The first reports of swine flu indicated that it would respond to common antiviral drugs like Tamiflu. But recent laboratory tests, including some by the National Microbiology Laboratory, show that Tamiflu is not effective against the H1N1 virus that causes the common flu, the Ottawa Citizen reports today. This raises a troubling question: if Tamiflu didn’t work against the common Type A/H1N1 flu virus, will it be an effective against the new H1N1 virus that causes the Mexican variant of swine flu? Other experts note that swine flu is new enough it likely hasn’t mutated into a drug-resistant bug yet; the greatest danger is overuse of antivirals to the point swine flu does develop resistance, says two experts quoted in the story. Bottom line: this is one more level of uncertainty about an illness shrouded in mystery.