Vaccines are one of the most effective public health interventions in history, saving billions of lives since the first vaccine was produced in 1798. The World Health Organization (WHO) estimates that vaccines prevented at least 10 million deaths in just five years between 2010 and 2015 alone. So how exactly do they work?
At any time, there are trillions of bacteria and viruses on or inside the human body – not all of which can cause disease. When disease causing bugs (such as, bacteria, viruses, fungi or parasites, for example) do get into the body, however, our immune system recognises them as “intruders” and works to protect us by producing antibodies. Antibodies stick to and kill or disable the harmful bug. This process takes time, as your body tries to produce the right antibody for the intruder, during which you may become very unwell – even die.
However, once your body has developed successful antibodies, they remain in the bloodstream. This means that if particular bug returns, your body can react immediately to fight it. Vaccines are based on this natural defense mechanism to help protect us against some of the world’s deadliest diseases.
Vaccines work by introducing small, harmless amounts or fragments of the bugs which cause disease, which are dead, weakened or inactive, into your system. This “tricks” your immune system into developing protective antibodies. Then, if the “real” version of that intruder ever gets in, your body already has the antibodies it needs to neutralise it – often before you even notice.
Vaccines are available to protect against many diseases, including:
- Cervical cancer
- Hepatitis B
- Yellow fever
Is this process safe?
Yes. Vaccines are thoroughly tested and are the safest way to develop protection against some common causes of deadly disease. As with all drugs, vaccines can cause side effects such as soreness/redness at the injection site in some people, but any vaccine that is given to a child or adult is rigorously tested and monitored for safety, to ensure that the benefits outweigh any risk.
The overwhelming evidence shows that vaccinating is safer than not vaccinating.