( CNN ) -- The World Health Organization on Friday reported 2,500 confirmed cases of swine flu in 25 countries , with 44 deaths from the disease . A researcher investigates swine flu at the Centers for Disease Control and Prevention in Atlanta , Georgia . In the United States , the total number of confirmed cases of the H1N1 virus , as swine flu is officially called , nearly doubled to 1,639 from the day before , with reports coming from 43 states , the Centers for Disease Control and Prevention reported . The U.S. Navy said Friday that 12 crew members aboard the USS Dubuque have been diagnosed with swine flu . The amphibious transport dock ship had been due to deploy on June 1 to the South Pacific on a humanitarian mission , Cmdr . Joseph Surette , a Navy spokesman , said Tuesday . The ship was being scrubbed and disinfected , and its remaining 370 crew members were given Tamiflu as a precaution , Surette said . Navy officials said the ship could still be deployed in an emergency , but would remain in port in San Diego , California , until commanders determine the crew is suitable to deploy . Dr. Sylvie Briand , acting director of the Global Influenza Program for the World Health Organization , said the agency will remain at pandemic alert level 5 -- one step away from its highest level -- because while there are an increasing number of cases , there is no evidence of the community transmission outside North America that would push the alert to level 6 . Of the 44 deaths reported , two were in the United States and 42 in Mexico , which has the highest concentration of swine flu cases , with more than 1,100 . President Obama , speaking on the H1N1 virus during a town hall meeting for Latinos , said Americans should continue to take basic precautions such as frequently washing their hands . He also said the country should prepare for a particularly tough flu season this fall . `` The virus may not have been as virulent as we once feared , but we 're not out of the woods yet , '' Obama said . Briand of WHO said many of the new cases being reported are imported -- returning travelers bringing them into their countries -- and cases resulting from close contact with those already infected , such as family members . Meanwhile , Britain 's health secretary announced Friday that his country 's Health Protection Agency has sequenced the full genetic code of the H1N1 virus , the first step in producing a European prototype of a swine flu vaccine . `` This is critical in understanding how the virus operates and identifying the crucial parts of the virus that can be used in vaccine manufacture , '' said a statement from the agency . `` Researchers hope that European manufacturers will be able to take delivery of candidate vaccine prototypes in the coming months so preliminary steps to mass vaccine production can begin , '' the statement said .
World Health Organization reports 44 deaths in Mexico and the United States . U.S. Navy says 12 crew members aboard USS Dubuque diagnosed with virus . The CDC has reported more than 100 cases of swine flu across the country since last week.