Swine flu past prime, officials say

In April 2009 an announcement from the World Health Organization managed to scare people around the globe.

A novel and virulent strain of the H1N1 virus had been detected in Mexico, one with genetic components of an H1N1 virus that killed up to 100 million people worldwide in 1918.

What became known as the swine flu pandemic was born.

Forty Las Vegans died from the virus.

And then last week WHO Director-General Marget Chan said, in effect, that the pandemic itself had died.

"We are now moving into the post-pandemic period," Chan said.

That doesn't mean you still can't die or become terribly ill from H1N1 in Las Vegas, cautioned Dr. John Middaugh of the Southern Nevada Health District.

What it means is that out-of-season outbreaks by the virus are no longer being reported.

Now, Middaugh said, H1N1 has become what might be termed a regular circulating flu virus.

This year's seasonal flu shot, which could be offered as early as this month, will include a vaccine against H1N1 and two other flu strains, H3N2 and Influenza B.

The Centers for Disease Control and Prevention has suggested that everyone six months and older receive the new seasonal flu shot.

"The good news is that H1N1 never mutated, as we were afraid it would," Middaugh said. "The vaccine we have against it is a perfect match. So much of what happened with this H1N1 virus was a surprise."

It was a surprise, Middaugh said, that the virus was nowhere near as virulent as scientists first feared.

In fact, the CDC estimates the H1N1 virus, which basically elbowed seasonal flu viruses out of the way in the past year, was responsible for about 13,000 deaths in the United States, far below the usual estimated 35,000 deaths a year from the seasonal flu. The 40 deaths in Las Vegas from H1N1 was actually down from the usual 80 to 100 a year from seasonal flu.

Also surprising was who suffered the most from this flu strain: often the middle aged and young.

Generally, the elderly are hit hardest by the flu, but of the 40 who died from H1N1 in Las Vegas, only four were 64 years of age or older. There were 400 hospitalizations in Southern Nevada, 458 statewide, and less than 10 percent involved seniors.

Middaugh said scientists theorized that people got exposed 30 to 40 years ago to a circulating virus similar to H1N1 and they received immunity from past exposure. People younger than 60 had no pre-existing immunity.