China News Service, April 12. According to the official WeChat news of "Taierzhuang Release", on April 12, Taierzhuang District, Zaozhuang City, Shandong Province issued an emergency reminder that a resident of the district did not wear a mask and went to dig wild vegetables somewhere outdoors. An asymptomatic infected person who stayed there who did not wear a mask was infected. After epidemiological investigation and analysis, it was judged that the infection was caused by aerosol transmission.