Chinese President Xi Jinping on Thursday promised to provide two billion doses of COVID-19 vaccines to the world this year and offered a USD 100 million donation to COVAX, the WHO-backed vaccine alliance, amidst a surge in coronavirus cases of the Delta variant in the country.

The number of active cases in China has crossed over 1,800, including 62 new locally-transmitted ones and 527 asymptomatic cases, the National Health Commission (NHC) said in a report, adding that 1,285 patients are undergoing treatment.

Several Chinese cities, including the central Wuhan where the coronavirus first emerged in December 2019, began mass testing following the emergence of fresh cases, a year after the city brought the contagion under control.

President Xi, in a written speech delivered at the first International Forum on COVID-19 Vaccine Cooperation, said that China will provide a total of two billion doses of COVID-19 vaccines to the world within the year to ensure accessibility and affordability of vaccines.

China will also donate USD 100 million to the COVAX global vaccine programme for the distribution of vaccines in developing countries, Xi said.

The Chinese Foreign Ministry recently said that China has so far provided 750 million vaccine doses to different countries, including 10 million to COVAX.

China has so far administered 1.72 billion vaccines to its people, according to the official media reports.

Xi's promise of two billion vaccines to the world came after US President Joe Biden said on August 3 that America has delivered 110 million COVID-19 vaccine doses to 65 countries, ranging from Afghanistan to Zambia.

The US donations prove that "democracies can deliver," Biden was quoted as saying by the US National Public Radio (NPR).

He also said that the US has acquired another 500 million Pfizer vaccines that will be donated to low- and middle-income countries by the end of the month.

Meanwhile, a Chinese health official downplayed the current surge in COVID-19 cases, saying that China's current virus containment measures are effective against the Delta variant.

Research results and clinical experience at home and abroad showed that the Delta variant had not yet led to fundamental changes in the biological characteristics of the COVID-19 virus, and scientists are basically clear about how the virus is transmitted, He Qinghua, an official with the NHC, told reporters here.

He said that the currently available vaccines can reduce the risk of transmission, and effectively cut the incidence of severe symptoms and lower fatality rate.

The official said that China earlier stopped the spread of the Delta variant successfully in multiple densely-populated regions with high population mobility in Guangdong province, which proves measures including vaccination, wearing masks, washing hands frequently, keeping social distance and avoiding crowded places are effective.