Now the shots — which have been offered to those aged 40 and older — are being extended to students above the age of 12 from today.
Lee said health authorities would take advantage of the June school holidays to vaccinate students.
"After the students, we will vaccinate the final remaining group, young adults 39 years and younger," he said.
New variants wreak havoc
Meanwhile, the number of daily new Covid-19 cases in Malaysia has soared past India's on a per capita basis, while total cases in Thailand, Vietnam, Cambodia, Laos, and Timor Leste all more than doubled last month.
Thailand's death toll grew 10-fold over two months — though at just over 1,000, was still low by global standards.
Adding to concerns, Vietnamese officials revealed the discovery over the weekend of a "very dangerous" combination of Indian and UK Covid-19 variants, which spreads quickly by air.
"Covid-19 infection rates are very alarming in countries across South-East Asia," Alexander Matheou, Asia Pacific director for the International Federation of Red Cross and Red Crescent Societies, told Reuters.