The U.S. government has lifted a temporary ban on research attempting to develop an animal model for the MERS (Middle East respiratory syndrome) virus, a deadly coronavirus spreading from camels to people in the Middle East.

On 17 October, in an unusual move, the U.S. government halted federal funding for risky studies on MERS, SARS, or influenza that tweak these viruses to make them more pathogenic or transmissible by respiration in mammals. Among the 18 stopped projects were at least five working on adapting the MERS virus to mice in order to generate a strain that sickens the animals. That could ease studies aimed at understanding the virus and developing vaccines and drugs.

The funding pause came as a shock to MERS researchers. At various meetings, including one at the National Academy of Sciences this week, they argued that developing an animal model for MERS is crucial for addressing the virus, which has infected at least 938 people and killed one-third of them. They applied for an exemption, spelled out in the moratorium policy, that allows for continuing work “urgently necessary to protect the public health.”

That exemption has now been approved for at least some of these projects. “We are very happy,” says Matthew Frieman of the University of Maryland School of Medicine in Baltimore, who got a call from his program officer at the National Institute of Allergy and Infectious Diseases (NIAID) yesterday. NIAID intramural researcher Kanta Subbarao said her project to develop a rabbit model for MERS has also been exempted; the National Institutes of Health had not responded to a request about the other projects at press time.

*Update, 18 December, 3:20 p.m.: NIH confirmed today that all five projects working on a mouse model for MERS have been exempted from the pause. Two influenza studies have also been granted an exception; no requests for an exemption have been denied.