Aerial photo shows the construction site of a centralized medical observation center in Shijiazhuang, capital of north China's Hebei Province, Jan. 14, 2021. Construction workers on Wednesday started building a centralized medical observation center in Shijiazhuang, where clustered COVID-19 cases occurred. The isolation center will likely cover 33 hectares of area near a village in Zhengding County, Shijiazhuang. Three integrated housing producers in Tangshan City, Hebei, have been entrusted to produce 3,000 makeshift wards for the center. Each ward has a space of 18 square meters. (Xinhua/Yang Shiyao)

Workers unload materials at the construction site of a centralized medical observation center in Shijiazhuang, capital of north China's Hebei Province, Jan. 14, 2021. Construction workers on Wednesday started building a centralized medical observation center in Shijiazhuang, where clustered COVID-19 cases occurred. The isolation center will likely cover 33 hectares of area near a village in Zhengding County, Shijiazhuang. Three integrated housing producers in Tangshan City, Hebei, have been entrusted to produce 3,000 makeshift wards for the center. Each ward has a space of 18 square meters. (Xinhua/Yang Shiyao)

Aerial photo shows the construction site of a centralized medical observation center in Shijiazhuang, capital of north China's Hebei Province, Jan. 14, 2021. Construction workers on Wednesday started building a centralized medical observation center in Shijiazhuang, where clustered COVID-19 cases occurred. The isolation center will likely cover 33 hectares of area near a village in Zhengding County, Shijiazhuang. Three integrated housing producers in Tangshan City, Hebei, have been entrusted to produce 3,000 makeshift wards for the center. Each ward has a space of 18 square meters. (Xinhua/Yang Shiyao)

Aerial photo shows the construction site of a centralized medical observation center in Shijiazhuang, capital of north China's Hebei Province, Jan. 14, 2021. Construction workers on Wednesday started building a centralized medical observation center in Shijiazhuang, where clustered COVID-19 cases occurred. The isolation center will likely cover 33 hectares of area near a village in Zhengding County, Shijiazhuang. Three integrated housing producers in Tangshan City, Hebei, have been entrusted to produce 3,000 makeshift wards for the center. Each ward has a space of 18 square meters. (Xinhua/Yang Shiyao)

Aerial photo shows the construction site of a centralized medical observation center in Shijiazhuang, capital of north China's Hebei Province, Jan. 14, 2021. Construction workers on Wednesday started building a centralized medical observation center in Shijiazhuang, where clustered COVID-19 cases occurred. The isolation center will likely cover 33 hectares of area near a village in Zhengding County, Shijiazhuang. Three integrated housing producers in Tangshan City, Hebei, have been entrusted to produce 3,000 makeshift wards for the center. Each ward has a space of 18 square meters. (Xinhua/Yang Shiyao)

Workers unload materials at the construction site of a centralized medical observation center in Shijiazhuang, capital of north China's Hebei Province, Jan. 14, 2021. Construction workers on Wednesday started building a centralized medical observation center in Shijiazhuang, where clustered COVID-19 cases occurred. The isolation center will likely cover 33 hectares of area near a village in Zhengding County, Shijiazhuang. Three integrated housing producers in Tangshan City, Hebei, have been entrusted to produce 3,000 makeshift wards for the center. Each ward has a space of 18 square meters. (Xinhua/Yang Shiyao)

Workers put up prefabs on the construction site of a centralized medical observation center in Shijiazhuang, capital of north China's Hebei Province, Jan. 14, 2021. Construction workers on Wednesday started building a centralized medical observation center in Shijiazhuang, capital of north China's Hebei Province, where clustered COVID-19 cases occurred. The isolation center will likely cover 33 hectares of area near a village in Zhengding County, Shijiazhuang. Three integrated housing producers in Tangshan City, Hebei, have been entrusted to produce 3,000 makeshift wards for the center. Each ward has a space of 18 square meters. (Xinhua/Yang Shiyao)

Aerial photo taken on Jan. 14, 2021 shows the construction site of a centralized medical observation center in Shijiazhuang, capital of north China's Hebei Province. Construction workers on Wednesday started building a centralized medical observation center in Shijiazhuang, capital of north China's Hebei Province, where clustered COVID-19 cases occurred. The isolation center will likely cover 33 hectares of area near a village in Zhengding County, Shijiazhuang. Three integrated housing producers in Tangshan City, Hebei, have been entrusted to produce 3,000 makeshift wards for the center. Each ward has a space of 18 square meters. (Xinhua/Yang Shiyao)

Workers harden the road surface on the construction site of a centralized medical observation center in Shijiazhuang, capital of north China's Hebei Province, Jan. 14, 2021. Construction workers on Wednesday started building a centralized medical observation center in Shijiazhuang, capital of north China's Hebei Province, where clustered COVID-19 cases occurred. The isolation center will likely cover 33 hectares of area near a village in Zhengding County, Shijiazhuang. Three integrated housing producers in Tangshan City, Hebei, have been entrusted to produce 3,000 makeshift wards for the center. Each ward has a space of 18 square meters. (Xinhua/Yang Shiyao)

Workers install power supply equipment on the construction site of a centralized medical observation center in Shijiazhuang, capital of north China's Hebei Province, Jan. 14, 2021. Construction workers on Wednesday started building a centralized medical observation center in Shijiazhuang, capital of north China's Hebei Province, where clustered COVID-19 cases occurred. The isolation center will likely cover 33 hectares of area near a village in Zhengding County, Shijiazhuang. Three integrated housing producers in Tangshan City, Hebei, have been entrusted to produce 3,000 makeshift wards for the center. Each ward has a space of 18 square meters. (Xinhua/Yang Shiyao)