On the plus side, however, the resistant strains remained "fully sensitive" to treatment with another drug, Relenza (zanamivir).
Five of the resistant patients were under the age of 5 years. Only one of the patients had been treated with Tamiflu prior to viral sampling, while three had previously been vaccinated with the 2011 influenza vaccine.
The team noted that July marked the high point of resistant cases, most of which were found within a 30-mile or so radius of Australia's seventh-largest urban center, Newcastle. A handful were located in Sydney, the country's largest city.
Raising concerns about the ease of transmission, the investigators noted that some of the resistant cases involved related patients: in four households, two family members had been diagnosed with resistant H1N1. In two other cases, the patients were linked simply by having shared a short car ride.
Hurt pointed out that the resistant strain does not appear to cause more serious illness than "normal" strains, and that no one has died as a result. But he did suggest that the very real prospect that such resistant strains could spread far beyond the shores of Australia is alarming.
"Tamiflu is widely used in the U.S.A. and other parts of the world such as Japan," he noted. "If the virus spreads widely, then there is potential that patients will be treated with a drug that will have little or no benefit. The biggest impact may be in individuals, such as the elderly or immune-compromised, who have a higher risk of complications from influenza infection and most commonly benefit from early and effective antiviral treatment."
Dr. Len Horovitz, a pulmonary specialist with North Shore-LIJ/Lenox Hill Hospital in New York City, explained that, although other non-Tamiflu treatments remain effective, the advent of resistant flu strains can waste valuable time.
"Flu medications have to be given within 24 to 48 ho
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