Chinese health officials expressed new optimism Thursday over a deadly virus outbreak while authorities in South Korea’s fourth-largest city urged residents to hunker down as vacillating fears nagged communities far from the illness’ epicenter.

The confidence voiced by China’s government came as it reported a reduced number of new infections. But doubts remained about the true trajectory of the epidemic as China again changed its method of counting and new threats emerged outside the country.

“The downward trend will not be reversed,” insisted Ding Xiangyang, deputy chief secretary of the State Council and member of the Central Government’s supervision group.