A Covid-19 vaccine for Kiwi kids under five is unlikely to arrive before our Omicron wave peaks, an expert says - but it's being stressed these youngest children remained at low risk of severe sickness.
Pfizer and its pharmaceutical partner BioNTech this week announced they'd submitted authorisation of a two-dose regimen for children aged 6 months to 5 years to the Food and Drug Administration (FDA) – which unusually came at the request of the US regulator itself.
The companies planned to soon file additional data supporting a three-dose programme – something regulators encouraged after the two-dose course was last year shown to be less effective at preventing the virus in kids aged 2 to 5.
Pfizer believed three doses of the shot, which carried one-tenth the strength of the adult vaccine, would be needed to achieve high levels of protection against current and future variants – but clearance of a two-dose series would help a US rollout get underway in the meantime.
There, more than 10.6 million children have tested positive for Covid-19, with children under 4 years old accounting for around 1.6 million of them.
Amid the Omicron surge, doctors had observed a notable spike among child cases, and those under 4 made up around 3.2 per cent of total hospitalisations as at January 22.
NPR reported that the regulatory process in the US – beginning with the FDA submission and ending with the US Centers for Disease Control and Prevention signing off – could take just weeks, as it did with the emergency application for kids aged 5 to 11.
Otago University epidemiologist Michael Baker said that didn't mean Kiwi parents could expect a vaccine for under-5s to arrive here that quickly.
That was because the vaccine, if approved in the US, would need to go through the extra step of MedSafe assessment and approval here, while distribution arrangements would also need to be arranged.
While the vaccine for 5-11-year-olds was approved by the US in late October, MedSafe didn't give provisional approval here until mid-December.
"So, it's quite likely that it will go through the approval process here, but I wouldn't think it's an option for parents that will arrive very soon."
A Ministry of Health spokesperson said if an application was received from Pfizer in the future, it would be assessed as a priority.
In the short-term, Baker expected much of our logistical capacity would be taken up by rolling out the booster in the face of a building Omicron outbreak, and completing the child vaccine rollout.
"By then, hopefully we'll be in a position where we would have slowed Omicron down slightly, and some of the urgency for vaccinating very young children now will have disappeared," he said.
"But fundamentally, I don't know how we can really anticipate the net effect of a lot of these vaccination decisions on the long-term relationship that we're going to have with this coronavirus."
While there were still many unanswered questions about how we might build up Covid-19 immunity in the long-run, and what challenges new variants might bring, he felt it was important to have the population as well protected as possible.
"So, my default option would be to vaccinate everyone who consents, as fast as we can."
In a commentary last week, Baker and colleagues noted the great majority of our children were "immunologically naive" to Covid-19, suggesting that the impact on children may be even more marked here than in other places.
Alongside shortening the vaccine dose interval for 5-11-year-olds from eight to three weeks, the researchers also recommended distributing masks to children aged over 2.
But Professor Peter McIntyre, an Otago University paediatrician and immunisation expert who serves as Immunisation Advisory Centre medical adviser, believes there is a risk of misunderstanding among parents and the general public that vaccinating young children would drive down total infections.
"The thing which needs to be emphasised is that, while young children have the lowest risk of severe disease of any age group, there are a small but important number of children who unfortunately get severely ill with the virus," he said.
"In our new environment of high adult coverage, we need to have the mindset of, 'how do we protect our kids from getting severely ill', rather than thinking "if we rapidly give all kids vaccines that's going to have a major impact on total infections."
McIntyre, a member of the World Health Organisation's Strategic Advisory Group of Experts, added the latest child vaccine wouldn't address the risk of babies under six months being infected.
Infants were a major part of cases under five years, both in the US and closer to home in the Delta outbreak in New South Wales.
"To do anything about these children we're probably talking about their mums getting vaccinated," he said.
"It starts to become a discussion more like influenza, than like Covid-19 in 2020.
"Where is this going to end up? When we're a few years down the track and we'll obviously have Covid still around, and we'll have kids being born who haven't had the virus before, how much of a problem is that going to be?
"Will we need to look at the Covid vaccine being added to pertussis and flu in pregnancy to protect young babies?
"But ultimately, I think we can say that, for the great majority of otherwise healthy young kids, Covid is likely to end up being like other respiratory viruses that can put young babies with small airways in hospital in a way that doesn't happen when with older kids."
In the meantime, the ministry said parents of children under five were encouraged to get vaccinated themselves and to limit interaction with unvaccinated people to reduce exposure for unvaccinated children.
Breastfeeding parents could also get the Pfizer vaccine at any time, the ministry said.
"Studies show there are no additional safety concerns or issues with continuing to breastfeed after vaccination.
"If you are vaccinated against Covid-19, there is evidence that you can provide extra protection for your baby through antibodies in your breastmilk."