THROUGHOUT the pandemic we have seen considerable debate around the role of children in transmission of SARS-CoV-2. Nowhere has the debate about children been more fiery than around school closures.

In Melbourne, during the current outbreak, several schools have been closed following a student testing positive at one school and a staff member at another. Some argue against school closures, or to use this only as a last resort, citing harm to education and socialisation, and logistical problems for parents and guardians.

Yet in Israel, as adult vaccination rates rose, an increase in childhood infections was noted, with the Alpha variant (formerly named the UK B.117) more likely to transmit in children than the previous D614G strain.. SARS-CoV-2 infection in children is not trivial, with 2.5% hospitalised and a  case fatality rate of less than 0.1 (over 600 deaths in 2.8 milion cases). It is estimated more than 7% of children aged 2–11 years who contract SARS-CoV-2 will develop longCOVID. Another study found over half of children 6–16 years old with COVID-19 had at least one symptom lasting more than 4 months, with 42.6% suffering impairment of daily activities.

When considering the life expectancy of children, arguably they have the most to lose from persistence of the pandemic, so should be included in any vaccination program.

Valid motivations to keep children in school and the vulnerability of the older school staff and parent population to SARS-CoV-2 spread should be all the more reason for Australia to prioritise vaccination of children along with the rest of the school community.

The other reason is that with more contagious variants of concern, vaccinating children may be the only route to herd immunity, with consequent protection for the unvaccinated or those with poor immune response. Despite the nay-saying about herd immunity as a vaccination goal, it may be feasible based on scientific principles. Achieving herd immunity depends on the R0 of the virus and the level of vaccine coverage – we have achieved it for measles and poliomyelitis in Australia through vaccination, so it may well be possible for COVID-19.

For instance, we showed that for the dominant strain of SARS-CoV-2 in 2020 with an R0 of 2.5, if a vaccine with 90% efficacy against all infection is used, herd immunity can be achieved by vaccinating 66% of the population – a goal that is achievable in a likely “high vaccine uptake” country like Australia, without vaccinating children, who comprise 20% of the population. We also showed that a vaccine with less than 60% efficacy was not able to achieve herd immunity, even with 100% of people vaccinated. A study from Europe confirmed this, and also looked at scenarios where more transmissible variants such as Alpha and Delta become dominant. They show that in a country like Australia, with low infection-induced immunity in the population, if these variants dominate, we can only achieve herd immunity by vaccinating adults and children aged 15 years and over, and using a vaccine with 80% or greater efficacy against all infection.

Crucially, “all infection” includes symptomatic and asymptomatic infection, which is quite different from the high effectiveness estimates against hospitalisation and death that we usually hear about. Most clinical trials used symptomatic infection as the primary end point (and commonly cited efficacy figures refer to prevention of symptomatic infection), so it is important to understand the difference. When it comes to prevention of all infection, the AstraZeneca (ChAdOx1-S) has 22% efficacy against asymptomatic infection, whereas the effectiveness of 92% against asymptomatic infection has been reported for the Cominarty (BNT162b2[mRNA]) (Pfizer-BioNTech) vaccine. This difference may affect the likelihood of achieving herd immunity. There is a small possibility that vaccines that do not prevent asymptomatic infection as well may still result in a viral load that is too low to result in transmission – only time will tell.

As well as evidence from clinical trials, Australia can consider the real examples from other countries as we attempt to remedy a slow start to vaccination.

Some, like the US, have made determined efforts at mass vaccination and have begun vaccinating children over 12 years. In Singapore, recent outbreaks have involved adolescents, so they have prioritised vaccination of 12–18-year-olds ahead of adults aged 19–39 years. In the US, there have been reports of myocarditis and pericarditis in adolescents and young adults following receipt of mRNA vaccines, particularly after the second dose. This is rare and still being investigated, with no firm conclusion on causality yet. Israel has been vaccinating children 16 years and over, with children aged 12–15 years to follow, and consideration of a single dose for this age group. This may be a good strategy in countries where exposure to the virus has been high, as a single dose after infection provides strong boosting.

Others, like the UK, which also made a determined effort at mass vaccination of adults, are less enthusiastic about vaccination of children. Some argue that in the UK, almost a quarter of children aged 16–17 years are immune following infection (thus contributing to herd immunity through natural infection), that children are less likely to die than adults” from COVID-19”, and that they do not play a major role in transmission.

