There is little to suggest that the coronavirus strains currently circulating are more likely to infect children, experts said, even as more than 40 students and pupils from about 30 schools have come down with Covid-19 in the past month.

The reason so many children have been infected, said infectious diseases expert Paul Tambyah, is the environment where most of the cases involving them originated - a tuition centre.

It has become the epicentre of a large cluster, said Professor Tambyah, deputy director of the National University of Singapore's (NUS) Yong Loo Lin School of Medicine's Infectious Diseases Translational Research Programme.

The Learning Point tuition centre cluster had 28 cases as at Friday. On that same day, Singapore reported its first incident of school-based transmission.

However, current evidence does not point to children being more likely to be infected with the B1617 variant that was first detected in India, compared with the original strain.

Official data from the Press Trust of India news agency suggests that the proportion of children infected during the first and second waves of the pandemic in India is similar, Prof Tambyah said.

Associate Professor Sylvie Alonso, co-director of the Infectious Diseases Translational Research Programme, said more aggressive testing among the younger age group could also be a reason for more cases surfacing.

"We seem to also see that the B1617 variant is overall more transmissible than the previous variants - across all age groups - thus affecting more children as well," she added.

Associate Professor Hsu Li Yang, vice-dean of global health at the NUS Saw Swee Hock School of Public Health, said the risk of severe disease for those under the age of 18 is much lower than for adults.

"Babies under one and children with underlying medical conditions such as diabetes and chronic lung disease may be more likely to get severe Covid-19, but generally, those under the age of 18 are far less likely to get severe Covid-19 compared with adults," he said.

There is, however, a very rare and serious condition, known as multisystem inflammatory syndrome - a condition where different parts of the body can become inflamed.

It is seen only in children and is associated with Covid-19 infection, but Singapore has yet to see a case, Prof Hsu said.

Children under the age of 12 are also less likely to get infected, he added.

Still, children remain a weak link in Singapore's fight against Covid-19.

Young children tend not to be able to wear masks or observe safe distancing measures well, Prof Hsu said.

"So, even though they are individually less at risk of serious illness or spreading the virus, collectively, the risk will add up - particularly at tuition centres and other enrichment classes and play locations, where children from multiple schools typically congregate," he added.

Prof Alonso said children who are infected can also be carriers and transmitters of the virus without realising it, because they will be mostly asymptomatic.

She added that this would be a concern if they transmit the virus to vulnerable people in their households who could develop a severe form of the disease.

Prof Tambyah said: "Thus, the idea of vaccinating this age group is that it is a way to protect the vulnerable."

The Health Sciences Authority last Tuesday extended its authorisation for those aged 12 to 15 to receive the Pfizer-BioNTech vaccine.

The Health and Education ministries will announce at a later date when Covid-19 vaccination will be extended to this age group.