People queue for nucleic acid tests in Beijing’s Pinggu district on Monday. The capital has tightened restrictions and measures after detecting Covid-19 clusters at two universities. Photo: VCG

Disease control personnel record a person’s information at a Covid-19 testing point in Pinggu district. Beijing reported 114 local cases from Sept. 6 to Wednesday. Photo: VCG

Students and faculty members line up to take nucleic acid tests at Communication University of China in Beijing on Saturday. Clusters have also been discovered at Beijing University of Chemical Technology and the High School Affiliated to Minzu University of China. Photo: VCG

Police inspect the closed northern gate of Communication University of China. The university has been under lockdown since Friday after a case was detected there. Photo: VCG

Student dormitories of the Communication University of China are closed. Photo: VCG

Barricades have been set up at the western gate of Communication University of China. Photo: VCG

A security guard guides a courier outside Communication University of China. Photo: VCG

As of Wednesday, 44 cases have been linked to Communication University of China, including 40 cases found among students and faculty members, and four associated cases, according to the Beijing Center for Disease Prevention and Control. Photo: VCG

Authorities now require travelers to hold a negative nucleic acid test certificate valid within 48 hours to enter or leave the capital by plane, train or bus from Saturday to Oct. 31. Photo: VCG