The National Institutes of Health (NIH) in the US is to lift a ban on research that makes viruses more potent or infectious.

A “pause” on such research has been in place since October 2014, following concerns over how risky it was. In 2011, for example, researchers modified H5N1 bird flu to spread between ferrets.

The benefits of such research can allow us to prepare for pandemics. However, there are plenty of critics who think the risks do not outweigh the benefits. This line of research is called “gain-of-function” (GOF). It was announced yesterday that the NIH was lifting the pause after further consultation.

“We have a responsibility to ensure that research with infectious agents is conducted responsibly, and that we consider the potential biosafety and biosecurity risks associated with such research,” Dr Francis Collins, the director of the NIH, said in a statement.

“I am confident that the thoughtful review process laid out by the HHS P3CO Framework will help to facilitate the safe, secure, and responsible conduct of this type of research in a manner that maximizes the benefits to public health.”

Pathogens that will be included in the new research are influenza, middle East respiratory syndrome (MERS), and severe acute respiratory syndrome (SARS). Now, previous research into these diseases using GOF can be reviewed, although it’s not clear if studies that had been put on hold in 2014 will be continued.

Any new research will have to be closely examined before it can be allowed take place. But if controlled safely, it could allow us to see how certain viruses like bird flu mutate and infect humans, a possible step towards creating vaccines.

“The pathogen to be modified must pose a serious health threat, and the work must produce knowledge — such as a vaccine — that would benefit humans,” notes The New York Times. “Finally, there must be no safer way to do the research.”

There will no doubt be continued debate on the positives of GOF research. Some argue that they pose too great a risk of an accidental pandemic without showing many useful results. Others will say that, with more stringent reviews in place, the research could be vital to stopping pandemics in the future.