Late last week, the White House Office of Science and Technology Policy and the US Department of Health and Human Services announced an immediate pause in all new government funding for gain-of-function (GOF) research — experiments to boost the transmissibility, virulence or host range of pathogens — on influenzas, Middle East respiratory syndrome and severe acute respiratory syndrome.

The pause is to allow time to develop a new policy on how such work should be conducted and regulated. The policy will be informed by a full assessment of the risks and benefits of the work, and by how these compare with those for safer alternatives. In charge of that assessment is the National Science Advisory Board for Biosecurity (NSABB), which is meeting this week for the first time in two years (see page 411). The board will also advise on the policy’s content. In parallel, the National Research Council (NRC) of the National Academies will convene a scientific conference on the issues surrounding GOF research, including its risks and benefits. It will also review the NSABB’s draft recommendations for the new policy.

Controversy over GOF research was first sparked in late 2011 when the NSABB attempted to stop the publication of the full results of two studies in which the H5N1 avian flu virus had been engineered to become transmissible in mammals. The board and others were worried that information in the papers could help terrorists or other malevolent individuals to develop a bioweapon. Those concerns were finally overruled, and on 24 September, the United States adopted new rules on what is known as dual-use research — work that could be misapplied to do harm — on 15 pathogens or toxins.

A wider concern raised at the time — which has since shifted to front and centre — was the risk of a pathogen that had been engineered to become more dangerous escaping from the lab. In February 2012, the US Department of Health and Human Services added another layer of review for grant proposals involving GOF research, but only for H5N1; this was extended to H7N9 in August 2013. The research community became deeply polarized over the issues surrounding GOF work. Some vaunted the benefits of such research for pandemic preparedness and down-played biosafety and biosecurity risks, whereas others argued that the experiments should not be done because the risks far outweighed the benefits. To allow time for debate, GOF researchers agreed to put their research on hold, resuming work a year later after deciding that enough time had passed.

The climate for constructive discussion is now perhaps better than it was.

The decision to implement another moratorium — and to broaden it to pathogens other than the H5N1 and H7N9 flu viruses — is a belated acknowledgement that the issue of how to handle GOF research is far from resolved. And the revelations over the past few months of serious violations and accidents at some of the leading biosafety containment labs in the United States has burst the hubris that some scientists, and their institutions, have in their perceived ability to work safely with dangerous pathogens. The US administration cited these revelations as one reason for the latest review; behind-the-scenes lobbying by critics of GOF research also played a part.

The climate for constructive discussion is now perhaps better than it was: although opinions remain sharply divided, each side now seems to be listening more to the other. In July, almost 300 scientists and policy experts signed up to the ‘Cambridge Consensus’, which criticized the lack of a proper risk–benefit assessment of the research, and called for exactly what the US government has now agreed to do. More than 200 scientists responded with ‘Scientists for Science’, which defended GOF research and the ability to carry it out safely, but acquiesced on the possibility of further discussion, as long as it was done “under the auspices of a neutral party”, such as the US National Academy of Sciences.

In a sign of the potential for common ground, Ian Lipkin, a renowned virus hunter at Columbia University in New York, saw fit to sign both calls. Both arguments have merit, he says, but both are also incomplete. Last week, a group of scientists including both opponents and supporters of GOF flu research, published a sober assessment of the potential and limitations of current approaches to assess the potential pandemic risk of various flu viruses (C. A. Russell et al. eLife 3, 03883; 2014). It paints a much more nuanced picture than some of the bold claims made earlier for GOF research. We need more such balanced analyses, and fewer dogmatic opinions, on both sides.