A total of 15 provinces have confirmed cases of Delta variant with12 of the provinces connected to an outbreak that began in Nanjing in eastern Jiangsu province.
Cases of the variant first emerged in July in Nanjing airport, among workers who had cleaned a plane that arrived from Russia.
Authorities promptly tested 9.2 million residents of Nanjing and imposed lockdown on hundreds of thousands of people.
 Authorities have attributed the spread to the Delta variant and the domestic tourism season.
It is however not clear how many in China are fully vaccinated, although authorities say more than 1.6 billion doses have been administered so far.
The government has imposed fresh travel restrictions and is testing millions with more than 300 cases which have been detected within a span of 10 days.
In Zhuzhou, in central Hunan province, more than a million people have been told not to leave home for three days while mass testing and a vaccination drive is organised. The regional government described the situation there as “grim and complicated”. In other cities entire communities are being placed under emergency lockdown as cases of the Delta variant emerge.
The outbreak is the largest in China for months. The country was largely successful in controlling the virus within its borders last year.
