Gain-of-function research refers to experiments in which viruses are manipulated in laboratory settings to become more virulent. Fauci has long been a proponent of this controversial research, which some scientists consider dangerous for its potential to create new pandemic viruses. When Paul pressed Fauci about these grants in past Senate committee hearings in 2021, Fauci strenuously denied that these grants funded research that would meet the federal government's definition of gain-of-function research. "The [National Institutes of Health] has not ever and does not now fund gain-of-function research" at the Wuhan Institute, said Fauci in response to Paul's questioning during a May 2021 hearing. GOF is the shorthand for gain-of-function research.