The discovery of a H1N1 strain which is resistant to the antiviral drug oseltamivir was made in laboratory tests at Ramathibodi Hospital. Virus experts and health authorities will meet tomorrow to review the national strategy on tackling H1N1 flu in the wake of the find.
The meeting will discuss the need to reassess treatment guidelines, and stockpile the alternative antiviral drug zanamivir, said Deputy Public Health Minister Manit Nopamornbodee.
The discovery comes as the Public Health Ministry has extended its distribution of oseltamivir to clinics across the country. This will lead to the drug being prescribed more, possibly further increasing the risk of resistance growing.
Heath experts have cautioned that overuse of the antiviral drug may lead to drug resistance. Mr Manit called on the public not to panic.
"The discovery of a drug-resistant strain is common. We have told clinics to be careful when prescribing the drug," he said. Prof Dr Wasun Chantratita, chief of virology and molecular microbiology at Ramathibodi Hospital, said the drug-resistant strain was found in a Thai who had since recovered from H1N1.
He said another case of antiviral resistance had been recorded in a seasonal-flu patient. The discovery of the two cases of drug resistance was made in laboratory testing of 50 samples of confirmed type A H1N1 virus.
Of 15,000 samples sent for testing, 10,000 were confirmed as influenza and of those 80% were the A H1N1 strain. "We can say anyone who contracts influenza now can be assumed as having H1N1," he said. "Interestingly, we have never found any patient who contracts H1N1 and seasonal flu at the same time."
About 80% of seasonal flu patients are drug-resistant, so the chances of H1N1 patients being resistant were also very high.
"But prescription of the antiviral drug is needed to reduce fatalities. As long as an antiviral vaccine is not yet available, it is necessary to use the drug," he said.
Dr Thawee Chotpitiyasunont, chairman of a committee setting national health strategy on the flu pandemic, said monitoring of drug resistance must be stepped up.