BEIJING, Dec 22 (Reuters) - China reported 77 new confirmed coronavirus cases for Dec. 21, down from 81 a day earlier, its health authority said on Wednesday. Of the new infections, 57 were locally transmitted, according to a statement by the National Health Commission, unchanged from a day earlier. Most of the new local cases were in the northwestern province of Shaanxi. China reported 19 new asymptomatic cases, which it classifies separately from confirmed cases, also unchanged from a day earlier. There were no new deaths, leaving the death toll at 4,636. Mainland China had 100,544 confirmed cases as of Dec. 21.