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Covid-19: JCVI opts not to recommend universal vaccination of 12-15 year olds

BMJ 2021; 374 doi: (Published 03 September 2021) Cite this as: BMJ 2021;374:n2180

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Rapid Response:

Public health logic of COVID-19 vaccinations

Dear Editor

The decision of the United Joint Committee on Vaccination and Immunisation (JCVI) not to recommend immunisation for younger age groups should not surprise anyone. Amidst the apparent controversy, it is helpful to pause and examine the case for COVID-19 vaccination carefully, from first principles.

Vaccination policy normally works on two levels:

1. Individual protection. You get vaccinated to reduce your chances of getting sick, disabled, or dying from Disease X. This is a simple risk-benefit equation; If I take the vaccine, will the reduction in harm to me from the disease probably be greater than the harm that the vaccine may cause me?

If the answer is ‘yes’, most would opt for vaccination.

2. Societal protection. This is more complex and introduces ethical dilemmas. You vaccinate someone (or are vaccinated yourself) to reduce transmission and protect others from potential infection, sickness or death; Should someone else (even a child) be put at risk of harm (side-effects) to protect another? Or to protect people of the future through disease eradication?

The answer depends on societal values, but also requires a particularly safe vaccine.

Nearly all existing vaccines are target children – they either address major childhood diseases, or diseases of all ages for which early vaccination provides life-long immunity. While personal protection is the main driver, herd immunity is cited for some, such as measles vaccination.

COVID-19 is another nasty infectious disease, and vaccination decisions require these same considerations. However, the benefit-risk calculations for children differ in important ways.

1. Does the vaccine benefit the vaccinated?

Initial trials showed vaccinated people suffered less severe COVID-19 symptoms than unvaccinated.[1] Despite waning effectiveness over time, vaccines provide some protection against symptomatic disease.[2] But severity and mortality is highly associated with older age and specific co-morbidities.[3] Children are extremely unlikely to die – well children at less than 1 per million,[4,5] the risk to the elderly is over 1000 times higher.[6] So vaccinating a million well children will probably prevent, at most, one death. It may reduce post-viral syndromes (long COVID) but these are also uncommon – less than 2% after 2 months.[7]
COVID-19 vaccine side-effects are well recognized,[8] but incidence is poorly monitored and understood. The US voluntary reporting system (VAERS) has higher rates of vaccination-associated death than all other vaccines combined over the past 20 years.[9] The initial targeting of frail elderly people will have influenced this, but similar mortality is not reported for flu vaccines, and side effects such as myocarditis are targeting the young.[10] Blood clotting disorders (e.g. heart attacks, cerebral venous sinus thromboses) are associated with vaccination, as with COVID-19 itself.[11-13] As the mRNA vaccines are a new technology, longer-term side-effects remain speculative.

To receive full benefit, a vaccine recipient must be non-immune. While cross-immunity from other coronaviruses is unpredictable,[14] a significant proportion of the population who previously had COVID-19 have as good or better immunity than the vaccine provides.[15,16] Vaccination may add temporarily to this protection, but they are so well protected that clinical benefit will be minimal.[17]

So in balance, in the elderly where COVID-19 mortality is up to 7% of infections,18 and others with major risk factors, vaccination against COVID-19 seems appropriate. The benefits likely outweigh risks. In children and young adults, the equation appears weighted towards risk.[5,19] For anyone who has already had COVID-19, no clinical benefit is demonstrated.

2. Does the vaccine protect others?

For the vaccination to be altruistic – protect others – it must greatly reduce transmission. Leaving the ethics aside, we can question this impact:

A. If the vaccine blocks transmission, does that help anyone?

Only if the vulnerable others are not vaccinated, or their vaccination is poorly protective. Evidence suggests it is protective for at least for a few months once immunity is established.[20] So only those voluntarily unvaccinated, or ineligible for/unresponsive to vaccination, will significantly benefit, including children and those with rare contra-indications.[21]

B. Does it block transmission?

Despite early hopes, it does not. Vaccinated people who become infected have similar viral loads (similar infectiousness) as unvaccinated people.[20,22] But having less symptoms,[20] they may be less likely to self-isolate, potentially increasing risk to the vulnerable.

C. What if almost everyone is vaccinated?

Despite high hopes of gaining transmission-blocking ‘herd immunity’ through mass vaccination, this seems unachievable. In some circumstances, vaccination could promote infection.[23] Vaccinated people transmit the virus. Israel, Iceland, and the UK, with the vast majority of adults vaccinated, record relatively high continuing transmission.[24] Allowing non-vulnerable people to gain broader, longer-lasting post-infection immunity may protect the vulnerable more effectively and safely. This logic underpins the UK's policy of not introducing varicella (chickenpox) immunization, preventing waning vaccine induced immunity from leading to more severe adult infection.

D. What about variants?

As vaccinated people become infected with similar viral loads, narrow vaccine-induced immunity against spike protein may favour variant selection. Post-infection immunity is more broadly active against current variants.[25] The argument that unvaccinated drive development of variants has a poor evidence-base.

To summarize what we do know:

From a public health standpoint, it makes poor sense to impose vaccine side- effects on people at minimal risk of severe COVID-19. The argument that it protects others is weak or contrary to evidence. This conclusion suggests a policy of targeting vaccination to those at highest risk, allowing broader post-infection immunity to provide community protection.

UK politicians might do well to reflect on the country's comparative success, since the Whooping Cough vaccination scare of the 1970s, in maintaining high levels of immunisation against significant childhood diseases. Much credit lies in maintaining a clear evidence-based policy in which the JCVI has played a key role, thoroughly laid out in "The Green Book" (Immunisation against infectious disease).[26] It would be regrettable if events linked to the COVID-19 immunisation programme ended up undermining the UK's whole vaccine effort.


Competing interests: Dr Salmon is a Crematorium Medical Referee for the Cardiff Council Crematorium, Thornhill, Cardiff and is remunerated on a fee for service basis. Dr Bell is employed in the development and clinical evaluation of diagnostic tests for SARS-COV-2 infection. Both authors are members of HART.

06 September 2021
David Bell
Public health physician
Dr Roland Salmon, retired Consultant (Medical) Epidemiologist and former Director of the Communicable Disease Surveillance Centre
Independent consultant
Issaquah, WA, USA