Staff members transport China's Sinovac COVID-19 vaccines at the Phnom Penh International Airport in Phnom Penh, Cambodia, July 31, 2021. A plane carrying a new batch of Sinovac COVID-19 vaccine landed in Phnom Penh, capital of Cambodia, on Saturday, giving another boost to the country in its vaccination drive. (Photo by Phearum/Xinhua)

A batch of China's Sinovac COVID-19 vaccines arrives at the Phnom Penh International Airport in Phnom Penh, Cambodia, July 31, 2021. A plane carrying a new batch of Sinovac COVID-19 vaccine landed in Phnom Penh, capital of Cambodia, on Saturday, giving another boost to the country in its vaccination drive. (Photo by Ly Lay/Xinhua)

A staff member transports China's Sinovac COVID-19 vaccines at the Phnom Penh International Airport in Phnom Penh, Cambodia, July 31, 2021. A plane carrying a new batch of Sinovac COVID-19 vaccine landed in Phnom Penh, capital of Cambodia, on Saturday, giving another boost to the country in its vaccination drive. (Photo by Phearum/Xinhua)