KUALA LUMPUR: The surge in Covid-19 infections and hospitalisations among infants, toddlers and children in recent weeks has raised concerns that the Omicron variant may pose a greater threat to this age group than its predecessor variants.

Experts said children, especially those under the age of 5, were one of the most vulnerable populations in this pandemic since they were still not eligible for Covid-19 vaccines.

Therefore, they said, apart from strict compliance with public health measures, those eligible for vaccines and booster doses should get inoculated immediately to reduce the risk of infection.

They said this included pregnant women as a recent study by the United States Center for Disease Control and Prevention (CDC) had found that getting an mRNA vaccine during pregnancy might help protect infants less than 6 months of age from hospitalisation due to Covid-19.  

Molecular virologist Dr Vinod Balasubramaniam of the Jeffrey Cheah School of Medicine and Health Sciences at Monash University Malaysia said until very recently (before the emergence of Delta and Omicron) if there was one silver lining to the pandemic, it was that children seemed to escape the worst of the coronavirus.

"Very few became seriously ill or even mildly sick, compared with adults. But now the number of children, especially in the younger age group of below 5, infected and hospitalised with Covid-19 has skyrocketed, raising concerns that the latest version of the coronavirus may be a greater threat to children," he told the New Straits Times.

Malaysia this year reported 46,194 Covid cases in children, involving 16,810 children under the age of 6, and 29,384 cases among children aged between 5 and 11.

Some 16,959 infections in children under 12 were reported during the sixth epidemiological week (Feb 6 to 12), a sharp rise of 160 per cent from the 6,524 cases recorded in the fifth epidemiological week (Jan 30 to Feb 5).

Of the 16,959 cases, 6,163 involved children under the age of 5 and 10,796 among children aged 5 to 11.

Three Covid-19 deaths involving children under 12 (two of the cases among children below 5) were also reported up to Feb 15. Malaysia also recorded a spike in Covid-19 paediatric hospital admissions.

Dr Vinod said the jump in cases and hospitalisations were likely the result of a confluence of factors, one of them being Omicron's more contagious nature.

Another, he said, might be the variant's newfound preference for airway passages above the lungs, which could be more easily blocked in small children.

"In the first wave of the pandemic, children mostly fared better than adults because children have more robust innate immune systems, which mount rapid initial responses to invading microbes.

"Adults, in contrast, have better adaptive immune systems, which respond effectively after an infection has begun to take hold in the body."

He said Omicron replicated 70 times faster than Delta in human airways, according to data shared in a news release from the University of Hong Kong.

The same research and a slew of animal studies had shown that the variant had a harder time multiplying in lung tissue, suggesting why it might cause less severe disease, he said.

However, he said, Omicron's preference for the respiratory tract above the lungs could spell trouble for younger children, whose airways were narrower and less developed.

"This is because it is easier for these tiny airways to be obstructed by mucus and inflammation, causing infants and toddlers to develop wheezing or croup, a disease known for its characteristic barking cough."

It was reported that a vaccine for children younger than 5 would be available later this month or early next month after Pfizer and BioNTech requested the US Food and Drug Administration (FDA) use emergency authorisation of a two-dose series of vaccine for children aged 6 months to 4 years.

The FDA expert committee was scheduled to meet on Feb 15 to discuss the authorisation, but the meeting was postponed, while Pfizer gathers more data from its ongoing clinical trial on a three-dose regimen.

"The data is expected to be available in April. There are no concerns on its safety, but rather on the efficacy of this vaccine with a three-dose regimen," Dr Vinod said, adding that a CDC study, however, found that babies less than 6 months old whose mothers were vaccinated were 61 per cent less likely to be hospitalised with Covid-19.

On "long Covid" among children, Dr Vinod said one of the main problems in Malaysia was that only a fraction of children sought medical attention, which made tracking its incidence challenging.

"Symptoms like fatigue, for instance, can manifest in young children as hyperactivity rather than sluggishness, making it difficult for parents to detect the problem. Thus, we are likely only identifying the adolescents who can self-report their symptoms."

With long Covid, he said, many children suddenly found themselves struggling to keep up with their schoolwork or skipping sports, while others could not sleep, had difficulty walking, and struggled with aches and pains, breathlessness and dizziness.

Dr Vinod added that there was no one-size-fits-all treatment for long-Covid as each symptom was addressed individually.

On close contacts who were up to date with their vaccinations (including booster doses) and had previously contracted Covid-19 (within three months) not requiring quarantine, Dr Vinod said this was in line with international standards including those recommended by the CDC.

"Those who had their booster doses are protected against Covid-19, including the currently circulating Omicron strain (to a certain extent) and this is done to get a better data tabulation of severe cases and the true impact of Omicron to our healthcare (such as in terms of Intensive Care Unit, bed and ventilator usage)."

Public health expert and epidemiologist Datuk Dr Zainal Ariffin Omar said although Covid-19 was a threat to infants and children, the majority of cases were reported to be mild.

"But, statistics on this is still limited due to the small cohort and shorter time of observation.

"While we await Pfizer's study on child vaccination, parents should take precaution and preventive measures for their children through other public health measures, such as avoiding crowds, ensuring good ventilation and nutrition."