopped issuing figures of infected people worldwide. It said however that it was continuing to watch for the viruss appearance in new territories. Meanwhile, Hartl said there remained many unknowns about the virus. We dont know how the virus will change going forward, he said. Another unknown is how the virus would behave in the northern hemispheres winter, given that it was uncovered only during springtime in the north, he added. What the WHO has found, however, from data from Canada, Chile, Japan, Britain and the United States is that the majority of cases are occurring in younger people, with the median age reported to be 12 to 17 years, the health agency said in a statement published later Friday. As the disease expands broadly into communities, the average age of the cases is appearing to increase slightly. This may reflect the situation in many countries where the earliest cases often occurred as school outbreaks but later cases were occurring in the community, it explained. Meanwhile, at least 160 Britons are in quarantine for swine flu in China, India, Singapore and Egypt, the Foreign Office in London said Friday. The bulk of those affected 138 are in China, where 61 British schoolchildren and teachers are in quarantine in Beijing while there are 77 students and teachers in Hangzhou, said a spokeswoman. Where necessary, in a few cases, we have taken up concerns on their behalf, she said, adding that British embassies were offering consular help to those involved. Not all of those in quarantine necessarily had swine flu, the spokeswoman stressed, adding that there were also likely to be other Britons in quarantine abroad who have not come to the Foreign Offices attention. There are also likely to be other scattered cases around the world in countries like Turkey, but Fridays statistics represent most of the Britons abroad who are affected, she said. The Foreign Office said it was paying close attention to the welfare of Brits in quarantine and was keeping in touch with people in quarantine to check on their welfare and pass messages between relatives. Where we can we are also helping Brits in quarantine by arranging delivery of clothes, food, drinking water, and books/magazines to relieve the boredom, it said in a statement. Foreign Secretary David Miliband said Britain was keeping in close contact with governments around the world over swine flu. Thats something that has been coordinated for some weeks now because its important we recognise the international nature of the problem, he said. At least 30 people with swine flu have died in Britain, which has been hit harder than any other European country by the A(H1N1) virus.