More children are in hospital with Covid - why is this?

There has been a sharp rise in the number of children testing positive for Covid in hospital - an epidemic curve that looks scary. But what do we know?

The first thing to remember is when there’s more of the virus around, the number of people in hospital with it is likely to increase - and that includes children.

But that doesn’t necessarily mean they’re much sicker.

It might be that someone happens to test positive for Covid (because there’s lots around, that’s more likely to happen) but has come to hospital for other reasons.

Prof Russell Viner, a paediatrician at the Institute of Child Health, says that between 6-8% of children have Covid, so this essentially means that around one in 12 children in any admission has a chance of being positive.

"Despite the rise, the clinical data is reassuring,” he says.

But there are some differences from previous waves.

Government data show that hospitalisations have risen in 6-17 year olds - but only marginally compared to case increases.

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The biggest increase is in the under 5s. Until recently these numbers were fairly evenly split.

So what’s happening? Very early data from a large sample of hospitals across the country (ISARIC4C) published today analyses what we know so far about the children taken into hospital.

The biggest proportion of children in hospital are babies under 1.

Prof Calum Semple, a paediatrician and one of the lead researchers, says it’s this that’s driving the increase.

Prof Semple says that while going into hospital is incredibly stressful for any parent, “these are not particularly sick infants,” he says.

“They’re coming in for a short time for investigations.”

These early data also show what they’re seeing in a hospital is slightly different.

The percentage of children in hospital testing positive for Covid needing oxygen therapy; going into intensive care; or needing ventilation has progressively dropped across waves - and is now lower than at any other point.

But these are still early data and may change over time. It’s too early to draw conclusions.

Prof Viner Russell says this is more like the typical winter respiratory illnesses they’re used to seeing.

In past waves, the majority of children in hospital with Covid had comorbidities - or other illnesses. That doesn’t seem to be the case at the moment, he says.

Although they are early data, what they’re seeing so far suggests that babies with other medical conditions don’t seem to be at higher risk.

Doctor Camilla Kingdon, a neonatologist who works with the sickest babies, says they do not want to make light of children coming in with Covid.

She says that the mothers and babies that she has seen that have had Omicron have maybe been a little bit “off their feeds” or had “low grade fever”. But none had come to significant harm.

She says paediatricians thought there’d be a tough winter. Young people have been at home and not exposed to viruses. This would inevitably change when they started to mix again.

But if that’s the case why are the under ones driving the increase in hospital admissions? Again these are very early data and researchers are still working out what we’re seeing.

Dr Alasdair Munro, a paediatric infectious diseases doctor, also suggests that this picture may also reflect who has some kind of immunity.

The majority of children over the age of 5 have either been infected previously, have been immunised, or both. The group with the lowest rate of immunity is children under 5, and in particular, children under the age of 1 year, he says.

“Given the extraordinary recent rates of infection in age groups who are likely to be parents to young children, we are seeing higher case numbers in that age group which is resulting in higher rates of hospitalisation,” he says.

And there’s something else that may be at play. There are different guidelines about when to admit someone to hospital.

The most common symptoms were cough and fever. Prof Viner says we’re much more cautious with babies - the threshold for admitting them is lower.

The NHS in England has guidelines about when a baby with a fever should be admitted to hospital and doctors are even more cautious with a baby under three months.

Overall, while these are early data and the picture may change Dr Kingdon said what they’re seeing so far is “very reassuring”.