China announced mass coronavirus testing in Wuhan after widespread outbreaks of the Delta variant spread to Wuhan. The announcement came as China suspends flights and trains and cancels professional basketball league games.

Although the number of cases remains in the hundreds, it is far greater than any other outbreaks China has faced since the initial one that struck Wuhan in 2020. It spread quickly to the rest of China.

China has not eradicated COVID-19, but it has greatly reduced the spread of the disease at home. There are quick lockdowns and mass tests to isolate new cases. Most of the previous outbreaks never spread beyond a single city or province. This time, there have been cases confirmed in more that 35 cities across 17 of the 31 provinces and regions on mainland China.

Nanjing, Yangzhou and Beijing have cancelled all domestic flights. Beijing also stopped long-distance trains departing from 23 stations. Because of the pandemic, matches in China’s basketball association’s men’s professional league will be suspended.

Wuhan, central China’s provincial capital and home to 11 million people, is the latest city subject to city-wide testing. On Monday, three cases of non-imported drugs were confirmed.

According to the National Health Commission, they were among the 90 newly confirmed cases nationwide on Tuesday. These cases included 61 that were localized and 29 that were among those who arrived recently from overseas.

The majority of local cases remain in Jiangsu, where the outbreak began at Nanjing’s airport and spread to other parts. There were 45 new cases reported by authorities, with five of them in Nanjing, and 40 in Yangzhou, which is 105 km (65 miles) away. A second round of mass testing was in progress.

Five additional provinces, as well as the cities of Beijing & Shanghai, reported new cases within the single digits. A driver who worked at Shanghai’s main airports was positive for the disease. Five cases have been reported in Beijing in the last few days.

The source of most cases in other areas is the Nanjing epidemic, which has been linked to the delta variant. Two other locations have also experienced the delta variant outbreaks. These were linked to Myanmar, which has seen an increase in infections.

A flood that decimated Zhengzhou last month killed approximately 300 people. The outbreak was caused by people who came from Myanmar via air. The third outbreak, which started first, spread from Myanmar’s border to Yunnan.

Government-affiliated scientists have said that Chinese vaccines are less effective against the new strains of the coronavirus but still offer some protection. China is currently using only Chinese vaccines. Authorities have administered more than 1.6 million doses.