After Australia has moved beyond flu season, a letter published in the New England Journal of Medicine says the H1N1 influenza virus that is resistant to Tamiflu, a popular antiviral drug, appears to be spreading easily in the country, reports MSN.

World Health Organization (WHO) researchers, who have reported an increased transmission of oseltamivir (Tamiflu)-resistant 2009 A (H1N1) in the flu season, are worried regarding its chances of becoming widespread.

According to the outlining report of Aeron Hurt, PhD, a researcher at the World Health Organization Collaborating Centre for Reference and Research on Influenza in North Melbourne, Australia, and colleagues, of 182 patients affected by influenza virus between May 2011 and August 2011, 29 people (around 16%) were infected with the oseltamivir-resistant virus.

Scientists found that viral samples of 29 patients resistant to oseltamivir and adamantanes were sensitive to zanamivir (Relenza). The news portal learns that among the patients with resistant strain, only one was treated with Tamiflu and three were vaccinated with the 2011 influenza vaccine, prior the sampling.

On conducting the genetic analysis of the strains, researchers found virus strains to be closely related, suggesting the spread of single variant. MSN notes that of 29 patients, most lived within 30 miles radius of Newcastle and were either household contacts or shared car ride.

Expressing his concern over the widespread of resistant strains, the lead researcher told MSN that if the resistant virus spreads beyond the shores of Australia, it will largely affect aged people, increasing the complications in treatment.

Emphasising the importance of immunisation, Dr Len Horovitz, a pulmonary specialist with North Shore-LIJ/Lenox Hill Hospital in New York City, tells the news portal that flu drug is effective only if given within 24 to 48 hours of the onset of symptoms, therefore for protection against influenza, people over the age of 6 months including pregnant women, should take annual flu jabs before the flu season.