Australasian Science: Australia's authority on science since 1938

Flu Recombination Risk High

Flu image

A future pandemic with more severe effects than last year’s could gain resistance through co-infection with a seasonal variety.

By Stephen Luntz

The discovery of high rates of co-infection between two versions of the flu virus has raised the danger of a drug-resistant flu pandemic.

“Last year our influenza season began with the circulation of the regular seasonal A/H1N1 strain, which is Tamiflu-resistant,” says Dr Matthew Peacey of New Zealand’s Institute of Environmental Science and Research. “This seasonal A/H1N1 strain was rapidly overtaken by the worldwide pandemic A/H1N1 strain. In New Zealand there was a short 4–5-week period when both strains were circulating within the community, and in some cases both strains were able to infect a single patient.”

One of the things that makes flu such a hard disease to stop is its capacity to shuffle its genes when two versions infect the same individual. However, this shuffling is usually thought to take place in pigs.

“Very little research has been done on co-infection,” Peacey says. “To find so many cases within a fortnight where the pandemic overtook regular seasonal flu is a surprise.”

The overwhelming majority of seasonal A/H1N1 viruses are Tamiflu-resistant, so there is a great danger that any recombination could produce a version of the flu that could spread as quickly as the pandemic version while maintaining Tamiflu resistance.

Fortunately Peacey says that the danger would be small if this happened now with H1/N1. “The population now has had some exposure to both seasonal and pandemic versions, so there is some immunity to both.”

However, a future pandemic with more severe effects than last year’s could gain resistance through co-infection with a seasonal variety.

The findings were published in Emerging Infectious Diseases.