As New Zealand battles the Delta variant of Covid-19, increasing numbers of children around the world are catching the virus. Sam Sachdeva investigates calls for better school ventilation and parental sick leave provisions to protect this country's young.
Throughout the Covid-19 pandemic, much of the focus has gone on how to protect our most vulnerable elderly population against the deadly virus.
That remains the case, but focus is starting to shift to how Covid might affect the youngest generations.
In our current Delta outbreak, there are now seven schools where either students or staff have tested positive, while 28.4 percent of the 116 active cases in New Zealand are people aged between zero and 19 – double their representation among all the country’s cases since Covid-19 first reached our shores (14.2 percent).
Other countries are also seeing children make up a growing proportion of new Covid-19 cases: in the UK, infection rates are surging for children between 10 and 19, while 43 percent of Canberra’s cases as of August 20 were in under-17s.
Director-General of Health Ashley Bloomfield says the potential vulnerability of young people to the Delta variant is an added incentive for New Zealanders to get vaccinated, given the current inability of those under 12 to receive that type of protection.
“It does seem Delta is having a bigger impact on younger people, and that’s all the more reason why we need to all just act to get rid of it out of our community at the moment to keep our young people and children safe,” Bloomfield says.
But why is the virus having a bigger impact now, and what should we be doing to guard against it?
“Because Delta’s very, very transmissible, if you have a large proportion of the population infected all at once, you should expect to see a surge of cases in children just because of it." – Dr Jin Russell, University of Auckland
Dr Amanda Kvalsvig, an epidemiologist at the University of Otago in Wellington, cautioned against drawing too many conclusions from the age spread early in an outbreak, as identified infections would be skewed by the close contacts of early cases.
Kvalsvig said the number of young people infected in last year’s main outbreak may also have been underestimated, given children weren’t tested at the same rate as adults.
But even with those caveats in mind, “we can still say that other places experiencing Delta outbreaks are seeing a large number of child cases" – a cause for concern for Aotearoa, with high health inequalities in our child population and many children with underlying conditions and at risk of serious illness.
Dr Jin Russell, a developmental paediatrician and PhD student in child epidemiology at the University of Auckland, told Newsroom the growing number of Covid cases among children appeared to be less of a particular vulnerability to the Delta variant and more about its higher rates of infection across all age groups.
“Because Delta’s very, very transmissible, if you have a large proportion of the population infected all at once, you should expect to see a surge of cases in children just because of it.
“And when you see a surge of infections in children, we usually expect to see a proportion of those children falling sick and needing hospitalisation.”
Another factor at play is the simple fact of children’s ability – or inability, to be more precise – to be vaccinated against Covid-19.
While the Government last week announced it had authorised the use of the Pfizer vaccine for 12- to 15-year-olds, other countries have only allowed access to at-risk children in that age group, and there is currently no vaccine which has been approved for children under 12.
With vaccination rates growing around the world and offering adults protection against infection, it was unsurprising that children would start to make up a greater proportion of new Covid cases, Russell said.
Although children are at lower risk than adults of suffering serious illness or death from Covid-19, some do end up in hospital – particularly children who have pre-existing conditions such as obesity, respiratory disease and neurological or immune disorders.
A meta-analysis of international Covid-19 research completed in February found just over five percent of children with so-called “comorbidities” suffered from severe illness when they caught the virus, compared to just 0.2 percent without underlying conditions.
Russell said there weren’t yet any reliable estimates for paediatric hospitalisation rates associated with the Delta variant.
However, some calculations suggested a similar hospitalisation rate in New Zealand to that of the US would lead to four children being admitted to hospital daily, and one a day to intensive care – numbers which would quickly overwhelm the country’s health system, given Auckland’s Starship Hospital houses our only dedicated paediatric intensive care facility.
That strain would be further exacerbated should a rise in paediatric Covid cases coincide with a spike in other illnesses which particularly affect children, such as the recent outbreak of respiratory syncytial virus (RSV).
“If we were, say, to accept an endemic or seasonal surge of Covid every winter...on top of our current surges of influenza and RSV and other respiratory viruses, I think there would be a lot of strain on our hospitals,” Russell said.
Keeping Kiwi kids safe
So what can be done to reduce the risk to children, and to the country as a whole?
“Prevention is the answer,” said Kvalsvig. Kiwi kids needed to experience “a completely different standard of air quality” once they moved out of lockdown and back to school.
“There’s abundant evidence now that outbreaks in the school setting can largely be prevented by taking action to stop airborne transmission.
"Key measures include ventilation – which may be a sophisticated ventilation system, or it may be as simple as opening a window or taking an activity outdoors – filtration of indoor air to remove virus particles, use of masks, and managing the number of children in a room and the amount of time they spend there.”
Evidence that very young children tended to transmit Covid-19 to their caregivers, and adolescents to theory peers, could also shape both vaccine strategies and other prevention measures – such as paid sick leave for parents to keep children home from school or daycare when they were unwell, to stop transmission routes.
The vulnerability of children to the Delta variant, and to Covid-19 more generally, could also prove a pothole in the way of the Government’s “roadmap” to reopen our borders.
According to modelling recently published in The Lancet, New Zealand could only reach the threshold for herd immunity against the original strain of the virus if 86.5 percent of the population was vaccinated – a figure which rose to 98.1 percent against the more infectious Delta variant.
“It's difficult to imagine opening the borders without having at least tried to vaccinate children."
Neither target would be achievable if zero- to 11-year-olds remained off-limits for vaccinators, with a maximum coverage of 84.9 percent.
“It's difficult to imagine opening the borders without having at least tried to vaccinate children,” Russell said.
“There's a reason why, for other vaccine-preventable diseases, we vaccinate children: because they're cohorted together in schools, and they basically are a reservoir for the virus to be circulating.”
Good news on the vaccine front may be around the corner, with clinical trials underway: according to The Atlantic, Pfizer has indicated it will make an emergency use application in the US for five- to 11-year-olds by the end of September, and for six-month- to five-year-olds shortly afterwards.
But the Government could not rely on vaccines alone to reconnect safely with the rest of the world, Kvalsvig said, even if high vaccination rates for children would help to reduce risk and prevent outbreaks.
“It’ll need to be multi-layered, combining vaccines and other measures, including, importantly, much more attention to preventing airborne spread of virus in public spaces.”
