A guide to vaccinology: from basic principles to new developments

Vaccines Save At Least 154 Million Lives In 50 Years: WHO

Vaccinations for 14 diseases have saved at least 154 milliion lives in 50 years, the UN said (AHMAD AL-RUBAYE)

Global immunisation efforts have saved at least 154 million lives in the past 50 years, the World Health Organization said Wednesday, adding that most of those to benefit were infants.

That is the equivalent of six lives saved every minute of every year of the half century, the UN health agency said.

In a study published in the Lancet, WHO gave a comprehensive analysis of the impact of 14 vaccines used under the Expanded Programme on Immunisation (EPI), which celebrates its 50th anniversary next month.

"Vaccines are among the most powerful inventions in history, making once-feared diseases preventable," WHO chief Tedros Adhanom Ghebreyesus said in a statement.

"Thanks to vaccines, smallpox has been eradicated, polio is on the brink, and with the more recent development of vaccines against diseases like malaria and cervical cancer, we are pushing back the frontiers of disease," he said.

"With continued research, investment and collaboration, we can save millions more lives today and in the next 50 years."

The study said infants accounted for 101 million of the lives saved through immunisation over the five decades.

"Immunisation was the single greatest contribution of any health intervention to ensuring babies not only see their first birthdays but continue leading healthy lives into adulthood", WHO said.

Over 50 years, vaccines against 14 diseases -- diphtheria, Haemophilus influenza type B, hepatitis B, Japanese encephalitis, measles, meningitis A, pertussis, invasive pneumococcal disease, polio, rotavirus, rubella, tetanus, tuberculosis, and yellow fever -- had directly contributed to reducing infant deaths by 40 percent, the study found.

For Africa, the reduction was more than 50 percent, it said.

The vaccine against measles -- a highly contagious disease by a virus that attacks mainly children -- had the most significant impact.

That jab accounted for 60 percent of the lives saved due to immunisation, according to the study.

The polio vaccine means that more than 20 million people are able to walk today who would otherwise have been paralysed.

The study also showed that when a vaccine saves a child's life, that person goes on to live an average of 66 years of full health on average -– with a total of 10.2 billion full health years gained over the five decades.

"These gains in childhood survival highlight the importance of protecting immunisation progress," WHO said, pointing to accelerating efforts to reach 67 million children who missed at least one vaccination during the Covid pandemic.

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Global Immunization Efforts Saved 154 Million Lives Over Past 50 Years: The Lancet

A major landmark study to be published by The Lancet reveals that global immunization efforts have saved an estimated 154 million lives – or the equivalent of 6 lives every minute of every year – over the past 50 years. The vast majority of lives saved – 101 million – were those of infants.

The study, led by the World Health Organization (WHO), shows that immunization is the single greatest contribution of any health intervention to ensuring babies not only see their first birthdays but continue leading healthy lives into adulthood.

Of the vaccines included in the study, the measles vaccination had the most significant impact on reducing infant mortality, accounting for 60 per cent of the lives saved due to immunization. This vaccine will likely remain the top contributor to preventing deaths in the future.

Over the past 50 years, vaccination against 14 diseases (diphtheria, Haemophilus influenzae type B, hepatitis B, Japanese encephalitis, measles, meningitis A, pertussis, invasive pneumococcal disease, polio, rotavirus, rubella, tetanus, tuberculosis, and yellow fever) has contributed to reducing infant deaths by 40 per cent globally, and by more than 50 per cent in the African Region.

"Vaccines are among the most powerful inventions in history, making once-feared diseases preventable," said WHO Director-General, Dr Tedros Adhanom Ghebreyesus. "Thanks to vaccines, smallpox has been eradicated, polio is on the brink, and with the more recent development of vaccines against diseases like malaria and cervical cancer, we are pushing back the frontiers of disease. With continued research, investment and collaboration, we can save millions more lives today and in the next 50 years."

The study found that for each life saved through immunization, an average of 66 years of full health were gained – with a total of 10.2 billion full health years gained over the five decades. As a result of vaccination against polio, more than 20 million people are able to walk today, who would otherwise have been paralysed, and the world is on the verge of eradicating polio, once and for all.

These gains in childhood survival highlight the importance of protecting immunization progress in every country of the world and accelerating efforts to reach the 67 million children who missed out on one or more vaccines during the pandemic years.

