“Only clean water and antibiotics have had an impact on childhood death and disease that is equal to that of vaccines” – World Health Organization (WHO)
In the 20th century, when most of you reading this were born, nearly 1.7 billion people died from infectious diseases.
Most of the diseases in the sobering infographic linked above are now vaccine preventable through the creative collective brilliance of many scientists. Smallpox, influenza, diarrhoea (rotavirus), whooping cough, meningitis, tetanus, Hepatitis B, rabies, and measles are the diseases responsible for carrying off most of those 1.7 billion people.
While the First World War raged for over four years and took the lives of 16,697 New Zealanders, in 1918 influenza took about half as many in the space of just two months (8600 New Zealanders died).
So how many lives have vaccines saved? I have never been able to find an overall total, but one bunch of scientists (ScienceHeros.com) estimate that Edward Jenner alone was responsible for saving 530 million lives. In other words, that is how many deaths from smallpox are estimated to have been prevented. I thought that sounded like a lot before I remembered that the estimate for the 20th century alone is about 300-500 million so maybe this is actually a conservative estimate although I have not been able to find any convincing estimates on this.
Imagine inventing something that saved half a billion lives!
That made me think of another major killer – measles.
Already this century the WHO has estimated that measles vaccine alone has saved over 17 million lives. A couple of doses at a cost of about $NZ1 works a treat. And if you think measles never really hurt any Kiwis then I suggest you have a look at this New Zealand timeline and contemplate how small the population was during these years. In 1900 we numbered little more than 700,000
The man responsible for this impressive achievement is Maurice Hilleman who developed a measles vaccine which is estimated to have saved 118 million lives since the 1960s. Every country in the world uses measles vaccine and the disease is on track for global elimination. That is one hell of a legacy, but Hilliman didn’t finish there. He developed over 40 vaccines including those against influenza, mumps, hepatitis A and B, chickenpox, meningococcal, and Haemophilus influenza type B, How many more lives do these account for?
The infectious landscape in NZ is very different today than it was. Once upon a time, before air travel, if someone infectious got on a boat they had either died or recovered by the time they arrived here some 135 days later. New Zealand’s isolation made her a natural quarantine zone.
But in the end this did not stop the importation of infectious diseases and as more people came so did their diseases. The first documented outbreak of a now vaccine preventable disease was an influenza outbreak in 1817-20. From then on epidemics occurred regularly, decimating family sizes and disproportionality affecting Māori to the point where the population had halved by the late 1800s.
If one examines the chronology of events major enough to affect the health and size and life expectancy of the New Zealand population since 1850, it is striking how many of these are either infectious epidemics (negative effect) or the introduction of a vaccine (positive effect). (Editor’s note: the Statistics New Zealand website may be down due to 14 November earthquake).
The chronology starts with an influenza epidemic in 1852-3. In 1873 there was a notable pertussis epidemic with 356 deaths noted and the very next year a measles epidemic taking 344 children along with diphtheria killing 481 in the same year. These four diseases go on to appear as major events every few years. Today they are all preventable but still not curable.
A timeline of epidemics affecting New Zealand shows almost all of the most dangerous diseases (those that carried off the most people) are now be vaccine preventable. These diseases in order of first appearance in NZ were:
• 1817 Influenza
• 1835 Measles
• 1863 Scarlet fever, aka strep throat
• 1872 Diphtheria
• 1872 Smallpox (only the once in 1872)
• 1873 Pertussis
• 1874 Typhoid
• 1875 TB
• 1900 Plague
• 1916 Polio
• 1921 Meningitis (probably meningococcal disease)
• 1939 Rubella
• 1971 Hepatitis A
• 1983 HIV/AIDS
• 1997 Campylobacteriosis
• 2009 H1N1 swine flu
Most of these (with the exception of smallpox) caused repeated epidemics every 3 – 5 years until their respective vaccines were introduced. The bold ones are vaccine preventable to a greater or lesser extent.
While New Zealand never really suffered from smallpox, in part thanks to isolation, it was not until the introduction of the first national immunisation programme that sickness and death from these infectious stopped.
In 1926 the first vaccine was introduced into New Zealand. Diphtheria vaccine became available to schools and orphanages, but it was not until 1941 that it became routine for all children under seven years old. Below is what happened next:
The next cab off the vaccine rank to be introduced into New Zealand was Tetanus after 1940, however it was not until 1958 this became routine.
At this time we also began vaccinating against pertussis and the mortality rate plunged.
Polio vaccine arrived in 1956 and shortly after the disease was eliminated in New Zealand.
We have controlled these diseases through an effective immunisation programme which now reaches more of New Zealand’s children than ever before. In 1991 only about 56% of New Zealand children were fully vaccinated. This was a national shame, second from the bottom of all the OECD countries. Today we are awesome with around 94% of New Zealand children fully vaccinated against 11 diseases, soon to be 12. This puts us near the top of the OECD countries.
Twelve diseases we protect NZ children against before they are two years of age are:
- Haemophilus influenza type B (a cause of meningitis)
- Hepatitis B
- Pneumococcal disease
- Varicella (chickenpox) from 2017
In New Zealand, vaccines have not been universally embraced. People have forgotten what these diseases are and what they did to families.
Today myths about vaccines circulate widely on social media where opponents actively seek to discredit the vaccination programme. While falsehood flies around the world on Twitter in one second the truth can have a hard time catching up, and by then the damage has been done. Confidence in life-saving vaccines has been shattered through deceit.
The evolution of a vaccine programme is predicable. The Chen graph below may be old now, but it sums up the evolution of vaccine programmes beautifully. First there is disease. A vaccine comes along and the disease declines. People start freaking out about (usually perceived not real) adverse events and lose confidence in the vaccine. Coverage declines, disease comes back. People realise disease is bad and they should never have stopped vaccinating, coverage improves. Disease declines again.
I wonder what the families who watched their children die from these diseases would think about those that actively seek to prevent people immunising their children? An opportunity they never had.
Vaccines have changed people’s perception of what a normal life expectancy is. Today the single biggest threat to preventing these, and many more diseases, is a lack of commitment to and a lack of confidence in vaccines. Many people perceive vaccines to carry a much greater risk than they do. Despite the fact that vaccines are one of the safest public health interventions ever developed this is not always the perception.
Helen Petousis-Harris is a vaccinologist. Her background is predominantly biological sciences, and she did her PhD in vaccinology. She has an appointment as a Senior Lecturer in the Department of General Practice and Primary Health Care at the University of Auckland’s Faculty of Medicine and Health Sciences. She and has worked at the Immunisation Advisory Centre at the University of Auckland since 1998 where she has developed a passion for all things vaccine. Current focus of research is pertussis, pneumococcal disease, measles, meningococcal, HPV and gonorrhoea. Could be persuaded to turn attention to shingles.
This article was originally published on Te Punaha Matatini as part of InfectedNZ – an online campaign to raise awareness about infectious diseases and antimicrobial resistance. Read the original article.