Certain seasonal influenza A (H1N1) viruses have garnered a rare dual resistance to both adamantine and oseltamivir, the only two approved antiviral drugs on the market, according to a study published this month in The Journal of Infectious Diseases.
The study, which reviewed over 3,000 viruses across each of the last three influenza seasons from the U.S., Canada, China, Kenya, and Vietnam, concludes that a highly statistically significant increase in dual-resistance has taken place since the 2007-2008 influenza season.
While just 1 of 1,753 (0.06%) viruses tested in 2007-2008 were dual resistant, the number grew to 1.5% (21 of 1,426) in 2008-2009, and then jumped to 28% (7 of 25) in 2009-2010. Although the 2009-2010 sample is currently much smaller than the first two, the results are compellingly different. The researchers conclude that with greater resistance to drugs comes greater ability to spread.
By asking close to 30,000 randomly selected Americans each month whether or not they had a cold or the flu "yesterday," the Gallup-Healthways Well-Being Index data provide insight into the prevalence of these conditions month over month throughout the course of the season.
In 2009-2010, self-reports of daily flu were far lower than the same months in 2008-2009, as Americans made special efforts to curtail the spread of H1N1 through both public health policy and common sense means.
Thus far in the 2010-2011 season, self-reports are down still further, with just 2.1% of Americans indicating that they were sick with the flu on any given day in November, compared with 2.4% in the same month last year, and 2.7% in November 2008.
So, while flu drug resistance is apparently on the rise, those getting sick with the flu in the U.S. are, so far at least, tracking in the other direction.
Dual-resistance influenza can be serious if you are very young or very old and get sick with H1N1. For those folks, anti-viral drugs can sometimes be the difference between life and death. Same with the small percentage of people in between that get especially sick. For everyone else, anti-virals are sort of a boutique drug; if you take them you usually kick your illness a day or so sooner.
Gallup will continue to monitor reports of colds and the flu in the United States and update and publish new updates on Gallup.com.
Posted by Dan Witters