HONG KONG—China logged its highest daily total of locally transmitted Covid-19 infections in more than two years, with the highly transmissible Omicron variant of the coronavirus posing a fresh test to China’s ability to quickly smother outbreaks.

China’s National Health Commission said Monday that it had detected 526 domestic infection cases, 214 of which were symptomatic, on the prior day, marking the single highest daily tally by either measure since the initial pandemic outbreak in the central Chinese city of Wuhan in...

HONG KONG—China logged its highest daily total of locally transmitted Covid-19 infections in more than two years, with the highly transmissible Omicron variant of the coronavirus posing a fresh test to China’s ability to quickly smother outbreaks.

China’s National Health Commission said Monday that it had detected 526 domestic infection cases, 214 of which were symptomatic, on the prior day, marking the single highest daily tally by either measure since the initial pandemic outbreak in the central Chinese city of Wuhan in early 2020.

Most of those who tested positive on Sunday were in the eastern port cities of Qingdao and Shanghai, with others detected in the southern province of Guangdong and the northeastern province of Jilin.

For now, China is sticking to what it calls a “dynamic clearing” policy that requires local authorities to bring any outbreak under control as quickly as possible by identifying the source of the outbreak and isolating all infected patients and their close contacts.

At the same time, Chinese health experts have begun exploring options to pivot away from the current pandemic-response model, such as tinkering with its current combination—effective but laborious and costly—of digital surveillance, tight border controls, mass testing and targeted lockdowns to prevent and suppress larger outbreaks.

The flareup in Qingdao centers on middle-school students and teachers in Laixi county, accounting for most of Monday’s 163 newly identified cases in the city. All of them were found to have been infected with the highly virulent Omicron strain and were identified through mass testing of more than 3,000 people classified as close contacts of several infected students, according to data provided by local health authorities.

The roughly 60 new cases in northeastern Jilin were detected during a round of citywide mass testing, according to local media reports.

In Shanghai, almost all of the 48 cases identified there were travelers from Hong Kong who were undergoing a 14-day hotel quarantine.

Wu Jinglei, director of the Shanghai Center for Disease Control and Prevention, told a press conference Sunday that the number of hospitalized cases had hit a record for Shanghai, and that 230 medical staff had been dispatched to treat patients. Under China’s current Covid-19 policy, every positive case, regardless of severity, is sent to a medical facility for treatment.

As countries loosen Covid-19 restrictions, Hong Kong is sticking to a 'dynamic zero-Covid' approach – with help from Beijing. A surge in cases has overwhelmed hospitals and threatens business confidence in the global financial hub. Photo: Bertha Wang/Bloomberg The Wall Street Journal Interactive Edition

Hong Kong, which is struggling with a severe outbreak that added more than 25,000 newly confirmed cases on Monday, has also been driving the high number of infections in neighboring Guangdong province. All of the 153 positive test results detected in the manufacturing hub of Dongguan, not far from Hong Kong, were found among people in centralized quarantine for close contacts.

As of Sunday, Chinese health authorities said they had officially recorded 102,722 symptomatic Covid-19 cases in mainland China, resulting in 4,636 deaths, since the beginning of the pandemic.

—Yueling Zhao contributed to this article.

Write to Sha Hua at sha.hua@wsj.com