Benefits of scientific testing in the area are outweighed by risks of pathogenic strains spreading round world, say researchers

Public health experts have warned that controversial experiments on mutant viruses could put human lives in danger by unleashing an accidental pandemic.

Several groups of scientists around the world are creating and altering viruses to understand how natural strains might evolve into more lethal forms that spread easily among humans.

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But in a report published on Tuesday, researchers at Harvard and Yale universities in the US argue that the benefits of the work are outweighed by the risk of pathogenic strains escaping from laboratories and spreading around the world.

They calculate that if 10 high-containment labs in the US performed such experiments for 10 years, the chance of at least one person becoming infected was nearly 20%. If an infected person left the laboratory, the virus might then spread more widely.

“We are not saying this is going to happen, but when the potential is a pandemic, even a small chance is something you have to weigh very heavily,” said Marc Lipsitch, an epidemiologist at Harvard School of Public Health, who wrote the report with Alison Galvani, an epidemiologist at Yale.

The report threatens to reignite a crisis in science that erupted in 2012 when a US biosecurity panel ruled that two separate studies on mutant bird flu were too dangerous to publish. They described the creation of new mutant strains that spread among ferrets – a proxy for humans – held in neighbouring cages. One fear was that the recipe for the pathogens might fall into the hands of bioterrorists.

Those studies, led by Ron Fouchier at Erasmus medical centre in Rotterdam, and Yoshihiro Kawaoka at the University of Wisconsin-Madison respectively, were eventually published after months of delays. Other researchers have now begun similar experiments.

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Both Fouchier and Kawaoka criticised the latest report, published in Plos Medicine, and said their work had full ethical, safety and security approval, with the risks and benefits taken into account.

Last year, the US government, which funds most of the controversial work, revised its guidelines for “dual-use research of concern”, or DURC. Under the new rules, work can be funded if the potential benefits are substantial and the risks considered to be manageable.

But Lipsitch said there was no evidence that the risks and benefits had been weighed up properly. “To my knowledge, no such thing has been done, but funding for these experiments continues,” he said.

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Lipsitch said that the US government and other funding bodies must commission comprehensive risk assessments from independent experts before deciding which studies to support.

Lipsitch and Galvani are most concerned about what are called gain-of-function studies, which aim to create highly virulent strains of viruses in secure laboratories so their genetic codes can be studied. Mutations that make a respiratory virus lodge in the throat, for example, can make the virus more transmissible through coughing.

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The rational for gain-of-function studies is twofold. If scientists can work out which mutations make a virus more dangerous to people, they can improve surveillance by looking out for those mutations in natural strains. The work might also help to steer vaccine development. But Lipsitch argues that neither justification stands up: surveillance is not good enough to use the information, and vaccine developers can do without it, he says.

Rather than creating dangerous viruses in high-containment laboratories, Lipsitch and Galvani urge scientists to pursue alternative routes, for example, comparisons of seasonal human flu strains and other respiratory viruses that have jumped from animals into humans. These are not only safer, the authors claim, but the studies are scientifically sound, because they do not rely on small numbers of animals.

The report was roundly rejected by Fouchier and Kawaoka, two of the leading scientists in gain-of-function studies. Fouchier said the authors were wrong on both points they made – that alternative experiments could provide answers about the transmissibility of viruses, and that the risk of an outbreak or pandemic was high.

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“The research agenda they propose is important and currently ongoing, but alone will never lead to solid conclusions about mammalian adaptation and transmission: the proof of the pudding will need to come from gain-of-function studies using infectious viruses. This is why the department of health and human services has approved our research, taking into account all ethical, safety and security issues, and weighing the risks of the research against the benefits,” Fouchier said.

He said the authors had misinterpreted published data to arrive at their risk of someone picking up a virus in the laboratory. “The truth is that scientific research has never triggered a virus pandemic.” Lipsitch and Galvani point out that a flu strain that spread around the world from 1977 to 2009 was probably released in a laboratory accident.

Kawaoka was similarly unimpressed with the report. “The authors imply that gain-of-function studies are going on without proper reviews. This is not so and suggests they do not understand how highly regulated this work is and the approvals and planning required to conduct this research,” he said. “This commentary lists many experiments they think we should be doing. We are doing many of those experiments already.”

Simon Wain-Hobson, a virologist at the Pasteur Institute in Paris, said that scientists working on the controversial virus studies should be less defensive. “There are times when we have to open up and face our critics. Marc is articulating what many of us feel is obvious,” he said.

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