to have a vaccine tomorrow . We would have wanted to have it yesterday , '' she said . `` It 's a long journey . '' She said there is `` no doubt '' that a vaccine can be made `` in a relatively short period of time . '' The steps involved in producing a vaccine involve isolating a strain of the virus , which has already been done , and tweaking it so manufacturers can make a vaccine , Kieny said . The tweaked virus will be shipped to manufacturers , who will fine-tune it . Then come more tests before national regulatory agencies decide whether to approve a vaccine . As researchers work , at least one politician at the epicenter of the outbreak expressed optimism Friday . Authorities in Mexico are `` beginning to see evidence that the -LSB- virus -RSB- might be letting up , and the number of people who have been hospitalized has leveled out in regards to people who are contagious , at least as of yesterday , '' Mexico City Mayor Marcelo Ebrard told reporters . Watch how Mexican authorities are dealing with the outbreak '' `` We do have
GENEVA , Switzerland -LRB- CNN -RRB- -- The number of confirmed swine flu cases across the globe kept rising Friday , but some signs of hope emerged in the battle against the worldwide outbreak . Tourists sunbathe wearing surgical masks in the popular Mexican resort of Acapulco . The World Health Organization said Friday that the number of confirmed cases stood at 367 worldwide , including 141 in the United States and 156 in Mexico . Thirteen countries have confirmed cases , the organization said . Meanwhile , researchers worked to develop a vaccine for swine flu , which is also known as 2009 H1N1 . The Centers for Disease Control and Prevention hopes to have a vaccine to manufacturers within a month , said Michael Shaw , lab team leader for the H1N1 response at the CDC . `` We 're doing the best we can as fast as we can , '' he said . Yet it would take four to six months from the time the appropriate strain is identified before the first doses become available , said Dr. Marie-Paule Kieny , WHO director of the Initiative for Vaccine Research . `` Of course we would like