Researchers say Indigenous populations have much lower levels of immunity to H7N9, which emerged in China last year

A new, severe version of “bird flu” could pose a significant risk to Indigenous people, after researchers found they were far more susceptible to the virus than other Australians.

A study conducted by the University of Melbourne found that human immunity to the H7N9 influenza virus, which emerged in China last year, varied according to ethnicity.

Researchers tested the prevalence and responsiveness of virus-killing T cells, key in natural immunity, in people of varying ethnicities. While 57% of “Caucasoid” people had a robust T-cell response to the virus, just 16% of Indigenous people in Australia and north America had the same protection.

The H7N9 virus emerged in China in March last year and has so far spread to Hong Kong and Taiwan. It is a strain of the avian influenza, or bird flu, virus that shot to prominence due to pandemic fears over another strain, H5N1.

So far, about 150 people have been infected globally by the H7N9 virus, with around a third of them dying. The University of Melbourne researchers warn that the H7N9 strain, which is spread by birds to humans and has the potential to mutate to allow human-to-human infection, is potentially more dangerous than H5N1.

“The virus is a concern because it has a high mortality rate of around 30% from acute respiratory distress syndrome,” report co-author Katherine Kedzierska, associate professor at the University of Melbourne’s department of microbiology and immunology, told Guardian Australia.

“Humans have no prior history with the virus, so we lack the antibodies to fight it. We looked at cellular immunity, which is our pre-existing immunity, and found the prevalence of T-cell immunity greatly depends on ethnicity.”

Kedzierska said Indigenous people lacked a key protein needed to fight the virus, with their historical isolation making them relatively ill-equipped to deal with new viruses.

“Caucasians have the most immunity because they have adapted to flu viruses and developed mechanisms to fight them off,” she said. “Indigenous people don’t have that, which provides an explanation why there were such high mortality rates from the Spanish flu in 1918, when 10-20% of Indigenous people in Australia died, compared to just 1% of Caucasian people.”

Kedzierska said it was important for the government to factor in the different levels of immunity in different ethnicities when developing responses to flu outbreaks. Researchers are now working on finding ways to boost T-cell immunity in Indigenous communities, in order to develop a tailored vaccine for the virus.