BEIJING, AUGUST 03

Chinese authorities announced Tuesday mass coronavirus testing in Wuhan as an unusually wide series of COVID-19 outbreaks reached the city where the disease was first detected in late 2019.

Wuhan, a provincial capital of 11 million people in central China, is the latest city to undergo city-wide testing. Three cases were confirmed there on Monday, its first non-imported cases in more than a year.

China has largely curbed COVID-19 at home after the initial outbreak that devastated Wuhan and over time spread to the rest of China and globally. Since then, authorities have tamped down and controlled the disease whenever it pops up with quick lockdowns and mass testing to isolate infected people.

The current outbreaks, while still in the hundreds of cases in total, have spread much more widely than previous ones, reaching multiple provinces and cities including the capital, Beijing. Many of the cases have been identified as the highly contagious delta variant that is driving a resurgence in many countries.

The National Health Commission said Tuesday that 90 new cases had been confirmed the previous day, 61 locally spread ones and 29 among people who had recently arrived from abroad.

Most of the local cases are still in Jiangsu province, where an outbreak started at the airport in Nanjing, the provincial capital, and has spread to the city of Yangzhou, 105 kilometers (65 miles) away. Authorities reported 45 new cases, five in Nanjing and 40 in the city of Yangzhou, which was conducting a second round of mass testing,

Five other provinces and the cities of Beijing and Shanghai reported new local cases in the single digits. In Shanghai, the nation's largest city, a driver working at one of its two main airports tested positive. Beijing has reported a total of five cases in recent days.

Government-affiliated scientists have said that Chinese vaccines are less effective against the new strains of the coronavirus but still offer some protection. Only Chinese vaccines are currently being given in China, where authorities say more than 1.6 billion doses have been administered.