There are good reasons why we should vaccinate children, Dr Joanna Kirman and Prof Sarah Hook write.
At 14 months, most toddlers are learning to walk and use their first words. But for New Zealand author Shirley Hazlewood, this was the age when she contracted the potentially deadly disease, poliomyelitis (polio).
Instead of playgrounds and parks, her early childhood was spent in hospital, and although she survived she has been left with a lifelong disability.
Between 1916 and 1956, New Zealand experienced seven polio epidemics, afflicting thousands of young children and adolescents. Hundreds of previously healthy young New Zealanders died from this devastating paralytic infectious disease.
Nowadays, polio is an unfamiliar word to many of us, thanks to a global effort that achieved high enough immunisation rates to eliminate polio from New Zealand and most other countries.
Unfortunately, polio still exists in a handful of countries, where vaccination rates are much lower. When vaccination rates have fallen too low, polio has reared its ugly head in countries previously declared polio-free.
In order to successfully eliminate or reduce infectious diseases, it is critical most of the community is vaccinated. The World Health Organisation recommends 95% of a population is fully vaccinated.
If too few people are vaccinated, infections can spread easily throughout the community. Within any population, there will be some children or adults who are especially vulnerable.
The immune system is like a miniature army that protects us from infection. Some people naturally have a small, poorly outfitted army with limited capability; most have armies with the potential to become large and well-equipped. Good nutrition and a healthy lifestyle can help the immune army, but only to a limited extent.
Most immune armies can fight off a weak infectious enemy, but only a strong well-trained army can wage war against a multitude of menacing infectious enemies.
There are two main ways to support the immune army to protect against infection.
The first is vaccination: this will educate and equip your army in the best possible way. Your immune army will develop more highly skilled soldiers with the best weaponry suited for the infectious enemy.
The second is support from the armies of others who have already been vaccinated. This is known as ''herd immunity'' and allows us to protect babies (whose armies only have a few new recruits with poor equipment) and others who naturally have weak armies (for example those with inherited immune-deficiencies, or the elderly).
Herd immunity is effective when enough people in the community are vaccinated. If enough people have good armies the enemy is unable to establish itself in the population - it cannot spread and therefore it is less able to attack those with weak armies.
Choosing not to vaccinate a baby not only puts that unvaccinated child at risk, but can endanger the lives of others.
Many parents are concerned over the safety of vaccines. Such concerns have been brought to attention by the recent screening of the film, Vaxxed, on the University of Otago campus.
This film does not in any way reflect the views of scientists and clinicians at the university. Rather, scientists and clinicians rely on vaccine safety data that has been generated by reputable organisations in large-scale, well controlled studies.
These studies undergo a peer-review process, in which other research experts evaluate the methodology and interpretation of data. It is a dynamic process, and if data are later found to be incorrectly generated or interpreted then these studies can be retracted or corrected data supplied.
Vaccines need to have strong evidence of their safety and effectiveness before inclusion to the immunisation schedule.
We are fortunate today that most parents will not have to witness the horror of their newborn baby struggling to breathe with whooping cough. However, because we no longer bear witness to these frightening diseases, it is easy to forget the danger. This makes it difficult to recognise the benefits of vaccination.
If vaccination rates drop, outbreaks of disease in our children will become more commonplace, such as the 2015 outbreak of whooping cough in Hawea and the recent measles and mumps outbreaks in the North Island.
We should not make the mistake of assuming vaccine-preventable diseases such as measles, mumps and whooping cough are not serious. In some children, measles causes encephalitis (swelling in the brain) that can lead to life-long disability or in the worst cases, death. These diseases can be prevented in even our most vulnerable by maintaining high vaccination levels in our community.
We cannot risk complacency.
-Dr Joanna Kirman works in the department of microbiology and immunology and Prof Sarah Hook in the School of Pharmacy at the University of Otago.
