Abusing Tamiflu – the ultimate anti- H5N1 weapon – will result in the drug not being effective if there is a bird flu outbreak, three leading medical experts warned yesterday.
Chinese University microbiology professor Paul Chan Kay-sheung, head of respiratory division David Hui Shu- cheong and pediatrics professor Ellis Hon Kam-lun worry that doctors may be under pressure from patients to prescribe Tamiflu unnecessarily amid widespread fear of a disease outbreak in the community.
They also warned that it was not unusual for unscrupulous pharmacies to sell the anti-flu drug without doctors’ prescriptions, especially when the city is panicking.
Their concern was substantiated in a letter from the Centre for Health Protection to all doctors last month, reminding them that Hong Kong has, for the first time, detected that Tamiflu is ineffective against a common flu strain, influenza A (H1N1).
The center said European seasonal influenza surveillance reports have indicated some A (H1N1) viruses in circulation this winter were resistant to oseltamivir – the generic name for Tamiflu.
About 13% of H1N1 solates sampled late last year from across Europe showed resistance.
Hong Kong’s public health laboratory, though, detected no Tamiflu resistant influenza viruses in both 2006 and 2007. But in January this year, five resistant H1N1 viruses were detected out of 62 samples.
The center said it is monitoring the situation closely.
Chan told The Standard his research up to 2006 showed H3N2, another common flu strain for this year, had not been found resistant to Tamiflu.
“But we are uncertain of the current situation. Tamiflu is a very effective flu drug and also the last weapon to fight H5N1. We cannot afford to jeopardize its efficacy,” Chan said.
He said the resistance rate of Amantadine, an older flu drug, has hit 69% – making Tamiflu the only option for tackling the spread of flu.
Hon expressed worries that family doctors and pediatricians would be under pressure from parents to prescribe flu drugs after the city was shocked by the death of three-year-old Ho Po-yi, who contracted the H3N2 flu virus.
Her six-year-old sister, who came down with flu symptoms, also tested positive for the same flu strain.
But patients who present flu-like symptoms may not have contracted influenza, making Tamiflu inappropriate and increasing the risk of drug resistance, said Hui who, together with his team, recently released a study on 194 elderly people with flu-like illness.
The findings showed their illnesses were mainly caused by bacterial and viral infections other than influenza.
“Flu patients with minor symptoms such as a running nose and sneezing usually don’t need Tamiflu as they already have background immunity. Of course, they should see doctors if the symptoms continue,” he said.