No longer a pandemic, H1N1 flu still hanging on

With frantic efforts to gird for the 2009 H1N1 influenza pandemic still etched on the public mind, health officials have been gearing up earlier than usual to do battle with the 2010 flu season.

This year there is no H1N1 pandemic. It was officially declared over by the World Health Organization last month.

But H1N1 flu is still floating around, as are two seasonal strains – H3N2 and Type B – expected to be prevalent in the U.S. this autumn and winter.

All three have the potential to unleash local epidemics that can hospitalize or even kill some sufferers, and all are included in this year’s vaccine – meaning that people don’t have to get a separate H1N1 shot.

The federal Centers for Disease Control and Prevention has simplified its recommendations of who should be vaccinated to include all Americans 6 months old or older. Last year it said the seasonal vaccination should be considered “optional” for healthy people between 18 and 64 years old.

And this year, for the first time, seniors are being offered a super shot called “Fluzone High-Dose” to boost their immune systems. It is four times more potent than the normal flu shot because it contains four times the flu-fighting antigens of the standard vaccine.

The souped-up formulation for seniors has the approval of the federal Food and Drug Administration, which is monitoring it closely this season to determine its efficacy.

The CDC in its vaccination guidelines has left the option open for seniors to try it or not without making a recommendation either way.

The high-dose formula has a slightly higher percentage of recipients reporting minor side effects, including soreness in the area of the injection and getting a slight fever that is gone within 24 hours, says William Schaffner, a Vanderbilt University specialist in preventive medicine who advises the CDC on immunization.

“Because it is four times as strong, there is a little more ‘Ouch!’ that comes with the high-dose formula with a few recipients,” Schaffner says.

Federal officials say in general, this year’s vaccine is so plentiful that everybody who wants it should be able to get it in a timely manner.

Vaccine manufacturers have geared up to produce between 160 million and 165 million seasonal flu vaccine doses and began delivering them in August.

A year ago last April, H1N1 dramatically appeared on the global stage as the first worldwide pandemic flu in 40 years – a serious threat, because pandemic flu is particularly lethal to children and young adults.

Researchers developed a separate vaccine for H1N1, which meant people needed both that and a vaccination for seasonal flu.

Because of production problems, supplies of the H1N1 vaccine were limited last October and November, just as the virus peaked, causing a noisy public clamor for the shots.

Many people, including some health care workers, refused to take the H1N1 vaccine, claiming it was an experimental vaccine rushed into production without adequate testing for safety and possible adverse side effects.

A total of 125.5 million H1N1 doses were administered between August 2009 and January, Shaffner says, and “it behaved exactly as the way seasonal vaccine behaves, a consummately safe vaccine.”

With that track record, designers of this year’s seasonal vaccine thought even those who refused the H1N1 vaccine last year would accept it this year, and included it as one of the seasonal vaccine’s three targeted viruses.

For seasonal flu, every year health authorities make an educated guess to formulate a “cocktail” vaccine to fight off the three flu strains they believe pose the biggest risk to sickening large numbers of people.

The flu season strikes first in Southern Hemisphere nations – peaking in May, June and July – offering early insight into whether our seasonal vaccine is accurately formulated before the flu moves north and peaks in November, December and January.

Some years the formulation goes after the wrong flu strains. The vaccine formulation for this year seems to be accurate, judging from what happened in the Southern Hemisphere last summer, Schaffner says.

The first confirmed flu case of this season in northeastern Washington, reported Friday, was a Stevens County resident with influenza A.

For those who were vaccinated for H1N1 last year, being revaccinated for it this year will cause no harm, according to CDC guidelines.