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COVID-19 interventions in children: a balancing act
  1. Marieke Emonts1,2
  1. 1Newcastle University, Newcastle upon Tyne, UK
  2. 2Newcastle upon Tyne Foundation Trust Hospitals, Great North Children’s Hospital, Newcastle upon Tyne, UK
  1. Correspondence to Professor Marieke Emonts, Paediatric Immunology, Infectious Diseases & Allergy, Great North Children's Hospital, Newcastle upon Tyne NE1 4LP, UK; marieke.emonts{at}

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The Food and Drug Administration (FDA) and Medicines and Healthcare products Regulatory Agency (MHRA) have approved COVID-19 vaccines (under emergency use authorisation) for young people aged 12 and above, but the world seems divided regarding national approval for use in children aged 12–15 years old.

The USA, Canada, New Zealand, Australia and several European countries are offering vaccination to all young people in this age group, while in the UK the first dose of the vaccine is available for all children aged 12–17 years old, but subsequent doses only for those with increased risk of severe COVID-19 aged 12–15 years. This variation between countries in vaccination policy was also observed, for example, with meningococcal vaccination, and epidemiological and cultural differences between countries likely play a role.

The long-term effect of COVID-19 infection in children is still unknown, which makes balancing the benefits and risks of vaccination accurately very difficult. Many studies on COVID-19 are being published weekly, and often information is made available in preprints prior to peer review. While prompt sharing of information widely to educate scientists and physicians quickly in an evolving pandemic is desirable to allow prompt implementation of therapy, it also means the rigorous peer review that allows detection of methodological flaws of studies only takes place later. Several initially influential papers have been retracted. Interpreting the enormous amount of manuscripts and judging their quality are challenging, and understandably even more so for the wider public. While information is shared quickly on social media, disproving false information takes much more effort. Additionally, the insatiable hunger for information reduces capacity for much-needed reflection.

Pressure is put on paediatricians to push for vaccination for all. Both population and individual risk to benefit ratios are important considerations for vaccination policies. Interpreting available data on potential risks and benefits is not straightforward, and additionally other factors influence this complex decision making. All these need to be taken into account. In general the higher and more severe the disease burden, the higher the risks one might be willing to take to aim to prevent/reduce disease.

This means as a minimum one needs to look at:

  • Disease severity and implications in the short and long term.

  • Disease incidence.

  • Aim of vaccination: prevention of infection or severe disease.

  • Vaccine efficacy.

  • Vaccine side effects.

COVID-19 infections in healthy children and young people in general are mild, or even asymptomatic, with low mortality.1 Certain risk factors for more severe disease, such as chronic pulmonary disease and neurological disorders, are recognised, and for these children vaccination is available.2 Less clear is the reported increased risk for certain ethnic minorities. Is this a true increased risk of severe disease once infected, or does this reflect social deprivation and the need for parents to continue working to ensure income for the family, associated with increased exposure? When more children are infected, one will also see some with more severe infection. Next to acute respiratory illness, the direct risks of SARS-CoV-2 to be considered are multisystem inflammatory syndrome in children (MISC), although rare, and the potential for long COVID-19. Estimating the contribution to disease burden long term at this stage of the pandemic is challenging due to lack of information. From surveillance including uninfected controls, symptoms that contributed to long COVID-19 in children are less common in those aged 12–18 years old compared with adults, and also occur in non-SARS-CoV-2-infected young people.3

The indirect risks are disruption of education, isolation and reduced interaction with friends and family. Relative risk of disease and complications, both short and long term, are important determinants. To establish the risk of becoming unwell upon infection, the total number infected would need to be known. However, only those fulfilling symptomatic criteria are eligible for PCR testing, while those with mild or asymptomatic infection will not be counted apart from when included in surveillance programmes. Serology is not routinely available everywhere to confirm previous exposure in those who display MISC or long COVID-19 symptoms. Testing availability differs across the globe, and details are not always clear. This will be further influenced by costs of tests, who pays for testing and the consequences of test results. Is there an incentive to stop mandated self-isolation early with negative test results? In short, denominators are variable, which means interpreting and comparing data from different settings to establish risks of severe infection become a challenge.

The benefits of vaccination for most young people who would, if infected, only develop mild symptoms at most are that of contribution to herd immunity, reduced risk of educational disruption and reducing spread of infection. While contracting the disease and spreading it after infection is still possible, disease severity is decreased, with lower viral loads and reduced duration of viral shedding. Initial reports showed a vaccine effectiveness of around 95%.

The USA currently reports higher incidence of young people admitted with COVID-19 attributed to the rise in the Delta variant. This will contribute to the decision to vaccinate. This steep rise in hospital admission was not observed in Europe. While a concern in itself, it is unclear if this is a true increased severity of disease. European data on unselected febrile children presenting to tertiary emergency departments pre-COVID-19 show admission criteria are variable and site-dependent also when corrected for severity of illness.4 We initially had a lower threshold for admission of children with COVID-19, as the course of the disease in children was not clear at the beginning of the pandemic. Currently only those who need hospital-based care are admitted, and this is only a small proportion of children infected. What the threshold is for hospital or paediatric intensive care unit admission in US hospitals is not defined. In addition, coinfections with, for example, Respiratory Syncytial Virus (RSV) likely play a role in disease severity and admission rates.

In any case for preventive measures such as vaccination, the benefits must outweigh the potential risks. The most discussed risk of COVID-19 vaccines is myocarditis after the second dose, also described in younger adults who had the BNT162b2 mRNA COVID-19 vaccine (Pfizer-BioNtech) or the mRNA-1273 COVID-19 vaccine (Moderna).5 While this is mostly described as mild and resolves/improves, there might be longer-term risk of development of fibrosis and subsequent arrhythmias.6 As vaccination in the younger age group was only recently introduced, knowledge about the exact risks is still evolving, and control data in a matched unvaccinated population are not yet available. This information would provide an opportunity for improved risk assessment of vaccination.

Currently only the BNT162b2 mRNA vaccine has been approved for children aged 12–17 years old, but it is expected that more conventional COVID-19 vaccines will follow. Depending on the side effect profile, this might tip the balance in favour of full vaccination. The vaccination uptake in adults in the USA is lower and patchy, compared with the UK, which might have tipped the balance to vaccinating their younger people as well to obtain wider population protection.

Unfortunately with the rise of the Delta variant, the ability particularly to prevent infection is less encouraging and wanes over time, with reducing vaccine effectiveness for both the Alpha and Delta SARS-CoV-2 variants.7 8 The beneficial effect in preventing severe disease remains, but reducing infection prevention effectiveness would mean vaccinating might give less/shorter benefit than initially thought. Providing longer-term population protection would likely require booster vaccinations as currently used for influenza and is now being implemented for SARS-CoV-2. As complications from COVID-19 vaccinations were mostly observed not with the first but second doses, this prompts the question what the potential risk would be of subsequent required booster doses to maintain protection from infection. This is not clear at this moment given the limited data available.

On top of this all, while the COVID-19 pandemic is evolving, so is the availability of new evidence, and practice should change accordingly. Decisions that appear justified today might be different with the knowledge of next week or month. We as paediatricians, but also families, are sometimes uncomfortable with this uncertainty and any advice to families should therefore be put in context and limitations explained.



  • Twitter @mariekeemonts

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Commissioned; internally peer reviewed.

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