Research that involves modifying certain diseases to make them more deadly will again be funded by the US government, writes Sara Reardon for Nature. Scientists can use these so called gain-of-function studies to understand what mutations a virus might need to become more deadly, or understand how a disease interacts with our immune system. But concerns about safety protocols and potential pandemics led the White House to ban funding such research in 2014.

Why it matters: If something goes wrong, such research could have deadly consequences. But proponents argue the knowledge gained can save lives. When the ban was first enacted, it applied to the flu, SARS, and MERS, but some scientists said it was too broad. It initially halted 21 projects — some of which were related to vaccine research, reports Reardon. The moratorium gave the government time to develop a regulatory framework and added layers of security.