FRIDAY, March 17, 2006 (HealthDay News) -- The mere threat of bird flu might have frightened the American public more than the regular human flu did this season.
In the March 17 issue of Morbidity and Mortality Weekly Report, public health officials in New York City report a spike in sales of antiviral drugs in October 2005, seven weeks before any laboratory evidence of human flu activity actually surfaced.
"There was a spike in antiviral prescriptions that preceded positive laboratory evidence of flu," confirmed Claire Pospisil, a spokeswoman for the New York State Department of Health in Albany. "Laboratory evidence of flu activity in New York City really started to pick up in December 2005."
The spike did, however, coincide with a media frenzy on avian flu, suggesting that people were creating personal stockpiles of antivirals to guard against that possibility.
"Our analysis cannot prove why the prescription spike occurred, [but] it suggests that concern about avian influenza may have been a factor," Pospisil acknowledged.
In contrast to the frenetic activity in antiviral drug sales, experts say this year's human flu season appears to be relatively mild.
So far, numbers from the U.S. Centers for Disease Control and Prevention confirm that perception.
From Oct. 2, 2005, to March 4, 2006, there were 9,143 cases of the flu reported in the United States. During the 2004-2005 flu season, 23,549 flu cases were reported. In terms of number of states affected, all 50 have reported flu activity this season, while 42 states reported flu activity during the 2004-2005 season.
"The sale of antivirals is due to a fear of bird flu, not the yearly flu season," said Dr. Marc Siegel, author of Bird Flu: Everything You Need to Know About the Next Pandemic and a clinical associate professor of medicine at New York University School of Medicine in New York City. "Flu season itself got eclipsed by the bird flu."
"It was a fairly bad season on the West Coast, but mild in the East so far," he continued. "It was also a late season, late migrating across the country. It's going to be labeled a mild season overall unless we're still in it."
Even if the flu season had heated up, antivirals might not have been much help.
Four antiviral medications -- oseltamivir (brand named Tamiflu), zanamivir, rimantadine and amantadine -- are approved for the treatment and/or prevention of influenza.
Amantadine and rimantadine are included in the national stockpile to guard against a possible influenza pandemic. Unfortunately, this year's circulating flu virus has developed high levels of resistance to these two drugs, which prompted the CDC in January to advise against using them for the remainder of the 2005-06 flu season. The CDC alert was issued because more than 90 percent of samples tested were resistant to the two drugs.
In other words, both medicines are basically useless.
For the MMWR report, the New York State Department of Health monitored sales of antiviral influenza medications paid for by Medicaid while its counterpart, the New York City Department of Health and Mental Hygiene, monitored sales by a retail pharmacy chain.
In the past, peaks in sales of anti-influenza medication have coincided with peaks in the percentage of specimens testing positive for influenza.
But this year, the spike that occurred Oct. 23-29, 2005, happened seven weeks before the first World Health Organization laboratory evidence of flu virus circulation (Dec. 11-17 2005). There were no other markers of flu activity, such as nursing home outbreaks or emergency room visits, during October.
In 2004, a smaller spike in antiviral sales took place one week before any laboratory evidence of circulating virus. This coincided with media reports of expected shortages in vaccine supply.
Such personal stockpiling carries its own risks. It means that fewer drugs are available for those who actually need them, and the practice could foster more resistance.
"Inappropriate use of antiviral medications may promote the development of viral resistance," Pospisil said. She added that it is unlikely that the short-term prescribing seen this year would have led to resistance.
Siegel reserved his criticism for the media and for public health officials, stressing that a pandemic stemming from avian flu is not inevitable.
"There's way too much speculation," he said. "We need a new language to communicate risk. Public health officials haven't done a great job of distinguishing that a focus on influenza is different from alarming people."
For now, he added, "there's still a species barrier in place between birds and people, and not enough good explanations about what mutations would be needed. There seems to be a rampant assumption that if this mutation occurs, that automatically signals the end of time. H5N1 is a bad virus in birds, and well worth our attention. Talking about the worst-case scenario could be good in raising awareness, but bad about causing panic."
For more on influenza, visit the U.S. Centers for Disease Control and Prevention.