Since the turn of the new year, daily child hospitalisation rates have risen to record-high levels. Although they are incomparable with admission rates for adults, almost as many children have been taken to hospital in the first nine days of 2022 (1,098) as the entirety of the first wave (1,333).
But, as has been the case from day one, there’s more to the data than meets the eye. The children going to A&E are less sick than they have been at any stage of the pandemic, dismissing theories that Omicron is more severe in young people.
The proportion of hospitalised children requiring oxygen has fallen too. Between 14 December and 12 January, only 12 per cent of under-ones were given oxygen, down from 20 per cent in the Delta wave.
The number being moved to intensive care has similarly decreased over time, while the average amount of time a child of any age spends in hospital is also down. At the beginning of the pandemic, 12- to 17-year-olds were typically hospitalised for 11.5 days. Now, it’s 2.5 days.
“I really want to emphasise the fact that these are not particularly sick infants,” said Calum Semple, a professor of child health at the University of Liverpool. Dr Camilla Kingdon, president of the Royal College of Paediatrics and Child Health, said those “on the shop floor” were not “picking up any signals that are overly concerning”.
The data comes from the Isaric study, led by Prof Semple, and is drawn from half of all NHS hospitals, making it “broadly representative” of the national picture, he said.
Some experts have speculated that the high prevalence of infections in the UK – which have reached previously unseen levels recently – is playing a key role in the recent uptick in admissions.
With more virus around, it’s to be expected that more children catch Covid and fall ill. Incidental admissions – those who are taken to hospital for other issues but test positive – are also going to be on the rise due to the Omicron wave, though data on this is light.
Due to the current high rates among young people, “around one in 12 of any admission into hospital, whether it’s with a broken leg or appendicitis or any reason at all, has the chance of being [Covid] positive,” said Russell Viner, a professor of child and adolescent health at University College London.
But the high prevalence theory doesn’t fully account for the fact that the recent rise in admissions isn’t consistent across all age groups. Instead, it is being driven by infants.
The majority of children hospitalised in December and January were under 12 months old – 171 out of 405, or 42.2 per cent. As a proportion, this is up significantly from previous waves, when roughly 30 per cent of paediatric admissions were among the under-ones.
More children from the poorest areas of the UK are now also being taken to hospital, compared to earlier in the pandemic. Those from the most deprived fifth of households account for almost half of admissions, the data shows.
“This is seen across all ages and is likely reflecting lower vaccination rates in teens from deprived areas, more exposure to infection and higher rates of other health conditions making them more vulnerable to severe illness once infected,” said Professor Christina Pagel, director of the clinical operational research unit at University College London.
One hypothesis about the child hospitalisation rate is that the high transmissibility of Omicron has allowed it to succeed where other variants have failed: in reaching tiny pockets of the population that have yet to develop immunity to Covid. In other words, newborn babies.
“The group with the lowest rate of immunity is children under five, and in particular, children under the age of one year,” said Dr Alasdair Munro, a clinical research fellow in paediatric infectious diseases at the University of Southampton. “This means we would expect a larger proportion of admissions to be among this population, which is what is demonstrated in this data.”
Others have theorised that Omicron’s apparent preference for replicating higher up in the airway, which is smaller and not as developed in infants, means it’s causing this age group the type of respiratory difficulties that are typically seen with annual winter infections.
“There’s potentially some evidence that this variant of the virus is affecting the upper airways more than previous variants,” said Dr Viner. However, he added, “I think we need to be careful in suggesting that it’s all down to that”.
In terms of children requiring brief hospital care for fevers and coughs, “I think we’re seeing Covid behaving a bit more like the normal winter viruses in children,” said Dr Viner.
Data shared by Dr Munro shows that around 15,000 children aged 17 and under have been hospitalised for Covid-19 since the beginning of the pandemic. In comparison, annual child admissions for viral wheeze, bronchiolitis and ear infection stand at 77,488, 51,655 and 33,000 respectively.
“As paediatricians, we are accustomed to having busy winters where we see lots of particularly under ones, typically with high fevers, often with some kinds of respiratory distress, increased work of breathing, cough, poor feeding. The pattern this winter is very, very similar,” said Dr Kingdon.
But still, the current clinical picture is “incredibly reassuring”, as Dr Viner said, reinforcing the belief that the virus poses only a minor risk to the vast majority of children.