BEIJING (BLOOMBERG) - China's Covid-19 outbreak is shifting to its south coast, with a flare-up in technology hub Shenzhen triggering mass testing and a lockdown of some neighbourhoods, while gambling enclave Macau - an hour's drive away - is racing to stop its first outbreak in eight months.

The new cases come as outbreaks in China's two most important cities of Beijing and Shanghai look to be subsiding after months of strict curbs and repeated testing.

Shanghai reported nine local cases on Tuesday (June 21), while Beijing reported five. Nationwide, there were 34 new infections on Tuesday.  

Yet new clusters continue to emerge, prompting action from local officials fearful of spiralling outbreaks.

In Shenzhen, home to companies like iPhone maker Hon Hai Precision Industry, isolation orders were imposed for several residential compounds in the Futian and Luohu districts that border Hong Kong after each reported an asymptomatic infection.

Gaming hub Macau shut schools and non-essential businesses after the government found 36 infections as of Monday afternoon, though casinos remain open.

Fearful of contagion, neighbouring Zhuhai on the mainland locked down the area of the border crossing.

The shifting focus of China's Covid-19 concerns underscores the task of stamping out an infectious pathogen with most of the rest of the world adjusting to living with it.

After damaging outbreaks marred the spring, especially in Shanghai, China is facing pressure to boost economic activity ahead of a party congress later this year where President Xi Jinping is expected to clinch an unprecedented third term as leader.