ATLANTA - It was six months ago that scientists discovered an ominous new flu virus, touching off fears of a catastrophic global outbreak that could cause people to drop dead in the streets. Doomsday, of course, never came to pass.
Now that the initial scare over the swine flu has subsided, health officials warn we are not out of danger yet.
"We've got many, many months ahead of us where we don't know what will happen, and we need to take the best steps we can to protect ourselves," Dr. Tom Frieden, director of the Centers for Disease Control and Prevention, said last week. "Our biggest concern is that the virus could change, mutate to become more deadly."
With winter approaching, another fear is a one-two punch in which a resurgent swine flu batters young people before the vaccine is widely available, while the ordinary flu strikes the elderly. Also, emergency doctors are worried about the strain on emergency rooms and hospitals.
To date, swine flu has hospitalized hundreds of thousands of people around the world and killed at least 4,500, including at least 600 in the United States. At least 81 U.S. children have died, including many who had no underlying health problems.
The CDC was the first to identify the new flu. It was on April 15 and 17 that the agency determined nasal samples from two children in Southern California contained a swine flu virus never been seen before. It was found to contain bits of bird and human flu.
At first, the cases represented more of a scientific puzzle than a public health threat. The two children recovered, but investigators were perplexed by how they got it, because the two kids had not been in contact with each other or with pigs.
But within a week, the situation became more dramatic. Testing linked the two children and a handful of subsequent U.S. cases to hundreds of illnesses in Mexico City. Mexican authorities closed schools, museums, libraries, and theaters to stop the spread of the disease as initial reports suggested it was killing as many as one in 15 of those infected - a horrifying death rate more than three times higher than the terrible flu pandemic of 1918-19.
A series of bad and good news followed. First, the bad: It quickly became clear that the virus was spreading not only in Mexico and border regions of the United States, but around the world. As health officials had long surmised, international air travel provided a rapid path to world contagion.
What's more, studies indicated the millions of seasonal flu shots administered the previous winter offered no protection against the unusual new virus.
But then came some good news:
•While the flu vaccine was no help, the antiviral medication Tamiflu reduced the severity of illness if taken right after symptoms appeared.
•People 55 and older, who suffer and die the most from seasonal flu each year, seemed mostly to be spared by the new virus.
•Additional investigation in Mexico suggested that many people had suffered only mild illness. Those cases were not counted in initial reports, meaning the death rate was much, much lower than originally estimated.
The disease kept spreading, and eventually the World Health Organization declared the H1N1 strain the first global flu pandemic in 40 years.
"Overall, it's a fairly typical flu virus," Richard Webby, a researcher at St. Jude Children's Research Hospital in Memphis, says now.
But this story is not over yet. There are important unanswered questions.
Most health experts believe swine flu hits children and pregnant women harder than seasonal flu, but it's not clear how much harder because officials don't know exactly how many have caught the swine flu and had only mild symptoms.
A mutation of the virus in two Dutch patients last month at first seemed to indicate the bug might be getting more dangerous, but the patients recovered and no further problems were reported. Researchers are watching for more such changes.33.74831 -84.39111
It was six months ago that scientists discovered an ominous new flu virus, touching off fears of a catastrophic global outbreak that could cause people to drop dead in the streets. Doomsday, of course, never came to pass.