A health worker prepares a dose of China's Sinovac COVID-19 vaccine at a vaccination site at the Diamond Island in Phnom Penh, Cambodia, on May 12, 2021. To date, more than 1.82 million out of the country's 16 million population had been vaccinated against the virus, a government report said. (Photo by Phearum/Xinhua)

People receive their first doses of China's Sinovac COVID-19 vaccines at a vaccination site at the Diamond Island in Phnom Penh, Cambodia, on May 12, 2021. To date, more than 1.82 million out of the country's 16 million population had been vaccinated against the virus, a government report said. (Photo by Phearum/Xinhua)

A man receives his first dose of China's Sinovac COVID-19 vaccine at a vaccination site at the Diamond Island in Phnom Penh, Cambodia, on May 12, 2021. To date, more than 1.82 million out of the country's 16 million population had been vaccinated against the virus, a government report said. (Photo by Phearum/Xinhua)

People wait at a vaccination site at the Diamond Island in Phnom Penh, Cambodia, on May 12, 2021. To date, more than 1.82 million out of the country's 16 million population had been vaccinated against the virus, a government report said. (Photo by Phearum/Xinhua)