The astonishing, life-saving power of immunisation

My daughter was just a few days old when she received her first vaccination. She was born in a part of London where the BCG vaccine was routinely given to newborns to protect them from tuberculosis. Holding her little body as the nurse prepared the vaccine, I vividly remember experiencing a whirlwind of conflicting emotions and thoughts.

As a medical researcher specialising in infectious diseases, I remembered the pictures from my university textbooks showing all the polio patients being kept alive by the “iron lungs” helping them breathe. I thought about all the studies I’d read showing just how safe and effective vaccines are. As a tuberculosis researcher I even knew what BCG stood for – Bacillus Calmette-Guérin – after the two researchers who developed the vaccine over a hundred years ago. I also knew that it was a version of the bacterium that causes tuberculosis in cows, and that it had been grown in the lab for over a decade until it could no longer cause disease. I even knew what genes it had lost in the process.

As an exhausted new mum, feeling pretty traumatised after an unexpected caesarean section, I didn’t want my new baby to experience any pain. I didn’t want her to have a fever, even though I knew that would be a sign her body was doing exactly what it needed to do to protect her.

I held her close as the nurse gave her the injection.

My daughter’s next few vaccinations were much easier. We had survived the first few difficult months of parenthood, and I was in a better place emotionally. My daughter was also easy to distract by offering her a feed. But when she was four and it was time for her booster shots, I knew we were in trouble. She wouldn’t be so easily distracted this time.

It started as soon as we arrived at the doctor’s surgery. Was I sick, she asked, with a look of real concern on her little face. She knew she felt fine so it must have been me, right? While we waited, I told her we were there because she needed to have a very special injection. I explained that it would feel a bit like a pin prick and that she might also feel a little hot and tired for a few days, but that I would look after her. I explained that the injection would help her body make special soldiers called antibodies so that if she met the nasty microbes that cause measles, mumps and rubella, her body would fight them off without her even knowing.

She asked what would happen if she didn’t get the “prickly”. I explained that if she caught one of those nasty microbes, she might get really sick. Would she die, she asked. I didn’t think so, I told her. But she might spread those nasty microbes to a young baby, or someone who was already sick, and they could end up in the hospital or die. We talked about how all people are precious and so caring for others meant that we got our “pricklies” to protect all the people who couldn’t get one.  

As a child of the 70s and 80s, I’ve no living memory of what life was like without the vaccines we now take for granted. Now we’re all living through a pandemic and can see for ourselves the local and global impact of not having a Covid-19 vaccine – yet. Before the pandemic, I immunised because as a microbiologist I study the ways in which bacteria can make us sick, bacteria for which there are no vaccines and which would be deadly without antibiotics. At the same time those antibiotics are rapidly losing their effectiveness because of antibiotic resistance. I know that many of these bacteria live up our nose or in our throat and can cause severe illness in children who catch measles or chickenpox.

But you don’t have to be a microbiologist to immunise.

Tanya immunises because she doesn’t want children to suffer like her Poppa did when he was hospitalised for months with polio as a four-year-old. Emily’s son Eddie is immune-compromised and if he caught measles there’s a 50% chance he would die. Having the MMR vaccine means he doesn’t have to face that risk. Many other people with underlying health conditions aren’t able to be immunised so rely on us to prevent the spread of diseases by being vaccinated. Children who are too young to be fully vaccinated also need our protection. Children like Whiti’s grandson who was just three weeks away from his first birthday when he caught measles. It took him months to recover.  

The power of immunisation

There are so many examples of how vaccines have helped us overcome what were once deadly infectious diseases. Take polio. It’s caused by the poliovirus and some infected people develop what’s known as flaccid paralysis, a neurological condition where muscles become weakened or even paralysed. For those patients who experienced flaccid paralysis enough to stop them being able to breathe, the solution was to put them in a sort of enclosed tank – the “iron lung”. Varying the air pressure in the tank helped them to breathe.

