Why is the flu so resistant to Tamiflu?

The CDC recently reported that 49 of the 50 H1N1 flu viruses were resistant to Tamiflu (oseltamivir).

Infectious disease physician Paul Sax shares some theories on why this is happening, and cites a virologist who says “it might be the result of preventive programs in nursing home-type settings during flu outbreaks.”

Tamiflu is normally recommended during flu outbreaks in high-risk populations, like nursing homes or other long-term care facilities. Given the resistance, Dr. Sax recommends a trend towards zanamivir or rimantadine.

How long will it be before the virus becomes resistant to these other drugs? Will we face a future where “we’ll be using nothing but TLC, which is kind of where we were several years ago?”