After months of logging only sporadic infections, Cambodia has taken no chances in its battle against COVID-19 by stepping up control measures.

As of Friday, 40 infections linked to the country's first known case of community transmission had been reported since late November, data from Cambodia's Ministry of Health shows.

To control the contagion, Cambodia has closed schools, museums, cinemas and theaters. It has also banned mass gatherings in the capital Phnom Penh and tourism drawcard Siem Reap, and contact tracing has been expanded to more provinces.

The emergence of community transmission has been traced to Nov 28, when six people in a family－members of whom live in the capital and in the northwestern province of Siem Reap－tested positive for the virus.

"The Nov 28th event is the biggest COVID-19 crisis Cambodia has encountered since the beginning of the pandemic," said Veasna Duong, head of the virology unit at the Institut Pasteur du Cambodge, or IPC, a research organization in Phnom Penh. He said it is still uncertain how the transmission will spread.

The IPC, which detected the first COVID-19 case in Cambodia on Jan 27, has been designated the testing center for cases suspected as arising from the community transmission. By Thursday, according to Duong, the virology unit had tested 150,000 samples from Jan 22, including 15,000 linked to the outbreak identified in late November. "The number of samples tested a day reached as high as 3,800," Duong said.

Biggest challenge

"The biggest challenge is that we are not able to identify the source of this community outbreak and that the event occurred during the Black Friday (shopping) event where people massed in shops," he said.

Daniel Tan, Cambodia country coordinator for the Sydney Southeast Asia Centre at the University of Sydney, said the latest cases showed that no country can afford to be complacent with controlling COVID-19.

"Before the first local transmission on Nov 28, Cambodia had relatively effective control measures," said Tan. "By the end of March, Cambodia closed its borders, imposed quarantine requirements, closed schools, encouraged mask-wearing, social distancing and canceled its Khmer New Year holiday."

Despite having far fewer resources for pandemic control than developed countries, Cambodia－with a population of about 16 million－had recorded just about 360 COVID-19 cases as of Sunday, of which most were imported. No deaths related to the virus have been reported.

Cambodia has received recognition for its control measures from the international community, including from World Bank experts.

Li Ailan, the World Health Organization's representative to Cambodia, said the government has strengthened preparedness for large-scale community transmission through a master plan.

Li said that the emergence of a cluster of cases is not surprising given the spread of COVID-19 worldwide.

On Dec 7, Prime Minister Hun Sen said that the kingdom will provide free COVID-19 vaccines to its citizens.

Xinhua contributed to this story.