Monumental efforts to increase access to vaccination over five decades

Released ahead of the 50th anniversary of the Expanded Programme on Immunization (EPI) to take place in May 2024, the study is the most comprehensive analysis of the programme's global and regional health impact over the past five decades.

Founded in 1974 by the World Health Assembly, EPI's original goal was to vaccinate all children against diphtheria, measles, pertussis, polio, tetanus, tuberculosis, as well as smallpox, the only human disease ever eradicated. Today, the programme, now referred to as the Essential Programme on Immunization, includes universal recommendations to vaccinate against 13 diseases and context-specific recommendations for another 17 diseases, extending the reach of immunization beyond children to adolescents and adults.

The study highlights that fewer than 5 per cent of infants globally had access to routine immunization when EPI was launched. Today, 84 per cent of infants are protected with 3 doses of the vaccine against diphtheria, tetanus and pertussis (DTP) – the global marker for immunization coverage.

Nearly 94 million of the estimated 154 million lives saved since 1974, were a result of protection by measles vaccines. Yet, there were still 33 million children who missed a measles vaccine dose in 2022: nearly 22 million missed their first dose and an additional 11 million missed their second dose.

Coverage of 95 per cent or greater with 2 doses of measles-containing vaccine is needed to protect communities from outbreaks. Currently, the global coverage rate of the first dose of measles vaccine is 83 per cent and the second dose is 74 per cent, contributing to a very high number of outbreaks across the world.

To increase immunization coverage, UNICEF, as one of the largest buyers of vaccines in the world, procures more than 2 billion doses every year on behalf of countries and partners for reaching almost half of the world's children. It also works to distribute vaccines to the last mile, ensuring that even remote and underserved communities have access to immunization services.

"Thanks to vaccinations, more children now survive and thrive past their fifth birthday than at any other point in history," said UNICEF Executive Director Catherine Russell. "This massive achievement is a credit to the collective efforts of governments, partners, scientists, healthcare workers, civil society, volunteers and parents themselves, all pulling in the same direction of keeping children safe from deadly diseases. We must build on the momentum and ensure that every child, everywhere, has access to life-saving immunizations."

In 2000, Gavi, the Vaccine Alliance, which includes WHO, UNICEF and the Bill & Melinda Gates Foundation (BMGF) as core founding members, was created to expand the impact of EPI and help the poorest countries in the world increase coverage, benefit from new, life-saving vaccines and expand the breadth of protection against an increasing number of vaccine-preventable diseases. This intensified effort in the most vulnerable parts of the world has helped to save more lives and further promote vaccine equity. Today, Gavi has helped protect a whole generation of children and now provides vaccines against 20 infectious diseases, including the HPV vaccine and vaccines for outbreaks of measles, cholera, yellow fever, Ebola and meningitis.

"Gavi was established to build on the partnership and progress made possible by EPI, intensifying focus on protecting the most vulnerable around the world," said Dr Sania Nishtar, CEO of Gavi, the Vaccine Alliance. "In a little over two decades we have seen incredible progress – protecting more than a billion children, helping halve childhood mortality in these countries, and providing billions in economic benefits. Vaccines are truly the best investment we can make in ensuring everyone, no matter where they are born, has an equal right to a healthy future: we must ensure these efforts are fully funded to protect the progress made and help countries address current challenges of their immunization programmes."

Immunization programmes have become the bedrock of primary health services in communities and countries due to their far reach and wide coverage. They provide not only an opportunity for vaccination but also enable other life-saving care to be provided, including nutritional support, maternal tetanus prevention, illness screenings and bed net distribution to protect families from diseases like malaria.

Since the study only covers the health impact of vaccination against 14 diseases, the number of lives saved due to vaccination is a conservative estimate and not a full account of the life-saving impact of vaccines. Societal, economic or educational impacts to health and well-being over the 50 years have also contributed to further reductions in mortality. Today, there are vaccines to protect against more than 30 life-threatening diseases. 

While the HPV vaccine, which protects against cervical cancer in adults, was not included in the study, it is expected to prevent a high number of future deaths as countries work towards increasing immunization targets aimed at eliminating cervical cancer by 2030. New vaccine introductions, such as those for malaria, COVID-19, respiratory syncytial virus (RSV) and meningitis, as well as cholera and Ebola vaccines used during outbreaks, will further save lives in the next 50 years.

Saving millions more is "Humanly Possible"

Global immunization programmes have shown what is humanly possible when many stakeholders, including heads of state, regional and global health agencies, scientists, charities, aid agencies, businesses, and communities, work together.

