How does COVID-19 affect children?

September 1, 2021

In our latest expert webinar, Professor Tim Spector, lead scientist at the ZOE COVID Study, was joined by Emma Duncan, professor of clinical endocrinology at King’s College London, and Dr Michael Absoud, a consultant in paediatric neurodisability and Honorary Reader at the Department of Women & Children’s Health also at King’s College London.

They discussed how seriously COVID affects children, the risks of long COVID, and whether we should be vaccinating kids.

How does COVID-19 affect children?

Back in June and July this year, the current wave of COVID-19 was mainly being driven by people in the 18-35 year old age bracket (orange line in the graph below). However, while cases in that group have fallen, we are now seeing a concerning rise in children (dark blue line).

According to our estimates based on data from the ZOE COVID Study, around 14,000 children are getting COVID-19 every day across the UK. And we’re seeing these rates go up even faster in Scotland where schools have already gone back after the summer break.

Graph showing COVID-19 incidence by age


What is COVID like in children?

According to Emma, the most common symptoms of COVID-19 in children are actually no symptoms at all, with asymptomatic infections being common.

“On average of those who catch the virus, somewhere between 40% and 70% of kids don’t have any symptoms at all,” she says.

“In the study we’ve just done of people who did report symptoms in children using the ZOE COVID Study app, the most common are fever and headache, then persistent cough, sore throat and so forth.”

The prevalence of certain symptoms depends on the child’s age. For example, tummy pain is a common symptom in younger kids that doesn’t occur so often in older children, while older children are more likely to suffer loss of smell (anosmia).

The wide range of symptoms - many of which overlap with other common infections - can make it difficult to tell the difference between COVID-19 and any of the other myriad illnesses that children can pick up. 

“Not every stuffy nose is COVID,” Emma explains. “The biggest difference we saw was in the length of illness - children with confirmed symptomatic COVID are ill for around 6 days, whereas those who were sick with something else were ill for an average of three days.”

How likely are children to be hospitalised with COVID-19?

Fortunately, most COVID infections in children are mild and the chances of becoming seriously ill or ending up in hospital are very low. So even though the majority of infections are now in younger adults and children, the proportion of hospitalisations and deaths is far higher in older age groups.

“Nationally we saw 300-400 children in hospital across the UK in the first wave back in early 2020,” says MIchael. “We’re not seeing it yet with Delta, but it may come.” 

However, given the high rates of symptomatic COVID among children at the moment, that could still mean 20 to 30 children admitted to hospital with the diseases every day across the country. 

Tim points out that it’s important to keep this in perspective and not to worry unduly.

“It’s still very, very unlikely that if your child does get COVID that they’re going to end up in hospital,” he says.

Michael adds, “Most of the children who do get admitted to hospital do thankfully have a good recovery. 24 children sadly passed away in the first wave of the pandemic, but many of them had comorbidities that put them at much higher risk.”

These high risk health conditions include neurological conditions, severe learning disabilities, and some genetic disorders such as Down syndrome. Children who are immunosuppressed, either as a result of a health condition or due to medication, are also at increased risk from COVID-19.

Reassuringly, Emma and her team haven’t discovered an increased risk of falling seriously ill with COVID-19 in children with asthma, unlike the situation in adults

Are children at risk of long COVID?

Many parents are concerned about the risks to their child from long COVID. However, there is good news here. 

While we’ve shown that up to 1 in 7 adults experienced COVID-19 symptoms for more than four weeks and 1 in 20 suffered from symptoms for more than eight weeks, the story is very different for kids. 

“If you’re looking at prolonged duration of symptoms, around 4.5 % of children who have symptomatic disease will have symptoms that last for 4 weeks, but if you go to 8 weeks it’s down to around 1.5%,” Emma says, highlighting data gathered from the ZOE COVID Study app

This works out at around 1 in 70 to 1 in 100 children with COVID-19 who show any symptoms at all are likely to suffer for many weeks, while around half or more who catch the virus will never have any symptoms at all.

“People get sick for others reasons than COVID,” she adds “The proportion of children ill with other things that went on to have symptoms at 4 and 8 weeks was less than those children who were sick with COVID, but those who were sick at 4 weeks with other illnesses had a much more burdensome course of disease.”

