Herd immunity for all manner of diseases is still a huge challenge, but we can get there

A Covid-19 inoculation programme is under way in Bangkok in September 2021. EPA

One of my earliest memories is being carried screaming for my smallpox vaccination in India. The irregular scar remains a daily reminder of the condition that killed 500 million people in the century before its elimination in 1980. Smallpox remains the only human disease ever to be eradicated.

That was due not just to the vaccine, but the unprecedented co-operation between the US and Soviet Union during the depths of the Cold War. It was a golden era of faith in multilaterals, allowing the World Health Organisation to assert exemplary leadership. The relatively simple variola virus stood no chance against the combination of modern technology and global solidarity.

Of course, this romantic distillation of history must be qualified by that era’s geopolitics. The superpowers were simultaneously researching the weaponisation of smallpox, and global vaccination neutralised the mutual threat. Investing $300 million over a decade ended the scourge, with costs recouped within a month.

Could our success against smallpox be repeated? Oral polio vaccines cost a meagre $0.10 to $0.20 a dose, and the standard three-dose regime provides 99 per cent protection. I was hopeful during a brief moment in 2001 watching Afghan militants clutching polio vaccine flasks instead of AK47s. They were honouring a ceasefire during their country’s civil war to vaccinate 5.7 million children. But repeated cycles of violence and instability allowed the wild polio virus to remain endemic there and in Pakistan, where courageous vaccinators still get killed by hostile, misinformed communities.

That has global impact. Almost eliminated by the 1980s, these days outbreaks of variant polioviruses are reported in 33 countries, with the number of paralysed kids increasing by 60 per cent.

The polio story illustrates no one is safe from vaccine-controllable conditions until all are safe. Or more precisely and depending on specific diseases, 70 to 90 per cent of at-risk groups must be rendered immune.

Unfortunately, however, collective solidarity has been fraying. The WHO has said vaccine hesitancy is a top global health threat, with public attitudes shaped by complacency, convenience and confidence factors. New Yorkers, for example, have gotten complacent with polio, with only 40 per cent of children immunised in some neighbourhoods.

Shadi's take on herd immunity

In our hyper-information age, people are not informed accurately or good at evaluating personal risks

Convenience entails the availability, affordability and delivery of vaccines. The world made steady progress under a remarkable global Vaccine Alliance (Gavi) that has vaccinated nearly a billion children this century, preventing 16 million deaths. But Covid-19 disruptions from 2019 to 2021 meant that 48 million new-borns did not receive even a single dose of their basic vaccines. Increased conflicts and climate-induced catastrophes alongside resource-strapped health systems are further woes: a fifth of children worldwide are now unvaccinated or under-vaccinated.

Confidence concerns trust in vaccination safety and effectiveness. As with any biological product, vaccines may cause side-effects. Nearly all are minor but there is an extremely small risk (1-2 per million) of serious adverse reactions including unforeseen allergies, nearly all of which are manageable.

The measles-mumps-rubella (MMR) vaccine provides a salutary example. A 1998 paper in the venerable journal Lancet claimed an autism link to MMR, but was redacted as false 12 years later. In the meantime, hundreds of thousands of children withdrew from measles vaccination with significant negative consequences.

In our hyper-information age, people are not informed accurately or good at evaluating personal risks. These are easily misrepresented, exaggerated, and distorted on social media when ignorance, ideology or just mischief-making infiltrate the mix.

In the face of vaccine hesitancy, states have tried coercion, such as compulsory immunisations of kids before school admission. But centuries of experience suggests that coercive approaches are not the most effective in securing public health.

Such concerns crowded my mind recently while touring the Serum Institute of India, the world’s biggest vaccines manufacturer. I was examining how its new HPV vaccine against cervical cancer is rolled out in India and how to get an early pipeline into Africa.

Vaccine-preventable cervical cancer is a leading cause of female mortality. The WHO target of cervical cancer elimination by 2030 requires vaccinating 90% of young girls and, ideally, also boys to reduce overall virus transmission. An example of male solidarity with females, universal HPV vaccination is an eminently practical way to walk the gender equality talk.

But it is not easy. While India has all the necessary technology, finance, political will and organisational capacity, overcoming socio-cultural constraints necessitates immense mobilisation.

However, it is doable thanks to Serum Institute lowering HPV vaccine costs to $2, compared with market-monopolising manufacturers retailing it at $250 in the West. Without such economies for all vaccines, the ambition of universal health coverage, a lynchpin of the UN Sustainable Development Goals, will remain elusive.

Vials of freshly manufactured Novavax Covid-19 vaccines wait to be labelled at the Serum Institute of India in in Pune, India in 2022. AP Photo

Reducing dependence on monopoly vaccine producers requires diversifying supply. But vaccine development is risky. Most candidate vaccines fail and exhaustive safety and multi-phased efficacy trials may take 10-30 years and cost $3.5 billion to $5bn.

Understandably, established vaccine makers are reluctant to share intellectual property before recouping their own costs, giving good returns to investors and saving enough to bankroll their next innovation. Meanwhile, poor communities with huge disease burdens are under-served. This causes major tension between developed and developing nations at the World Trade Organisation, with wider ramifications such as current negotiations over a new, post-Covid “Pandemic Treaty”.

But all is not gloom. New technologies such as the mRNA platform delivered a coronavirus vaccine in record time. Combining that with fast-progressing artificial intelligence promises cost-effective vaccine solutions for other pathogens.

It is more than 60 years since I screamed through my smallpox jab. Last month, I joined a new cohort of screaming toddlers at my local vaccination centre. They were getting their basic immunisations and I was there for boosters for some of the same conditions: tetanus, diphtheria and pertussis. Advancing age and associated chronic diseases meant that my immune system needed boosting.

We all got sugar-free lollipops for good behaviour from the kind nurse. As I sucked my lollipop, I realised that mine is the first full generation that survived thanks to the vaccine revolution. Demographic shifts in our 8-billion world mean that 800 million over-65s compete now with their 650 million grand-children aged under five years for the 25 or so available vaccines, with science promising yet more.

Lollipop makers are doubtless relishing the prospects for scaling-up. More seriously, the vaccine system must do the same. That requires greater solidarity on an unprecedented scale not just across borders but across generations.