Cambodia launched its coronavirus inoculation drive on Wednesday, using 600,000 vaccine doses donated by China.
First in line to receive the injection were the sons of long-serving Prime Minister Hun Sen and government ministers.
Sen had vowed to take the first dose, but later said that at 68 he was above the age to get the vaccine, made by Sinopharm.
His eldest son Hun Manet, a Deputy Commander of Cambodia's Armed Forces, urged others to get inoculated:
"I appeal to all people, please register your names to receive this vaccination to take part in the prevention of the spread of COVID-19, because this virus is coming out of all of us, so if each and everyone of us can stop (the infection), then we can stop the spread (of this disease)."
The Southeast Asian nation of about 16 million has managed to limit the spread of COVID-19, reporting just 478 infections and no deaths.
The first batch of coronavirus vaccines donated by China arrived in Phnom Penh by special plane on Sunday.
Most of them have been earmarked for health workers and the military.
Beijing has said it will send one million doses of the Sinopharm vaccine to Cambodia, enough for half a million people.