WHAT IS H3N2?
It's a strain of influenza that is particularly virulent within Australia this year. More than 5000 cases of the H3N2 and Type B strains have been diagnosed across the country already this season, according to data provided from the Department of Health and Aging to the Influenza Specialist Group (ISG) this week.
WHY IS THE H3N2 STRAIN A MAJOR CONCERN RIGHT NOW? HASN'T IT BEEN AROUND FOR YEARS?
The current strain has been around for 44 years, says Professor Robert Booy from the Influenza Specialist Group at the University of Sydney. It is an RNA virus, which are problematic to prevent because they are constantly mutating. “These viruses are poor at accurately copying themselves when they replicate, so that means that instead of being a clone, one virus is slightly different to the next one.”
The virus is therefore able to out-race our natural barrier to infection – building up antibodies over time.
WHY IS IT CONSIDERED DANGEROUS?
It's the volume of cases being reported that are most concerning to Australian scientists, says Dr Ian Barr of the World Health Organisation Collaborating Centre for Reference and Research, based in Melbourne. “The unusual thing is we haven't seen the virus circulate in large numbers since 2007.”
The Google data resource Flu Trends, supported by scientists, shows a significant jump in flu activity this winter, compared to 2011 (see image below) and 2010.
WHO IS MOST AT RISK?
Children under nine have been the hardest age group hit by infection, but the very elderly – those over 75 – are considered most at risk, because there is a higher chance of infection leading to death.
Indigenous Australians are also at increased risk, says Professor Booy. “[This is] partly because, on average, their living conditions are poorer and more crowded, and partly because they have more chronic diseases,” he says.
IS IT TOO LATE TO VACCINATE?
Vaccination is “the safest and the most effective way to protect against life threatening infections like influenza,” says Professor Booy. He says it's still possible to go to your GP and get a preventative jab.
It's not too late if you haven't already had the flu this year, adds Dr Barr. Flu data show seasons with a severe uptake reach a peak, and we haven't yet seen this season's peak.
That means the worst could be yet to come. “It's hard to say whether it will keep going up or tail off,” Professor Booy says.
HOW ELSE CAN YOU PREVENT GETTING THE FLU?
Antiviral medication may be an option, particularly for the elderly or other high-risk groups. Visit your GP for more information.
Regular hand-washing, staying away from people who are coughing and sneezing and staying home if you are sick are the best ways to prevent illness, Professor Booy says. “And smile instead of shaking hands."