Beijing moved additional lessons online on Thursday, strengthening COVID-19 restrictions even more as the Chinese capital tries to avert a bigger outbreak.

The metropolis of 21 million people has already ordered three rounds of mass testing for the virus this week, with the third scheduled on Friday, and has shut down several neighborhoods where cases have been discovered.

It switched most pupils in Chaoyang’s large district to online instruction on Thursday, with the exception of middle and high school students studying for important tests that might determine their academic prospects.

On Thursday, Beijing revealed 50 additional cases, two of which were asymptomatic, bringing the total number of cases in the newest wave of illnesses to roughly 150. Students account for more than a third of all cases, with clusters in Chaoyang related to six schools and two kindergartens.

At least three other districts had already switched their kids to the internet, and officials in Chaoyang published guidelines on Thursday mandating people to stay within two housing blocks where instances had been discovered.

While case counts remain low and the outbreak’s scope is still controllable, Beijing has acted faster than many other Chinese cities to implement restrictions.

The objective is to prevent the kind of draconian restrictions enacted in Shanghai, where the highly transmissible omicron strain has ravaged the 25-million-strong metropolis. Many Shanghai residents have been confined to their homes for the past four weeks, and all schools have been online since last month.

The tight procedures have sparked outrage and irritation over food and basic supply shortages, hospitals’ inability to handle other health problems, and awful conditions at centralized quarantine centers, where anybody who tests positive — or merely had contact with a positive case — must be transported.

On Thursday, the National Health Commission reported 11,285 new cases in mainland China, the most majority of which were asymptomatic and occurred in Shanghai, where 47 more deaths were reported.

Shanghai municipal officials said Wednesday that the findings of further rounds of testing would be analyzed to see whether districts can safely enhance people’ freedom of movement.

Shanghai is aiming for “societal zero COVID,” in which new cases are only discovered in persons who are already under observation, such as in centralized quarantine, or in those who are deemed close acquaintances. That means transmission chains in the open community have been cut, lowering the danger of new clusters emerging from previously unknown sources.

While China’s general vaccination rate is about 90%, just 62 percent of persons over 60 in Shanghai, the country’s largest and wealthiest metropolis, have been vaccinated. According to the city’s Health Commission, health professionals have been visiting senior individuals at home to provide immunizations in an effort to increase that number.

The epidemic has taken a toll on the economy, particularly in Shanghai, which is home to the world’s biggest port and China’s major stock exchange, as well as a huge foreign business population.

According to a study released earlier this month by ING bank, a full month of city lockdown will remove 2% from China’s yearly economic growth. Lockdowns may have an impact on spring planting, driving up food costs, and transportation has been severely impacted.

According to the online official media outlet The Paper, 80 percent of flights at Baiyun Airport in Guangzhou’s southern industrial region were canceled on Thursday after “abnormal findings” were discovered when evaluating airport workers.

The May Day vacation is likely to disrupt travel, particularly between provinces and cities. Since the COVID-19 outbreak was originally found in the central city of Wuhan, China’s foreign borders have remained mainly closed.

Despite Beijing’s vows to lessen the human and economic costs of its stringent “zero-COVID” approach, the Chinese leadership, from President Xi Jinping on down, has ruled out joining the United States and other nations in loosening restrictions and attempting to live with the virus.

According to Gavekal Dragonomics, a research group, all but 13 of China’s 100 largest cities by economic production were under some type of restriction early this month.