An illustration of a strain of influenza Shutterstock A scientist who carried out research on making influenza viruses more infectious has deliberately created a potentially lethal strain of flu that can evade the human immune system.

Yoshihiro Kawaoka of the University of Wisconsin-Madison has genetically manipulated the 2009 strain of pandemic flu in order for it to “escape” the control of the immune system’s neutralising antibodies, effectively making the human population defenceless against its reemergence.

Most of the world today has developed some level of immunity to the 2009 pandemic flu virus, which means that it can now be treated as less dangerous “seasonal flu”.

Professor Kawaoka intentionally set out to see if it was possible to convert it to a pre-pandemic state in order to analyse the genetic changes involved, the Independent said.

The study is not published, however some scientists who are aware of it are deeply concerned that Dr Kawaoka was allowed to deliberately remove the only defence against a strain of flu virus that has already demonstrated its ability to create a deadly pandemic that killed as many as 500,000 people in the first year of its emergence.

Professor Kawaoka has so far kept his research secret but admitted that the work is complete and ready for submission to a scientific journal. The experiment was designed to monitor the changes to the 2009 H1N1 strain of virus that would enable it to escape immune protection in order to improve the design of vaccines, he said.

“Through selection of immune escape viruses in the laboratory under appropriate containment conditions, we were able to identify the key regions [that] would enable 2009 H1N1 viruses to escape immunity,” Professor Kawaoka said in an email.

“Viruses in clinical isolates have been identified that have these same changes in the [viral protein]. This shows that escape viruses emerge in nature and laboratory studies like ours have relevance to what occurs in nature,” he said.

Prior to his statement to The Independent, Professor Kawaoka’s only known public mention of the study was at a closed scientific meeting earlier this year. He declined to release any printed details of his talk or his lecture slides.

The work was carried out at Wisconsin University’s $12m (£7.5m) Institute for Influenza Virus Research in Madison which was built specifically to house Professor Kawaoka’s laboratory, which has a level-3-agriculture category of biosafety: one below the top safety level for the most dangerous pathogens, such as Ebola virus.

However, this study was done at the lower level-2 biosafety. The university has said repeatedly that there is little or no risk of an accidental escape from the lab, although a similar US Government lab at the Centers for Disease Control and Prevention in Atlanta with a higher level-3 biosafety rating was recently criticised over the accidental exposure of at least 75 lab workers to possible anthrax infection.

Professor Kawaoka’s work had been cleared by Wisconsin’s Institutional Biosafety Committee, but some members of the committee were not informed about details of the antibody study on pandemic H1N1, which began in 2009, and have voiced concerns about the direction, oversight and safety of his overall research on flu viruses.

Rebecca Moritz, who is responsible for overseeing Wisconsin’s work on “select agents” such as influenza virus, said that Professor Kawaoka’s work on 2009 H1N1 is looking at the changes to the virus that are needed for existing vaccines to become ineffective.

“With that being said, this work is not to create a new strain of influenza with pandemic potential, but [to] model the immune-pressure the virus is currently facing in our bodies to escape our defences,” Ms Moritz said.

“The work is designed to identify potential circulating strains to guide the process of selecting strains used for the next vaccine…The committee found the biosafety containment procedures to be appropriate for conducting this research. I have no concerns about the biosafety of these experiments,” she said.

Professor Kawaoka said that he has presented preliminary findings of his H1N1 study to the WHO, which were “well received”.

“We are confident our study will contribute to the field, particularly given the number of mutant viruses we generated and the sophisticated analysis applied,” he said.

“There are risks in all research. However, there are ways to mitigate the risks. As for all the research on influenza viruses in my laboratory, this work is performed by experienced researchers under appropriate containment and with full review and prior approval by the [biosafety committee],” he added.