On 1 February 2016, the WHO declared its fourth PHEIC in response to clusters of microcephaly and Guillain–Barré syndrome in the Americas, which at the time were suspected to be associated with the ongoing 2015–16 Zika virus epidemic. Later research and evidence bore out these concerns; in April, the WHO stated that "there is scientific consensus that Zika virus is a cause of microcephaly and Guillain–Barré syndrome." This was the first time a PHEIC was declared for a mosquito‐borne disease. This declaration was lifted on 18 November 2016.