More countries are reporting cases of swine influenza A-H1N1, as the outbreak centered in Mexico continues to spread. The World Health Organization says the virus has been found in 15 nations.
Health officials in France, Denmark and Hong Kong reported their first confirmed cases of swine flu on Friday. Several other suspected cases were being studied. Britain also reported the first case of a person who brought the virus back from Mexico and passed it to another person in the country.
Hong Kong officials took aggressive measures to combat the flu, by placing 300 people in quarantine at the hotel where an infected man was discovered.
In Mexico, officials began a five-day shutdown, including businesses, schools and non-essential government offices. Officials hope the action will limit the possibility for more people to become infected, as health experts work to understand the virus.
One key question is why the confirmed cases outside Mexico do not include signs of serious illness. Fifteen people have been confirmed died from the virus in Mexico,but the suspected death toll there is more than 160. One death has been reported elsewhere - that of a child who traveled from Mexico to U.S. state of Texas.
In Europe, the World Health Organization says it plans to ask vaccine manufacturers to include the new strain of swine flu into future vaccines. The agency's director of vaccine research, Marie-Paule Kieny, says current vaccines include a strain of H1N1 that is completely unrelated to the current outbreak.
"For the time being, the results show there is very little chance that seasonal vaccines used in all countries would be effective against this particular virus," she said.
Kiney said she is confident an effective vaccine against the latest strain of swine flu can be ready in coming months.
Top flu expert for the U.S. Centers for Disease Control and Prevention, Nancy Cox, says it may be too late to include the new strain in vaccines for the next flu season. She says many companies have already begun producing their supply for next season. But Cox says manufacturers could make a second vaccine to provide specific protection against A-H1N1. "So that we would be able to have the seasonal vaccine, and then if necessary a supplemental vaccine with this new H1N1 virus," she said.
Cox added that experts are hopeful the new strain may not be as virulent as those in past outbreaks. She said genetic tests show it does not share the same traits as the virus that caused the 1918 flu pandemic.