It is true that children are less likely than adults to die, with increasing age being the strongest predictor of death, especially after the age of 50 years. Younger children (under 10–15 years) are less likely than older children to transmit SARS-CoV-2, although data on infectiousness are mixed, with some studies showing lower viral load in young children and others showing higher viral load compared with adults. Yet children older than 10 years transmit the virus as much as adults, and some studies show they transmit even more than adults. An outbreak in a high school in France had a 38% attack rate among students, and in the US surges in SARS-CoV-2 transmission were noted after school reopenings. Recent evidence has emerged from India of enhanced transmission among children. COVID-19 incidence increased in children 5 to 17 years old compared with the US..

Further, underestimation of SARS-CoV-2 infection prevalence in children has been reported, so we may be underappreciating the role of children in sustaining the pandemic.

Where does that leave us?

Australia differs from most other countries in that we have very little immunity from infection in the population. In Australia, B.1617 (now called Delta and Kappa) is fast becoming the dominant variant, and Kappa is responsible for the current Victorian outbreak. The Delta variant has been estimated to be 50% more transmissible than the Alpha variant, and has some vaccine escape associated with it, especially for the COVID-19 vaccine AstraZeneca. The Kappa variant is likely to be even more vaccine-resistant due to the presence of the 484Q mutation. This is a concern, as it means outbreaks will be harder to contain, and herd immunity will be harder to attain – especially using vaccines of lower efficacy and without vaccinating children aged 12 years and over. If the potential risk of myocarditis is a barrier to vaccinating children 12–17 years, then the NVX-CoV2373 (Novavax) vaccine slated for our shores may be a good option, as the efficacy appears higher than the COVID-19 vaccine AstraZeneca., especially against vaccine-resistant variants. Just as D614G mutation took over from the original Wuhan strain and dominated transmission in 2020, it seems likely that either Alpha or Delta will take over in 2021.

The stakes have been raised with more transmissible variants, which means vaccination of children must be part of our plan and our goal should be far higher than the minimal one preventing death. For economic recovery, our best bet is herd immunity, and we will never know if we can achieve it unless we try.

Professor C Raina MacIntyre is Head of the Biosecurity Research Program at the Kirby Institute, UNSW. She is also a National Health and Medical Research Council Principal Research Fellow.

Dr Andrew J Miller is an anaesthetist with Western Anaesthesiology, and is President of the Australian Medical Association’s WA branch.

Dr Julie A McEniery is a Paediatric Intensivist at Qld Children’s Hospital, and Chair, Qld Paediatric Quality Council.



The statements or opinions expressed in this article reflect the views of the authors and do not represent the official policy of the AMA, the MJA or InSight+ unless so stated.


Children must be included in the COVID-19 vaccine rollout
  • Strongly agree (61%, 83 Votes)
  • Agree (18%, 25 Votes)
  • Strongly disagree (12%, 16 Votes)
  • Disagree (5%, 7 Votes)
  • Neutral (4%, 6 Votes)

Total Voters: 137

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7 thoughts on “COVID-19 vaccine end game and why children matter

  1. Helen Robertson says:

    I think that in the long term, control of COVID 19 disease to manageable levels in the community will need immunisation of children (perhaps from early teens) as well as all age groups older than that. However it doesn’t have to be done using this year’s vaccines. In a couple of years there will be more effective and better evaluated vaccines suitable for teenagers. In the meantime we can get the adult population done. The AstraZeneca vaccine in its current form will be superseded but I still happily had it myself now. I’ll get a reasonable degree of protection now from it. Perhaps next year I’ll get a booster of some other type to cover new variants. It’s a work in progress. We can’t let “the best” be the enemy of “the good”.

  2. john barr says:

    Totally disagree with vaccinating kids. The morbidity in children is tiny, this is a completely untried technology and it is not even a vaccine.
    It is a treatment which suggests that it may make the disease milder, reduce hospitalization and death. Since children are at minimal risk anyway, it is wrong to treat them, especially as the long-term risks are completely unknown.

    This is completely laying aside the question of whether it is right to treat the population of the world against an infection which has an IFR of 0.05%, unless you are over 75 and more so if you have significant comorbidities. I am 70, fit and only agreed to have it as I believe the extremely authoritarian government here won’t allow travel without proof of vaccination. The human rights issues involved in this are quite another matter. I believe our human rights have already been taken away, especially by some of the deranged individuals currently in charge of our states.
    No doubt I will be regarded as just another hysterical voice, but I would like to know why the medical profession has been so aquiescent in not even challenging the information put out by the authorities, which go against known facts. For example, there is very little evidence that masks are of benefit, and they cause significant harms.

