The Southeast Asian nation has vaccinated more than 90% of its population of 16 million, for one of the highest rates in the region, official data show. In January, it started rolling out a fourth dose for high-risk groups.
The inoculation drive for toddlers began in the capital of Phnom Penh, with hundreds of people queueing outside clinics where medical staff in personal protection gear gave doses to teary-eyed or wailing children.
"I brought my kid with hope of stopping the spread of COVID-19, and I hope all parents would do so too," said Heng Davy, a 28-year-old mother, as she shuffled along in a fast-moving queue with her son in her arms.
Most countries have yet to start vaccinations for children under the age of five. This month, the United States postponed by at least two months consideration of COVID-19 vaccines for children under five.
China launched a nationwide campaign targeting those aged three to 11 late last year, as did Bahrain, and Cuba has covered those as young as two.
"I would like to thank the government for providing the vaccine for three- to five-year-old kids," said Hour Nary, a father accompanying his daughter while she received the shot.
Cambodia's tally of pandemic infections stands at more than 127,000, with 3,024 deaths.
