Spike in Covid-19 cases in China caused by Delta variant: officials

China's national capital on Monday classified one area as medium-risk and a residential community as high risk for COVID-19 as total cases in the city rose to 21 while 33 cases were reported in different parts of the country, which officials attributed to virulent Delta variant.

A residential community in Changping district of Beijing was classified as a medium-risk area after reporting two locally transmitted confirmed COVID-19 cases, Pang Xinghuo, deputy director of Beijing's centre for disease control and prevention, said on Monday.

The centre earlier classified another residential community in Changping district as high-risk for COVID-19. With the exception of these two areas, the city is low-risk for COVID-19, state-run Xinhua news agency reported.

The sudden spike in COVID-19 cases made officials ramp up control measures as the Chinese capital, which hosts the top leadership of the country, geared up to hold the winter Olympics in February.

The new infections in the city were caused by the Delta variant, and most of the infected are above 55 years old, Pang said.

Epidemiological investigation and viral genome sequencing results have indicated that this new round of COVID-19 infections in China was caused by viruses transmitted from abroad, according to the National Health Commission (NHC).

The Delta variant is behind the fresh COVID-19 cases, Wu Liangyou, an official with the NHC, said at a press conference. Wu said that efforts are still being made to trace the origins.

The NHC in its daily report on Monday said the Chinese mainland on Sunday reported 33 new locally transmitted COVID-19 cases excluding Beijing.

The new cases were reported from Inner Mongolia, Guizhou, Gansu, Hebei, Hunan and Shaanxi, the commission said.

Sunday also saw Tianjin, Shanghai, Shandong and Guangxi each report one new imported case.

The total number of confirmed COVID-19 cases on the mainland had reached 96,797 by Sunday, including 573 patients still receiving treatment. Among them, 20 were in severe condition, it said.

So far, 4,636 people have died as a result of the coronavirus since last year, according to NHC.