Public health workers wearing full protective gear have appeared on the streets of northern China, according to footage on social media, evoking memories of the country’s stringent anti-virus measures during the COVID-19 pandemic.

The hazmat-clad personnel were seen spraying disinfectant in public spaces in Sanhe, in China’s northern Hebei Province roughly 50 miles east of capital Beijing, according to the poster of the images and video footage. It remains unclear whether this was a local government initiative or central government directive.

The reemergence of the gear, however, has raised speculation about the potential return of pandemic-era restrictions amid a surge of respiratory illnesses, notably among children, which has strained hospitals in the region. The outbreak is being closely watched by the World Health Organization, the agency said last week.

In the past days, China’s state-controlled media have reported on hospitals in Beijing, Tianjin and other northern areas operating at maximum capacity. Beijing Children’s Hospital alone reported admitting over 7,000 daily cases, one report said.

Patients said they experienced closed outpatient clinics and long lines, some enduring waits of a day or longer at emergency departments.

On Douyin, the Chinese version of the short video-sharing platform TikTok, videos showed disease prevention teams disinfecting a classroom and city streets while dressed from head to toe in hazmat suits.

Termed “dabai,” literally “big white [figures],” the hazmat workers became a symbol of China’s unpopular “zero-COVID” policies that triggered rare anti-government protests late last year. Their appearance has unsettled observers online.