The novel H1N1 flu virus already has hospitalized about the same number of Americans that the seasonal flu, which has yet to hit the United States in earnest, does in a typical year.
The latest midrange estimate for H1N1 cases extending from April to mid-November is about 47 million - 15 percent of the population, the Centers for Disease Control and Protection reported Thursday. About 200,000 people have been hospitalized, and among them there have been nearly 10,000 deaths.
"More than 200,000 hospitalizations ... is about the same number that there is in a usual flu season for the entire year," CDC Director Thomas Frieden said at a news conference Thursday.
And the seasonal flu itself is still to come, meaning the number of flu deaths and hospitalizations hasn't come close to its final figure.
"Until recently, we have seen very little seasonal flu. We're beginning to see influenza B as I have mentioned in the past. We did have a death in a child from influenza B. That is covered by the seasonal flu vaccine," Dr. Frieden said.
The CDC chief cautioned that although the H1N1 pandemic has receded, another H1N1 wave could occur if vaccination rates slack off.
"The more people who are vaccinated, the more people who will be protected from influenza, the fewer cases we'll have in the future, the less likely we will be to have a third wave, or more cases in the weeks and months to come," he said.
One consistent difference between the seasonal or regular flu and novel H1N1 is the unusually high number of deaths among children and those younger than 65 affected: 1,100 children and 7,500 adults 18 to 64 years have died to date from novel H1N1.
Seasonal flu normally affects people age 65 older, with 60 percent of the hospitalizations and 90 percent of the deaths occurring in this age group. In a typical U.S. flu season, about 36,000 people die.
The CDC also this week released figures showing that the aboriginal populations of Australia, Canada and New Zealand have had a three to eight times higher rate of hospitalization and death associated with the H1N1 flu. In the 12 U.S. states where half the American Indians and Alaska Natives reside, the death rate was four times higher for this ethnic group.
"The overall [American Indian and Alaska Native] H1N1-related death rate was 3.7 per 100,000 population, compared with 0.9 per 100,000 for all other racial/ethnic populations combined," the CDC reported in its Morbidity and Mortality Weekly Report.
The reasons for this are under debate, said Dr. Frieden, although they are "most likely a reflection of environmental factors and underlying conditions like diabetes and asthma that are more common, access to health care, rather than genetic or race ethnicity difference." The number of people in these groups who have been vaccinated is unknown "because a sample size is difficult to get."
Asked how receptive Americans have been to the H1N1 vaccine, he said that half of those polled "wants to and plans to be vaccinated." As of this week, 85 million doses of vaccine are available, he noted, with more providers giving the vaccine in increasing numbers to the high priority groups.
He plans to be vaccinated soon with the nasal spray version, he volunteered, because "I only got another year to get the nasal vaccine." CDC guidelines recommend the nasal spray for healthy people ages 2 to 49 who are not pregnant.
A survey from the RAND Corporation published Wednesday noted that adults began getting seasonal flu protection earlier this year than in the past two years that the institution has conducted such a survey.
It is a midseason report only, RAND economist Katherine Harris, the lead author, told The Washington Times. A final one is done at season's end.
She said this "probably" was because of advice from the CDC, which urged providers to order vaccine early and give it at once.
However, the study also found that while vaccination rates were much higher in September than the same month in 2008, by mid-November, the early spike in vaccinations had worn down and were now about the same for both years. The study showed that 32 percent of adults had vaccinated for seasonal flu by mid-November, compared with 30 percent by then in 2008.
"Given all the attention, we thought the uptake would be higher. We were really interested to see if all the attention [to flu] would increase vaccination rates. We see that it did for a limited period," she said.