China’s strict zero-COVID strategy may not be as effective as once thought, as more cases have been reported on some local levels. China, which has a population of 1.3 billion, has blamed most of its cases since the initial Wuhan outbreak on foreign visitors. 

China implemented a 21-day quarantine mandate for those traveling into the country, and is considered to have one of the world's most “far-reaching containment measures.” 

But are the measures working?

A recent outbreak infected 60 people in the southeast city of Fujian. Officials cited an infected male traveler for the outbreak. 

The man completed the 21-day mandatory quarantine and didn’t test positive for COVID until the 37th day of his stay. He had tested negative for COVID nine times while in quarantine, according to state media. It is unclear if the man became infected while in China or if he was infected in another country.

Researchers at the Guangdong Provincial Center for Disease Control and Prevention say that the Delta variant only has an average incubation period of four days. 

China’s last outbreak infected over 1,200 people despite the zero-COVID strategy. Outbreaks have also recently been reported in nearby cities Quanzhou and Xiamen, China’s National Health Commission said Monday. 

Uncertainty surrounds whether to continue the zero-COVID strategy with the mixed results.

"It'll become more and more difficult to sustain that approach, in terms of the time, the organizational energy, and the financial and economic pains it takes to reset cases to zero," said Yanzhong Huang, a senior fellow for global health at the Council on Foreign Relations.

"No matter how stringent the travel restrictions are, you'll continue to have cases imported and triggering outbreaks in the country."