Flu relief: Season off to more typical start

When family physician Cynthia C. Romero, MD, looks out at her office's reception area during the current flu season, she sees normalcy.

That's not what she or other physicians saw during the 2009-10 flu season. It started earlier and hit harder, with the influenza A(H1N1) virus adding to the seasonal flu traffic. Vaccines were harder to come by. Flu is "definitely taking a slower start" this season, said Dr. Romero, president of the Medical Society of Virginia. "I would classify it as a typical, not unusual flu season."

The Centers for Disease Control and Prevention released numbers on Dec. 23, 2010, showing that the 2010-11 flu season is, indeed, much more typical than the 2009-10 season. Influenza-associated deaths and hospitalizations are down significantly from this time last season. The H1N1 pandemic is over.

Meanwhile, vaccine manufacturers have distributed a record number of flu shots, compared with the nationwide immunization shortages in 2009. This season's vaccine includes an H1N1 strain plus two seasonal flu strains. That is in contrast to 2009-10, when manufacturers hurriedly developed separate vaccines for seasonal and H1N1 flu strains, an effort that was problematic. Critics cited antiquated technology unable to keep up with high demand.

Unlike the 2009-10 flu season, this season consumers are not being besieged with advertisements exhorting them to take precautions against the flu. The Dept. of Health and Human Services is not sponsoring a contest (won last year by a rapping physician) to get the public to come up with the best H1N1 prevention ad.

However, "normal" doesn't necessarily mean "mild." The CDC is urging health professionals to remain vigilant about vaccinating patients, particularly as the nation enters the winter months, when flu cases tend to increase. The typical flu season lasts from October through April, with influenza cases peaking around February. The CDC Advisory Committee on Immunization Practices recommends that everyone 6 months and older receive the vaccine.

"The fact that most doctors aren't seeing a lot of influenza right now shouldn't be mistaken for this being a mild influenza season," said Carolyn Bridges, MD, associate director for epidemiologic science in the Influenza Division at the CDC. "The flu season is still coming, [but] there's no way for us to know how severe it is going to be."

Disparities among seasons

There were 724 flu-related hospitalizations and 16 deaths (two of them in children) between Oct. 3 and Dec. 18, 2010, that were reported to the CDC. As is typical of seasonal flu, disease prevalence has fluctuated across the country from week to week, but the South has led the nation in influenza activity in December 2010, the CDC said. Among those states is Georgia, where four flu-related deaths, all among adults, were reported to the Georgia Dept. of Community Health.

Although infectious disease specialist William Schaffner, MD, said this is a normal way for influenza to start, it marks a dramatic shift from a year earlier. More than 36,000 people were hospitalized with influenza-associated illness, and about 1,600 people died -- 221 of them children -- from Aug. 30 to Dec. 19, 2009, the CDC said.

The leading factor for this disparity is pandemic influenza, which was the primary flu strain circulating during the 2009-10 season, infectious disease experts said. Pandemic flu involves a completely new virus, which means that significantly fewer people have immunity to it, than seasonal flu strains that gradually change from one year to the next. The result of pandemic flu -- in the case of 2009-10, H1N1 -- is a surge in related illness and death that often appears earlier in the year than it would with seasonal influenza.

As of December 2010, the confirmed flu cases largely involved influenza A viruses other than H1N1, and influenza B viruses, according to the CDC. A minimal amount of H1N1 has been reported.

Dr. Bridges attributed the low H1N1 prevalence, in part, to the large number of Americans -- about 60 million -- who were infected with the disease and the millions who were vaccinated against it in 2009-10. "We're not going to see the kinds of high illness rates we saw last year because there is some immunity" to H1N1, she said.

Vaccine plentiful

Another factor contributing to the nation's more typical flu season is an ample supply of influenza vaccine. During the 2009-10 season, the nation fell millions of doses behind what HHS estimated was needed to protect Americans against the H1N1 virus. People waited for hours at community clinics, many of which reported running out of the vaccine before satisfying the demand. Many doctors didn't know when -- or if -- their offices would get the vaccine.

But for 2010-11, manufacturers already have delivered an estimated 163 million doses to central distribution points, according to the CDC. This is the most flu vaccine ever distributed in the U.S. in a season, the CDC said. Manufacturers project producing as much as 165 million doses. This season's vaccine includes a pandemic 2009 H1N1 virus, as well as an A/Perth/16/2009 (H3N2)-like virus and a B/Brisbane/60/2008-like virus.

Adding the H1N1 virus to the seasonal flu immunization probably helped get doses to the public earlier and contributed to the disease's slow start, said Dr. Schaffner, chair of the Dept. of Preventive Medicine at Vanderbilt University School of Medicine in Tennessee.

Nearly one in three people 6 months and older received the flu vaccine as of Nov. 7, 2010, according to a CDC survey of more than 46,000 people. Among those not yet immunized, 15% said they would definitely get the vaccine, and 25% reported that they would probably receive it. Immunization was higher among whites (35.8%) than for blacks (27.1%) and Hispanics (25.4%).

In a separate survey, the CDC found that 56% of health care workers reported having already been vaccinated against the flu as of mid-November 2010.

The overall vaccination rate is comparable to -- if not slightly greater than -- the rate during a similar time in 2009-10, said Anne Schuchat, MD, director of the CDC's National Center for Immunization and Respiratory Diseases.

"We're very encouraged by the number of people who have already received a flu vaccine, but many others could benefit from being vaccinated and do still need to be protected," she said in a December 2010 news briefing.

In Dr. Romero's two-physician Virginia practice, patient interest in flu vaccine has been so high that by mid-December 2010, fewer than 30 doses remained from the 1,500 she ordered. Still, she said persuading some patients to be immunized has been challenging due, in part, to the milder start of flu season compared with 2009-10.

"I try to explain it's still a serious condition, and we still need to prevent it," Dr. Romero said. "But they're not as receptive to the urgency" of vaccination as they were last season.