China has detected its two first instances of the omicron Covid variant as the country locked down a major manufacturing hub to contain a separate outbreak

The first case, thought to be a Polish teenager returning to China from abroad, was spotted in Tianjin, a city of 14 million near the capital of Beijing.

A second case was found on Tuesday in Guangzhou, a major manufacturing hub in southern China, also via a traveller, 67, arriving from overseas. 

Both are in mandatory quarantine receiving treatment, according to Chinese state media. 

Chinese officials have said they’re confident the country’s strict testing and sequencing capabilities would provide a strong defence against mass spread of the omicron variant.

China’s borders also remains largely sealed – authorities aren’t renewing or issuing new passports to citizens, visas for foreigners remain hard to obtain, and international flights have been cancelled en masse. 

International arrivals are also subject to as long as 28 days of mandatory quarantine. 

The Chinese government is taking no chances given the onset of winter weather in striving to stay Covid-free, particularly ahead of the Winter Olympics slated for February in Beijing. 

Such stringent measures appear to have been enough to stave off the omicron variant until now. 

Concerns remain that existing vaccines won’t work well against the highly transmissible and heavily mutated variant. 

Gao Fu, the head of China’s centre for disease control and prevention, told state media last week that existing Chinese vaccines would “still work” against omicron.

“But their efficacy is greatly compromised,” he said. “It is hard to tell to what extent.”

In recent weeks, China has also found cases of other variants in Inner Mongolia, Yunnan, and Zhejiang provinces. 

Authorities are scrambling to contain about 100 cases by shutting down factories in Zhejiang – a key production hub – and throwing half a million people in quarantine. 

Officials have continued to install Wuhan-style lockdowns to contain infections.

Hong Kong is expected to add the UK to its list of high-risk countries, reported the city newspaper South China Morning Post on sources, as Britain reported its first death from the omicron variant.