A gathering number of new influenza strains in the past five years has escalated the likelihood of a major influenza pandemic on the scale of the deadly Spanish flu, researchers say.
UNSW researchers in the school of public health are calling for better collaboration between countries and first responder agencies in the event of a flu pandemic.
Their study published in the Archives of Public Health identified 19 separate influenza strains that have emerged in humans during the past century, including seven in the past five years alone.
Raina MacIntyre, director of the UNSW’s Integrated Systems for Epidemic Response, said the unprecedented rise in new strains appeared to be a true increase and not just a matter of more cases being detected.
“The question is, why?” Professor MacIntyre said.
“Some of the reasons involve things like climate change and its impact on pathogens, changes like urbanisation, but none of these things have increased at the rate the virus is increasing so there’s something else going on.”
The Spanish flu, which killed 50 million people in 1918-19, was followed by a 40-year hiatus during which no new flu strains emerged, and then a 10-year gap from the one after that to the next.
But the emergence of strains has gathered pace in the past 15 years.
Professor MacIntyre said a repeat of the Spanish flu was “very possible” and countries and sectors such as health, agriculture, defence and emergency services needed to collaborate better on how to respond in such an event.
“We are somewhat prepared, but when pandemics occur there are almost always unanticipated scenarios,” she said.
“When health systems become stressed and unable to cope with the sick, that is when we are truly tested.”
Influenza strains that have developed in recent years have been transmissible only from birds to humans and not between people, and fatalities have been rare.
But study co-author Chau Bui said the large number of viruses circulating among birds in recent years increased the likelihood that one would mutate and become transmissible between humans.
The risks could be mitigated by banning the sale of live birds in wet markets in Asia, thereby reducing the spread of viruses between birds, and controlling the purchase of live or freshly slaughtered poultry in wet markets to stop the public coming into contact with the bodily fluids of infected poultry, she said.
Special Interest Group for Influenza chair Alan Hampson, who was not part of the study, said there needed to be more research into the genetics of influenza viruses because if they were able to bind to human receptors, or survive in the air, then person-to-person transmission would become more likely.
“These viruses are reinventing themselves all the time,” Dr Hampson said.
“Most people think it’s highly probable that we will have influenza pandemics in the future and it may come from a source that’s being looked at under the World Health Organisation surveillance program or it may be like the one in 2009 that came out of left field and took us all by surprise.”
Meanwhile, a study by the US Centre for Disease Prevention and Control has found that flu vaccinations significantly reduce a child’s chances of dying from influenza.
Using data from 2010 to 2014, the researchers found only one in four children who died had been vaccinated.