Singapore will stop most school classes this week following a spike in COVID-19 cases where the infection route could not be traced, which pose the biggest challenge since last year to the government as it works out plans to vaccinate children.

All primary, secondary, junior college and some pre-university students will shift to full home-based learning, a move last carried out in April last year as part of a partial lockdown. The Education Ministry said that this time schooling from home will run from May 19 until the end of the school term, on May 28.

"Some of these mutations are much more virulent and they seem to attack the younger children,” said Chan Chun Sing, the new education minister, at a briefing. "We have to significantly reduce our movement and interactions in the coming days.”