Today, WHO, UNICEF, Gavi, and BMGF are unveiling "Humanly Possible", a joint campaign, marking the annual World Immunization Week, 24-30 April 2024. The worldwide communication campaign calls on world leaders to advocate, support and fund vaccines and the immunization programmes that deliver these lifesaving products – reaffirming their commitment to public health, while celebrating one of humanity's greatest achievements. The next 50 years of EPI will require not only reaching the children missing out on vaccines, but protecting grandparents from influenza, mothers from tetanus, adolescents from HPV and everyone from TB, and many other infectious diseases.

"It's inspiring to see what vaccines have made possible over the last fifty years, thanks to the tireless efforts of governments, global partners and health workers to make them more accessible to more people," said Dr Chris Elias, president of Global Development at the Bill & Melinda Gates Foundation. "We cannot let this incredible progress falter. By continuing to invest in immunization, we can ensure that every child – and every person – has the chance to live a healthy and productive life."

How Many Lives Did COVID Vaccines Save? Scientists Have An Estimate

As put by Professor Adrian Esterman, chair of biostatistics and epidemiology at the University of South Australia: "One mistake that vaccine sceptics keep bringing up is that the majority of COVID-related deaths are in those who have been vaccinated – therefore the vaccines do not work, or even cause death.

"The authors rightly point out that a fairer comparison is to look at the death rate in those unvaccinated compared to those vaccinated, which immediately shows how important the vaccination program has been in preventing COVID-19-associated deaths."

Was the vaccine delay a life-saving fluke?

The government of the day was rightly roasted for the glacial pace of Australia's vaccine rollout.

In mid-2021, Australia ranked second last for vaccine coverage among OECD nations. Only 10 per cent of NSW's over-50s were fully vaccinated, and a largely unprotected population was left "dangerously vulnerable", the researchers wrote.

But by January 2022, 95 per cent of that population was fully covered in time for the peak of the Omicron wave.

And the fact that so many had been freshly vaccinated might have delivered an advantage because the public's immunity hadn't yet waned, the researchers said.

"The delay of the vaccination program was actually advantageous since it limited the extent of immunity waning, and so increased protection during the Omicron period.

"Fortuitously, Australia's slow start should, in hindsight, not necessarily be viewed as detrimental."

Perhaps, then, a happy fluke for the Lucky Country.

Anti-vaxxers seize on data that shows more vaccinated people have died from COVID-19 – but the death rate for those unvaccinated is far higher.Credit: Emma Young

"Australia was further lucky that when we opened up, Omicron was the circulating virus that was less lethal than, say, Delta," says Professor Tony Blakely, an epidemiologist at the University of Melbourne.

"But this paper makes the important point that even Omicron, in an unvaccinated population, would have had a massive death toll."

Blakely, who was not involved in the study, stresses that it probably underestimated the number of lives saved because high vaccination rates would have reduced transmission, as well as protecting people from severe disease.

A reporting snafu means a caveat to death rate data

An incident from last week warns against the seductive compulsion of drawing conclusions from raw data.

On Friday, media outlets scrambled to update what first appeared as the week's good-news story – for the first time in years, Australia had gone a week without anyone dying of COVID-19.

But it soon emerged that wasn't the case. People most certainly had died with COVID-19 that week. Headlines hailing the zero-death week were altered, dampened and deleted.

COVID-19 deaths are at a low point - but not zero.Credit: Health Department

The claims were triggered by data from the National Notifiable Diseases Surveillance System showing the rolling seven-day COVID-19 death average fell to zero on a few days between February 29 and March 5.

But there's now a months-long delay in getting COVID-19 death data into the federal system, experts say.

Later on Friday, more data fed in and the death rate's pulse returned. Since Friday's reporting snafu, a caveat has appeared below the graph charting deaths on the government's COVID-19 reporting site, explaining that changes to how states report fatalities have reduced our ability to track mortality from the virus.

The rolling average death rate on the government's chart, in future, should be treated as a significant underestimate.

In any case, deaths and hospitalisations are low. But Esterman says we shouldn't get complacent.

"Last month, there were over 250 active COVID-19 outbreaks in residential aged care homes, and only 36 per cent of Australians aged 75 and over have had a booster shot within the last six months. We see very little messaging from any of our governments encouraging elderly people to get vaccinated," Esterman says.

"This is not good enough. We should at the very least still be doing all we can to protect our vulnerable population."

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