The importance of vaccine education

In the last 50 years, vaccines have saved over 154 million lives – that’s six lives every minute! Many illnesses that used to affect millions of people, such as polio and diphtheria, are now almost unheard-of and smallpox, previously one of the world’s deadliest diseases, has been eradicated completely. 

But despite the effectiveness of vaccination, recent years have seen a rise in mistrust of vaccines. This has led to a decrease in vaccination rates, causing a resurgence of many diseases. This is why health educators Dr Constance Blomgren, Dr Karen Cook and Dr Stella George are on a mission to increase vaccine confidence.

“Many factors influence vaccine decision-making,” says Karen. “Cultural, social and political factors all play a part, as well as the characteristics of individuals and their groups, and the specifics around particular vaccines themselves.” Getting vaccinated is an individual choice, but it is also a social responsibility. As many diseases are contagious, an individual’s vaccine choice can affect the health of others. By getting vaccinated, you are not only protecting yourself from disease but also potentially protecting those around you, by preventing yourself from passing the disease on to them.

Some people who were vaccinated against COVID-19 still went on to acquire the disease, but this does not mean that the vaccine doesn’t work. As an immunologist, Assistant Professor Aimee Pugh Bernard uses the analogy of seatbelts to explain the function of vaccines – you don’t wear a seatbelt in a car to prevent yourself from getting into a crash. However, if you do end up in a crash, your chance of survival will be dramatically higher if you were wearing a seatbelt. The same goes for vaccines: “While a vaccine may not prevent a ‘crash’ (i.e., an infection), it is a safety tool that prevents serious harm and death,” explains Aimee.

How does the immune system work?

Your immune system is the complex network of cells and biological systems that protects you from diseases. It is made up of two parts, the innate and adaptive immune systems, which work together to combat infections. “As an analogy, you can think of these two parts of the immune system as a combination of the transportation security administration (TSA) at the airport and more advanced security units,” says vaccinologist Professor Ross Kedl. “The TSA officers are very good at detecting possible threats from people or baggage. If a threat is detected, the TSA officers initiate containment efforts, such as closing the airport or grounding planes, then they pass along the information to the police or military, who can devise a specific plan of attack for the threat at hand.” Like the TSA officers, our innate immune system alerts the body to threats from pathogens (disease-causing microbes), before passing control over to the adaptive immune system, which provides a more specialised and targeted response.

Armed with this knowledge, vaccinologists take advantage of our immune system to develop vaccines that protect us from pathogens. Adaptive immune cells learn to recognise specific pathogens, so if you are reinfected, your adaptive immune system will remember how to defend you. Vaccines deliver a dead or weakened pathogen, or a molecule derived from the pathogen, into the body so the immune system learns how to fight the infection.

Vaccinating against viruses hiding in our cells

“It is estimated that over 70% of the world’s population is infected with human cytomegalovirus,” says virologist Dr Matthew Reeves. Yet most people will carry this herpes virus throughout their lives without ever noticing, as it usually only causes mild symptoms that feel like a bad cold.

Once a person is infected with a herpes virus (such as glandular fever, cold sores or chicken pox), they are infected for life, as herpes viruses have evolved to evade detection by the immune system. This means the virus resides in the body in a ‘latent’ form where it doesn’t cause any harm, although the immune system must constantly work to control the virus. But if someone’s immune system becomes weakened, then they won’t be able to supress any latent viruses in their body. This is why some people suffer from repeated bouts of glandular fever each time they become overly tired and run down, why people develop cold sores if they become stressed, and why adults can develop shingles decades after they had chickenpox as a child. In each case, the latent herpes virus is reactivating because the weakened immune system can no longer control it.

And while human cytomegalovirus only causes cold-like symptoms in most people, it’s a serious condition for people without a functioning immune system, including unborn babies and organ transplant patients, which is why Matthew hopes to develop a vaccine to protect us from the potentially harmful effects of this virus hiding in our cells.

Preventing deadly diseases

Malaria (caused by a parasite spread by mosquitos) is one of the world’s deadliest diseases, killing hundreds of thousands of people every year. “It’s estimated that malaria has caused 50% of all human deaths since the Stone Age,” says Professor Richard (Rick) Bucala. “Even with today’s anti-malarial drugs and mosquito control strategies, malaria remains the world’s second leading cause of death by infectious disease.”

Scientists have been trying to develop a malaria vaccine for decades, but the nature of the disease means it hasn’t been an easy task. Early attempts taught the immune system to recognise a particular protein on the malaria parasite. However, these vaccines were not very effective as the protein varies between different strains of parasite and can mutate through time. To combat this challenge, Rick and his team took a different approach and developed a vaccine based on RNA rather than protein.

Vaccinating against cancer

We might think that vaccines are used for protecting us from infectious diseases, such as COVID-19. However, scientists are also exploring how vaccines can prevent cancer. Immunologist Dr Zachary Hartman is examining how the gene that makes some breast cancers very aggressive can be used in a vaccine to protect against breast cancer. The idea is that the vaccine would stimulate immunity against this gene, however as the gene is also present in healthy breast cells, Zachary’s challenge is to ensure that the vaccine-generated immunity only targets cancer cells. In his initial trials, his vaccine was shown to successfully trigger specific immune responses in most patients, paving the way for the development of new cancer treatments.

The importance of vaccinating animals

Many viruses that infect humans originally infected animals, the most famous examples being COVID-19 (the jury is still out as to whether the culprit was a bat, pangolin or racoon dog), HIV (from chimpanzees), swine flu (from pigs) and bird flu (from birds).

Another example is Nipah virus, which is found in fruit bats in Southeast Asia. The virus can be transmitted from wild bats to farmed pigs, where it produces mild symptoms making it is hard to diagnose. But it can then be transmitted from pigs to humans, where it becomes much more dangerous. Initial symptoms in humans include fever and breathing difficulties, followed by brain swelling leading to a coma and, in 45% to 75% of cases, death.

Nipah virus was first identified in pig farmers in Malaysia in 1998. To contain the outbreak, over a million pigs were slaughtered which devastated the country’s economy, and, to this day, pig farming is still banned in many parts of Malaysia. It would be impossible to vaccinate wild populations of fruit bats, so vaccinologists Dr Rebecca McLean and Professor Simon Graham are developing a vaccine to prevent the spread of Nipah virus in farmed pigs.

As these researchers have shown, vaccines have the power to save lives, improve health and protect society. Learn about the fascinating history of vaccines from the World Health Organisation: who.int/news-room/spotlight/history-of-vaccination/a-brief-history-of-vaccination

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