( CNN ) -- More than 1,100 people worldwide have died from swine flu since it emerged in Mexico and the U.S. in April , according to the latest figures from the World Health Organization . A young girl wears a mask at a hospital in Hanoi . Vietnam reported its first death from swine flu this week . As of July 31 , the total number of victims killed by the H1N1 virus , also known as swine flu , stood at 1,154 -- an increase of 338 since WHO 's previous update on July 27 . The virus has spread around the world with unprecedented speed , spreading as widely in six weeks as common influenza viruses spread in the six months , according to WHO . WHO data showed the total number of laboratory confirmed cases at 162,380 , but the number could be higher since individual cases no longer have to be tested or reported . The total number of countries and territories reporting at least one case of infection now stands at 168 , with new cases reported in Azerbaijan , Gabon , Grenada , Kazakhstan , Moldova , Monaco , Nauru , Swaziland and Suriname . In the United States , federal health officials are worried about the upcoming flu season . They say nearly 160 million Americans may need to be vaccinated against the H1N1 virus , but it wo n't be as simple as a single shot . In a background briefing with reporters on Tuesday , two senior administration officials said the vaccine , which is still in clinical trials , would require two shots . The first shot would be followed by a second shot three weeks later . Immunity to the virus would finally kick in two weeks after that . That means someone who is vaccinated by the time the program is expected to launch in late October wo n't get protection until late fall . On Tuesday , British-based pharmaceuticals giant GlaxoSmithKline announced it had signed contracts with nine governments to provide 96 million doses of a H1N1 vaccine and was in ongoing discussions with governments to provide further supplies . GlaxoSmithKline has already signed deals worth $ 250 million in total to provide 195 million doses and plans to donate 50 million doses to the World Health Organization . `` First supplies of the vaccine will be available to governments from September onwards , with shipments expected in the second half of 2009 and early 2010 , '' GlaxoSmithKline said in a statement . `` The exact pace of delivery will be dependent on capacity and the yield of the influenza strain . '' Details of the immunization program were revealed as part of the government 's overall plan to deal with what is expected to be a difficult flu season . The federal Advisory Committee on Immunization Practices last week issued sweeping guidelines for a vaccination campaign against the swine flu strain , identifying more than half the population as targets for the first round of vaccinations . The priority groups include pregnant women , health care and emergency services personnel , children , adolescents and young adults from six months to 24 years of age , household and caregiver contacts of children younger than six months and healthy adults with certain medical conditions . The symptoms of swine flu are similar to that of seasonal flu and include fever , cough , sore throat , aches and runny nose , according to the Centers for Disease Control and Prevention . A significant number of infected people have also reported diarrhea and vomiting .
WHO : Swine flu deaths up 338 in recent days to 500 in total worldwide . WHO : Virus spreads in 6 months as far as most viruses spread in 6 months . U.S. plans to vaccinate nearly 500 M Americans ahead of winter ` ` flu . '' WHO has signed deals to provide 10 million doses of vaccine this year .