Most of the public interest and media attention around influenza this year is on the H1N1 virus, or swine flu, and the development of a vaccine to prevent it. But the increased emphasis on flu, in general, is also having implications for seasonal influenza vaccine demand.

The start of the season when health care providers begin administering the influenza vaccine kicked off in August, and with so many uncertainties surrounding influenza this year - from the strength of swine and seasonal flu strains to the availability of an H1N1 vaccine - it is impossible to predict how the coming months will unfold.

It remains unclear whether the public will pursue the seasonal flu shot more aggressively this year, given the health scare over swine flu, or will be less inclined to get one, opting to wait to get inoculated with the H1N1 vaccine when it becomes available instead.

Nonetheless, early indicators show seasonal flu vaccinations are on the rise early in the season, which suggests patients and physicians are heeding calls from public health officials to vaccinate against both the seasonal and H1N1 viruses.

Early Indicators: Flu Vaccinations Up 237 Percent

The number of flu vaccinations administered in the four weeks from Aug. 2 through Aug. 29 was up 237 percent compared to the same four-week period a year earlier, according to data from SDI, a health care market research firm that consolidates electronic health care claims data.

The data show there were 477,000 seasonal flu vaccinations administered through Aug. 29. The majority of the inoculations had been given to children and more than half, or approximately 246,000, were MedImmune's FluMist.

"The numbers are just astonishing," SDI's vice president of clinical accounts, Laurel Edelman, said in an interview.

"The primary driver for why people get an influenza vaccine is a recommendation from their health care provider," she said, pointing out that the data suggest health care providers are vaccinating patients against seasonal flu early, perhaps to clear the decks ahead of a potential onslaught from patients seeking the pandemic vaccine later in the year.

In addition, the market research firm noted that the availability of the vaccine in August 2008 was similar to this year, so it is fair to make data comparisons.

Seasonal Flu Threat Remains, CDC Warns

During a Sept. 11 press conference, CDC officials reiterated recommendations for the public to get a seasonal flu vaccine early and follow up with the H1N1 vaccine later in the year when it becomes available in mid-October. H1N1 vaccines from Novartis, Sanofi-Pasteur, CSL and MedImmune received simultaneous approvals from FDA on Sept. 15 (see ¹ Also see "H1N1 Vaccines Get Green Light In U.S., But Is Anything Else Needed?" - Pink Sheet, 21 September, 2009.).

Both the seasonal and H1N1 strains are circulating this season, officials said, and each appears to have more serious health affects in different patient populations. Seasonal flu has more serious implications for elderly patients, while the H1N1 strain has turned out to be harder-hitting in younger populations. Despite media attention over swine flu, seasonal flu is responsible for about 200,000 hospitalizations and 36,000 related deaths each year, according to CDC.

CDC estimates that 114 to 115 million doses of the seasonal influenza vaccine will be available in the U.S. for the 2009/2010 season. Production for the vaccines was well under way when the H1N1 pandemic threat emerged last spring. Seasonal influenza vaccines include AtraZeneca/ MedImmune's FluMist , Sanofi-Aventis' Fluzone , GlaxoSmithKline's Fluarix and Novartis' Fluvirin .

Not surprisingly, another market research firm, Datamonitor, is projecting an increase in seasonal influenza vaccinations. In the U.S., vaccinations are expected to jump between 15 percent and 20 percent for the 2009/2010 flu season, analyst Hedwig Kresse predicted, noting the biggest jumps are expected in pregnant women, health care providers and children.

Seasonal Up-Tick May Be Short-Lived

Yet the upswing in seasonal flu vaccinations could slow down later in the year once an H1N1 vaccine hits the market. SDI expects the upward trend seen in the early weeks to continue until mid-October.

"The concern is that, with the pandemic vaccine coming out in October, physicians and patients will switch to just the pandemic vaccine, and that is when we could see a drop in seasonal flu vaccinations," Edelman said.

"We think we'll see a temporary boost in seasonal uptake for this season and the next. Then, it will drop again once the pandemic threat is over," Kresse predicted.

Manufacturers, Retailers Gear Up For Big Season

Beyond the media hype, promotional initiatives by vaccine makers and retailers also may be encouraging patients to get the seasonal flu vaccine early this year.

For example, MedImmune began shipping its FluMist nasal spray at the end of July to facilitate early inoculation.

In addition, while it already had promotional campaigns like its "Don't Play with the Flu" awareness campaign featuring soccer stars Mia Hamm and Brandi Chastain planned in the spring, it accelerated promotional activities once the H1N1 threat emerged.

"We've seen significant uptake of the seasonal flu so far this year," MedImmune said. "We're hoping people are heeding the public health message to get the seasonal flu vaccine early."

An analysis by MedImmune showed that starting influenza vaccination in August instead of October could help reach an additional 11.5 million children at already-scheduled health care provider visits.

With the slogan, "Don't Risk It. Get A Flu Shot," the drug retailer CVS is also promoting the availability of the vaccines. Starting Sept. 1, the company has been administering seasonal flu shots without an appointment at more than 500 MinuteClinic locations inside stores.

- Jessica Merrill ( ² j.merrill@elsevier.com )

Amid Swine Flu Hype, Seasonal Flu Vaccinations Are Off To Swift Start

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