Should children be vaccinated against COVID-19?

Right now, around three quarters of UK adults are fully vaccinated, which is likely to have prevented many tens of thousands of deaths from COVID-19. Currently vaccination has been extended to children aged 16-17 and those who are younger with serious underlying health conditions or who live with someone at high risk.

However, the balance of risks against benefits from vaccination changes in younger age groups. Children have a much lower chance of becoming seriously ill, being hospitalised or dying from COVID-19. But while the vaccines are extremely safe and well-tested, there is a very small increased risk of inflammation of the heart (myocarditis) in children following the Pfizer vaccine.

“We’re going to need these vaccines for a long time - probably for the rest of our lives and our children’s lives - so the safety has to be really robust,” says Michael. 

“We need to balance between the benefit for the community against the risk to the individual for any vaccine,” Emma explains. “My understanding is that the benefits will outweigh any potential risk to the child, but we’ll be looking at this through the ZOE COVID Study as soon as we have enough data.”

Whatever happens, it’s highly unlikely that very young children will be getting a COVID vaccine any time soon, putting the burden on anxious parents to protect their kids.

“One of the most important things that we can do to help protect toddlers is to get everybody else vaccinated, because that will make things safer for everyone,” Emma says. 

“That’s particularly important for parents of young children, women who are pregnant, planning to become pregnant or recently been pregnant, and breastfeeding mothers as well, because if they are vaccinated their chance of bringing it home and giving it to their child goes down substantially.”

It’s important to remember that there are many other infectious diseases in the world other than COVID-19. We’re currently seeing a drop in other routine vaccinations that protect against serious or even fatal childhood diseases such as measles, mumps, rubella,  tetanus, diphtheria and polio, putting children and those who are vulnerable in the wider community at risk.

Finally, there’s a discussion that needs to be had about how best to use vaccines to benefit the most people.

“Vaccines are a finite resource,” says Tim. “There’s a rise in hospitalisations and waning of the vaccine in adults, leading to talk about having to give vaccine boosters by the end of the year.”

Vaccinating a wider range of children and giving boosters to the elderly, vulnerable and healthcare workers may not be possible with the supply we currently have guaranteed. 

As a solution, Tim suggests doing antibody testing on children first, to see if they have existing immunity from being infected with the virus and are therefore probably OK without a vaccine compared with those who don’t have antibodies and may benefit from vaccine protection.

Furthermore, the question of who should be at the front of the queue for vaccination is a global issue.

“If we’re not vaccinating adults in other countries then the pandemic is going to carry on,” Michael says. “We need to get the vulnerable vaccinated, not just in a single country but globally.”

How is COVID harming children?

The COVID-19 pandemic has had a bigger impact on child health and wellbeing than just the disease itself.

“The main harms that have happened to children have not been directly from COVID but been indirect,” explains Michael. “Having multiple repeated isolations of ten days to two weeks is particularly harmful for many different reasons. There’s disruption to education and even the anticipatory anxiety of knowing that you’ll be isolated soon has been quite harmful for kids. As paediatricians we’ve seen a rise in mental health conditions, and it’s affected those with disability, SEN (special educational needs) and deprived communities a lot more than the well-off middle classes.”

“For most adults, this has been one of the more frightening and distressing times of our lives - this new thing has arrived and we’ve had to adapt quickly, with changes around the world, distancing, and not being able to see family and friends,” Emma adds. “In adults, it’s been very tough and I can’t imagine how much harder it is if you were five years old, particularly if you’ve had members of your family sick, in hospital or even lost them.” 

“It’s the children living in deprived communities and those with special educational needs - they’re the ones who have been hit hardest by the pandemic,” Michael says. 

“I’m hoping that policymakers will think about this in terms of the future generation - that’s how you improve health in general: by reducing those inequalities, not just thinking about one virus.”

Every day there’s vital information coming in from our million-strong ZOE COVID Study app community, helping us to understand the impact of the pandemic and vaccination in adults and children. 

We need as many people as possible of all ages to download the ZOE COVID Study app, log your vaccines and do a daily health report. It only takes a minute, but you’ll be contributing to life-saving research. 

Stay safe and keep logging.

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