Flu Activity Still Rising; Likely to Continue for Weeks

With 47 states reporting "widespread geographic influenza activity" for the week ending Jan. 5 -- up from 41 the previous week -- and the nationwide pediatric death toll now at 20, the CDC is urging people who have not already been vaccinated to get a flu shot.

"Vaccination is the single most important step you can take to protect yourself," said CDC Director Thomas Frieden, M.D., M.P.H., in a Jan. 11 media briefing. "Vaccination is far from perfect, but it's by far the best tool we have to prevent influenza."

Given the 2012-13 flu season's earlier-than-normal start, and with most of the country currently affected, said Frieden, "it's likely that influenza will continue for several more weeks."

"But, as we often say, the only thing predictable about flu is that it's unpredictable. Only time will tell us how long our season will last and how moderate or how severe this season will be in the end."

This year's influenza season is following the same ebb-and-flow course seen in previous years, According to Frieden. "We are seeing a decrease in the most recent week in some areas while other parts of the country -- particularly in the west -- appear to continue to be on the upswing."

CDC medical epidemiologist Joe Bresee, M.D., who also participated in the briefing, said people who have not been vaccinated need to do so because reports of localized shortages have begun to come in to the agency.

Current CDC data indicate that more than 130 million doses of vaccine have been given already, and roughly 37 percent of Americans had been vaccinated as of mid-November. "The message is that a lot of the vaccine in the United States has been given by this time of the year by a lot of doctors' offices, so it may be that you have to call a couple places to find the vaccine … but it should be available for you," said Bresee.

"Hopefully, we'll end up much higher than 37 percent (vaccination rate) and close to 50 percent," he added. "We would like, of course, that every American gets vaccinated that's eligible for vaccination for flu."

Because of the early onset of this year's flu season, Frieden said the CDC was able to evaluate the overall effectiveness of the vaccine earlier than usual, and he gave the current vaccine an effectiveness rating of 62 percent. That's good, he said, but there is still room for significant improvement.

"About 90 percent of all of the strains circulating are included in the vaccine," he said. "In fact … the pick of vaccine strains was as good as it could have been this year. The other close to 10 percent (includes) a second influenza B, and within a year or two, we do expect manufacturers to have on the market vaccines that have space for four different vaccines, including two influenza Bs."

Bresee said novel approaches for improving vaccine efficacy, such as looking at different proteins on the surface of the vaccine or different areas of the protein on the surface of the vaccine, are showing promise.

"The goal, clearly, is to find a vaccine against influenza that you don't have to give every year -- that works better and can work for more people," he said. "I think there's hundreds of labs around the world and hundreds of field sites around the world that are actively studying this area, so, hopefully, in the next several years, we'll get those greater vaccines. In the meantime, we have better and better vaccines every year."