Before there was a vaccine, outbreaks of polio happened every few years in New Zealand with hundreds of cases. Schools and public spaces were closed, and in the worst years dozens of people were killed. In 1925 polio killed 175 New Zealanders. Then a vaccine arrived.

In 1956, we started using the Salk vaccine which was given by injection. Named after its developer Jonas Salk, the Salk vaccine was the poliovirus which had been chemically inactivated so that it was no longer able to cause disease. People needed two to three doses of the vaccine to become immune to infection. The impact of the vaccine was dramatic, with cases dropping from 897 in 1956 to 63 the following year.

In April 1962, a new polio vaccine was introduced around the world. This one, named after its developer Albert Sabin, was a live vaccine no longer able to replicate well within human cells. Unlike the Salk vaccine, the Sabin vaccine was able to be given orally rather than by injection, making it much cheaper and easier to administer. After it was introduced in New Zealand there were just 10 cases of polio between 1962 and 1977. After that, it was eliminated.

In 1988, the WHO, UNICEF, and Rotary started a global campaign to eradicate polio. Today the virus is naturally circulating in just two countries, Afghanistan and Pakistan.

It’s not just polio. Haemophilus influenzae type b (also known as Hib) is a bacterium that can cause meningitis, pneumonia, septic arthritis, and skin infections in children. In 1993, 101 children under the age of five had invasive Hib disease that meant they needed to be hospitalised. A vaccine was introduced in New Zealand in 1994. The following year, fewer than 10 children were hospitalised. In 2015 there were just two confirmed cases in children under five in New Zealand. Neither had been vaccinated.

The human papillomavirus causes genital warts and a range of cancers including cervical, throat, penile, and anal cancers. A vaccine was introduced in New Zealand in 2008. As cancer can take many years to develop, we can use genital warts to see how successful vaccination has been. From 2008 to 2019 genital warts clinical case counts reported by sexual health clinics have decreased by 79.5% (from 3,681 to 756 cases).

One of the most recent vaccines introduced in New Zealand protects against rotavirus, a highly infectious virus that infects almost all children during infancy or early childhood. While some children won’t have any symptoms, others can end up with severe diarrhoea and vomiting which can be life-threatening. After the vaccine was introduced in July 2014, the rates of rotavirus hospitalisations in children under three went from about 350 per 100,000 in 2014 to 50 per 100,000 in 2015. The number of outbreaks also fell, from 47 in 2014 to just three in 2015.

Community immunity

The data is really clear. Vaccines have saved countless lives. But the power of vaccination lies not just in the ability of vaccines to protect the people who are vaccinated but in the protective bubble they can cast over whole communities. Many important infectious diseases spread from person to person. When enough people in a community have been vaccinated, it reduces the number available to catch and then spread the infectious microbe to others.

This benefit of vaccination is often referred to as “herd immunity”. But I think the term fails to capture the commitment we’re making to more vulnerable members of society when we choose to immunise. It’s more powerful to think of it as community immunity.

Achieving community immunity does have its challenges. Some families in New Zealand have difficulties accessing healthcare, while others understandably don’t want to because of their experiences with systemic racism. We also need to tackle the abundance of fake vaccine information on social media and the internet. Let’s be clear: there is a huge amount of work that goes into ensuring the vaccines we use here in New Zealand are safe. We even have the Vaccine Safety Expert Advisory Group whose job it is to look into any unusual bad reactions people have to vaccines and to collaborate with international vaccine safety experts. You can find out more information about how vaccine safety is monitored here.  

Community immunity is really important, because there will always be members of our community who aren’t able to be vaccinated. Babies who are too young like Whiti’s grandson. Or people with underlying medical conditions which make vaccination potentially unsafe for them.

If Covid-19 has meant you or your family members have missed out on any of the routine vaccinations, don’t worry, for most of New Zealand’s immunisation programmes it’s not too late, so please talk to your GP as soon as possible.

You’re not just doing it for you, you’re doing it for all of us. For community immunity.

If you are after some good information on the different vaccines available in New Zealand, check out the Immunisation Advisory Centre’s website.