  3. Anonymous says:

    What the international results tell us clinically to date-
    None or very few healthy children have died or ended up in intensive care even in the epicentres of the pandemic.
    Elderly – or 60+ mainly males died.
    Therefore the more mature require the vaccinations – the very young do not.
    Vaccinated people do not become sick and are protected from major effects of the illnesses but they still become infected and can act as asymptomatic vehicles of the the infection.
    The young have an avalanche of important vaccinations against diseases which are more specific to them, diphtheria,polio, etc. What is the pressing need for vaccination against a disease which is relatively benign in the young other than a mathematical construct? We should await further studies rather than pressing on with vaccinations via vaccines which to date have only provisional approval and batch release assessments are undertaken . Currently NO covid vaccine is fully approved by FDA.
    So mass hysteria is not confined to the general public but rears it’s head in the medical profession.
    So should children be vaccinated with vaccines with conditional emergency approval when they are not in danger?

  4. Anonymous says:

    The idea of including children in a vaccination rollout that is not yet proven for adults and includes a gene therapy (CDC definittion) method of vaccination is a very high risk strategy, particularly for a disease that has not resulted in any childhood mortality in Australia (

    So far the TGA report 200+ deaths after vaccination (causality unknown) and senate testimony has been provided that 11,000+ adverse events have been recorded such that the TGA have stated that they are unable to keep up with the reports and establish causality (or absence of).

    This article correctly refers to the low efficacy for symptomatic disease in the two main studies – AZ and Pfizer. In fact the Pfizer study showed only 12% efficacy for symptomatic disease overall (1594 vs 1816 cases[1]), and no impact on death rates. The Pfizer (the largest) study of all the gene-based vaccine candidates did not include a large number of children (N=103, none under 16, and no instance of disease in either group[1]) and a basic power calculation would in fact show that, given the near-zero fatality rate of covid19 at even the highest prevalence rate in Australia (April 2020), would need 3m or so patients in any study to show efficacy. Such a study has not been performed or likely to be.

    Assuming efficacy of a novel drug and applying this to a group at negligible risk of severe disease is something that we should have given up long ago, with the advent of medical ethics from the late 40s through to now. We should not be taking a step back. If a rollout in children were to result in any lives lost following vaccination (as appears to be the case in the US and Europe), the damage done to the overall perception of vaccine medicine and the public’s trust in the medical establishment may take decades to recover.

    Ref: [1] Pfizer CDC Briefing document p42 link:

  5. Max says:

    At present the fatality risk for children from COVID is nearly the same as that risk from COVID vaccination. Hard to argue as a doctor that it is in the best interests of the individual child to have the vaccine.
    We do not recruit minors to fights in wars of any kind, even wars against a virus. Our job as adults is to protect and nurture children, not to use them as cannon fodder in a battle to achieve herd immunity for a community.
    In addition, their education is not some optional extra to be traded against preserving the lives of older adults; or against preserving ‘the economy’ (in which they’ll be unable to participate due to lack of that education).
    Of all the faults of lockdown, the notion that we can turn off the education of half a generation of children is the most perverse. Schools should remain open, and the rest of society deals with any consequences.
    That is no less important a duty of care.

  6. Philip Murray says:

    A key issue is that the Government is averse to setting a target at which it might fail. So there needs to be strong encouragement from relevant experts for the government to act on principle rather than worry about the perception if it fails.
    The “herd immunity may be feasible” should be followed up earlier in the article with clear statement that it should undoubtedly be Australia’s goal. “Our best bet” as a conclusion suggests there is some other way? If so what is it? “There is no alternative” is surely the message and it need to be more clearly evangelised and help force the Government into clarity.
    The child vaccination debate is then contingent on that argument.
    In summary, the detail is great and instructive, but the article structure and conclusion was a bit worrisome. improved!

  7. Robert Hall says:

    In my view the key issue here is the endpoint of efficacy. We need efficacy against transmission to even consider herd immunity effects. Most studies of vaccine efficacy do not have transmission as an endpoint, rather they have laboratory confirmed clinical disease. As far as I am aware efficacy against transmission may be somewhere in the 30% to 50% range in population studies where it seems several different vaccines have been used. Examples are the rate of transmission of covid-19 to households of vaccinated and unvaccinated health care workers. If this level of efficacy is so, then the current generation of vaccines cannot produce sufficient herd immunity to provide high level control of covid-19, particularly against variants with high levels of transmission. This means our objective has to be the prevention of morbidity and premature death, since we cannot stop transmission with vaccine alone. This will require 100% cover of vaccination.

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