Herd immunity: COVID-19 vaccines for kids

As levels of coronavirus infection continue to fall in the UK, and the number of people vaccinated continues to climb, the government announced this week they’re now considering widening the scope of the vaccine programme to include children aged 12 and up. The aim, they say, is to try to head off an autumn surge in Covid cases when the schools go back in September. A similar strategy is playing out in the US, and Chris Smith caught up with University of Wisconsin – Madison paediatrician and vaccine specialist James Conway, to consider this and the wider issues concerning the vaccine programme…

James - Current data that's been emerging as each company has moved into the younger and younger groups shows that these vaccines are very protective. And I don't think that's any surprise. I think we've seen that they're quite protective in older individuals as well, and so we anticipate in kids - where the immune system is even that much more robust - that they're going to have even a better and more protective response than the older individuals.

Chris - Why do you think, then, that when they were doing the trials - that they didn't include children? I mean, is that a standard approach when developing a new medicine - we just don't test medicines on kids?

James - Well in general that's true, although I think that each disease has a particular age focus. If you think about many of the other routine paediatric vaccines that we use for children, many of those are diseases that actually primarily affect kids. And so by definition then, the trials have to start out in those age groups. For this particular disease - COVID-19 - obviously the primary groups were the elderly, and then people with comorbidities. And so all of the companies appropriately were directed to really put their attention and their efforts into those groups first. In the beginning we thought the kids were relatively spared, but I think that was partially because we were so successful at protecting them by bubbling and keeping them out of school and things. Now that people are starting to loosen up activities, we're starting to recognise that kids actually can be transmitters, and can even be drivers of outbreaks.

Chris - Critically, though, they are at really, really low risk from severe coronavirus manifestations, aren't they? One of our Deputy Chief Medical Officers quite famously last year said, "quite frankly, a child is at greater risk from being run over by the school bus than they are from a dose of coronavirus infection". But what that means is that some parents have turned this round and they're saying: given the low risk to children from disease, the vaccine actually - albeit with rare side effects - potentially poses a greater threat than the disease does.

James - Well I think that that represents something of a false narrative. Low risk doesn't mean no risk. And so there've been hundreds of children who have died unnecessarily from this disease. And we recognise that every life is valuable, and so I think there is a major moral imperative to try to protect all individuals that could suffer from this disease. But the secondary gain, then, is also that public health measure of then starting to be able to eradicate ongoing circulation by achieving higher and higher rates of community immunity, or what some people call herd immunity.

Chris - And is that the approach being taken in the US as well?

James - Yeah, the approach here in the US was initially to do individuals over age 65, and then healthcare workers, then moving into younger populations, and then more recently now moving into high school aged, and then eventually middle school aged children. Within the next few weeks we think there will be approval of vaccines into those populations.

Chris - Looking across the world now, with your 'global vaccine' hat on, how do you see all this playing out? Because what is hitting the headlines a lot at the moment is the question of what rich countries are doing versus what poorer countries are doing.

James - We will never eradicate any disease without reaching every child and reaching every corner of the world. And so I think it has been a little bit of a blind spot for many of the richer countries to focus internally - which, granted, from a political standpoint is what their pressure is going to be - but they will never be able to get back to any degree of normalcy with global trade and global travel until we also start to stamp out circulation around the globe. And so I think that there really has to be, and is finally starting to be, a lot more attention on a collaborative approach to try to make both funds and vaccines available. But the other piece, though, is that vaccine hesitancy is real. There's certainly been a lot of tension around certain countries being more willing and eager to vaccinate, and how those vaccines get distributed equitably within those countries.

Chris - Of course that was a worry in America before all this began, wasn't it? Studies last year were suggesting that maybe as many as half of Americans would turn down a vaccine if offered it the next day. That has changed, though, because we saw a similar kind of ‘uptick in uptake’ in the UK.

James - Yeah, it's been interesting, because of the half that were a little bit hesitant... we've seen a substantial number of that population shift over into being more willing. And then what we've seen is really an entrenchment of about 20% of the population who have really dug in their heels and said that, for whatever reason, whether it's COVID complacency, or COVID denialism, or whether it's with other political reasoning... that there are about 20% of the people that are just flat out refusing, for various reasons, to be vaccinated. And so it does raise the spectre: will we actually be able to get to the point of herd immunity at a high enough rate that the ongoing transmission could completely be eradicated? And so what we're starting to realise and starting to worry about is that if we see that manifest itself globally, this becomes then like influenza and many other respiratory viruses - something that just continues to circulate in the background and serve as an ongoing threat, especially to those with underlying medical issues.

Chris - Is that not likely to be the case anyway?

James - Well - except that there is something of a defeatist view in that kind of a mindset. Because here in the United States, only about 40-45% of the population gets a flu vaccine in any given year. There's no mandates, and really very few requirements, except for some limited professions and areas of the country. And so we still deal with hundreds of thousands of hospitalisations and 20, 30, 40 million cases a year, lots of lost time from work and lost time from school, and 20, 30, 40, 50 thousand deaths a year in bad years. And it's been somewhat saddening to me as a public health leader to realise that people have been willing to accept that kind of defeatist mentality. We've defeated and eradicated a handful of diseases from the face of the earth - smallpox, and some types of polio - and we did that by a concerted global effort to achieve high herd immunity rates across the globe. And we have that capacity. We've clearly shown historically that we can do that. But it takes a concerted, organised effort. And the hope and the dream is that, in some manner, we can figure out a way to incentivise immunisation so that the larger portion of the population does accept these things, and maybe we can actually get rid of ongoing circulation and outbreaks of these diseases.