The rollout of COVID-19 vaccines for Australian children aged five to 11 officially got underway this week, but not without a few hiccups.
On Monday, many parents were left frustrated and scrambling to find new appointments for their children after vaccine supply issues triggered widespread, last-minute cancellations.
Health authorities have urged parents not to panic, saying there are enough supplies for all eligible children to receive a first dose by the end of the month.
But the recommended eight-week interval between Pfizer's two-dose paediatric vaccine means primary school children will head back into the classroom only partially vaccinated, if at all.
So, what are the risks of the now-dominant Omicron variant for kids?
Is Omicron less severe?
So far, evidence suggests Omicron infections more often result in mild illness compared to earlier variants of the coronavirus.
At an individual level, Omicron appears less likely to put you in the hospital or ICU, especially if you're vaccinated.
While scientists are still learning about how the new variant affects children, paediatric infectious disease specialist Asha Bowen says it's clear that COVID-19 infections continue to be mild in the vast majority of kids.
"On the whole, most children are either asymptomatic or have a very mild illness, which may include a runny nose, some fevers, or feeling unwell for a couple of days," said Dr Bowen of the Telethon Kids Institute.
"[Children] bounce back relatively quickly … and the majority do not need medical or hospital-level care."
Throughout the pandemic, children have been less likely to become sick with COVID-19, compared with adults.
Preliminary data recently released by researchers at the Sydney Children's Hospital Network found that during last year's Delta outbreak in NSW, one in five children under the age of 16 had no symptoms at all.
Of the more than 17,400 children infected with COVID-19 between June and October in NSW, 1.26 per cent were admitted to hospital for medical reasons. Of those, 93 per cent did not require oxygen support.
"We know that when kids have been admitted to hospital, the average length of stay is about two days," said Dr Bowen.
"They're not staying for a long period of time, and they're not requiring a high level of intervention."
Other preliminary data published by US scientists earlier this month shows that since the arrival of Omicron, the risk of hospitalisation in children under the age of five has fallen to one third of what it was during the peak of Delta.
Researchers observed a similar reduction in the risk of severe illness in children aged 5-11 and 12-17, according to paediatrician Margie Danchin from the Royal Children's Hospital in Melbourne.
"What they've shown across all the age groups is that kids are about 50 to 60 per cent less likely to be admitted to hospital with Omicron compared to Delta," said Dr Danchin, who is also a vaccine researcher at the Murdoch Children's Research Institute.
"Having said that, the data only goes up to December 24 and this is an evolving situation, so we need to watch it really closely."
As Omicron surges, will more kids be hospitalised?
While Omicron causes less severe disease on average, it also spreads much faster than any other variant. As a result, more people, including children, are becoming infected.
"Because of the sheer high numbers, there are more children in hospital," Dr Bowen said.
"But they are still a very small proportion [of overall cases]."
Both Dr Bowen and Dr Danchin stressed there was no sign that paediatric hospitalisations in Australia had increased substantially.
Infectious diseases paediatrician Robert Booy agreed, and said it was adult hospitalisations putting pressure on the healthcare system.
"Although [paediatric] hospitalisations are increasing, they are not increasing to a worrying level," said Professor Booy of the University of Sydney.
"They are increasing commensurate with the level of exposure and transmission."
Overseas, hospital admission rates of children and teens have risen in recent weeks, but remain lower than that of any other age group.
The increase is likely to be explained, at least in part, by the sheer contagiousness of the Omicron variant, with more children becoming infected overall.
But experts say the rise may also be due to more children being admitted to hospital for other reasons and then incidentally testing positive for COVID-19 during routine screening.
Dr Danchin said it was also important to recognise that sometimes children were admitted to hospital for non-medical reasons, such as having family members who were too unwell to care for them.
What about very young children?
In the United States, data shows hospital admissions of children aged under five years has doubled since mid-December — a jump that hasn't been seen in other younger age groups. A similar trend has been observed in the UK.
These children are the only age group not yet eligible for a COVID-19 vaccine.
In a recent news briefing, Centers for Disease Control and Prevention (CDC) director Rochelle Walenksy said the trend in children too young to be vaccinated underscored the need for older children and adults to get their shots to help protect those around them.
But she noted there was no evidence of any increased severity associated with Omicron in children under five.
Dr Danchin said doctors were more likely to admit very young children with viral infections out of caution, to ensure they were feeding well and properly hydrated.
Dr Bowen added that the spread of other respiratory infections, such as the flu, could be leading to increased hospitalisations.
"I think because we're in the summer months, we're not seeing that intersection of more than one respiratory virus at the same time," she said.
"Whereas in the US and UK, it's winter, so respiratory virus season … and that could alter the way in which their case numbers are being impacted."
The benefits of vaccination
Though COVID-19 appears to be mild in the vast majority of kids, vaccinating those who are eligible has two benefits: it helps to protect other vulnerable groups, and reduces children's own risk of severe disease.
This is especially important for children with underlying medical conditions, Professor Booy says.
Current evidence suggests children with complex genetic, neurological or metabolic conditions, as well as those with heart or lung disease, are at increased risk of severe COVID-19.
And similar to adults, children with obesity, diabetes or severe asthma may also be at increased risk.
"It's really important where there are children with a major medical problem — Down's syndrome, cerebral palsy — or chronic medical issues … [they] need to be at the front of the queue to get vaccinated," Professor Booy said.
"Their second dose will be really important for their protection."
For the majority of children, Professor Booy said one vaccine dose was likely to offer "very high levels of protection".
Research shows vaccination also helps to protect children against a serious but rare COVID-19-linked condition that involves inflammation of multiple organs.
Multi-system inflammatory syndrome causes symptoms such as persistent fever, abdominal pain and rashes.
"About one in 3,000 children get multi-system inflammatory syndrome, which kicks in two to three weeks after COVID," Professor Booy said.
"Most children recover from that, but there are rare cases of death.
"[Research] shows that if you're vaccinated, there is 90 per cent protection against it."
