The H1N1 virus, better known as swine flu, continues to infect people across the globe, but there is a growing sense among public health officials that the newly evolved influenza strain is mild, at least for now.
Though there is still much to be learned about the strain, Richard Besser, acting director of the Centers for Disease Control and Prevention, says he sees encouraging signs that it is a mild form.
In the U.S., the hospitalization rate is only 0.7 percent, says Jon Andrus of the Pan American Health Organization: “That’s comparable to most seasonal influenza.”
That appears to be the case in New York, which, with 73, has the highest number of confirmed cases in the nation.
“We have looked daily at every hospital and every intensive care unit in the city,” says Thomas Frieden, New York City Health Department commissioner, “and we have yet to find a single patient with severe illness from H1N1.”
But that could change quickly at any moment, Andrus warns. “Influenza viruses are predictable in their unpredictability.”
Officials worldwide are watching carefully to see how the virus evolves during the winter flu season in the Southern Hemisphere, which begins in June.
“That will tell us a lot about whether the virus is changing, whether it’s becoming more severe and what measures we might want to take in the fall,” Besser says.
The World Health Organization’s figures for Monday were 1,025 cases with 26 deaths in 20 countries, says WHO flu director Keiji Fukuda. The majority of cases continue to be reported in Mexico, the U.S. and Canada, Fukuda says, and most cases in the other 17 countries are related to travel from those three countries.
That means that raising the world pandemic phase to 6 is unlikely anytime soon, he says. WHO raised the alert level to Phase 4 on April 27 and to Phase 5 on April 29. Phase 6 would indicate “a global pandemic is under way,” according to WHO.
Besser suspects that the level probably will be raised to Phase 6 at some point “given that flu viruses spread easily from person to person,” but he says that wouldn’t change the work CDC already is doing.
In the U.S., the CDC’s report for Monday was 279 cases in 36 states and one death: a toddler visiting Texas from Mexico.
As of Monday, more than 330,000 children were out of school in the U.S. because of closures as the result of actual or suspected cases of H1N1. Taken together, the students would make up the nation’s sixth-largest school district, the U.S. Education Department says.
The CDC is considering revising its original advice that schools with active cases of H1N1 close for up to two weeks, Besser says. That’s because most schools have clusters of the flu, he says, and that means the virus is “already pretty well-established in those communities,” so closing schools won’t stop its spread.