Vaccination and Immunisation
Vaccines help the body to recognise and fight viruses or bacteria by stimulating the immune system to produce antibodies to a specific disease. The term ‘vaccination‘ refers to the act of introducing a vaccine into the body to produce immunity to a specific disease.
Immunisation is a term used to define the process by which a person becomes protected against a disease through vaccination (this term is often used interchangeably with vaccination/ inoculation). Protection from an infectious disease gives you immunity (if you are immune to a disease, you can be exposed to it without becoming infected).
Vaccines are the most effective way to prevent infectious diseases. Vaccination coverage is the best indicator of the level of protection a population will have against vaccine-preventable communicable diseases. The World Health Organisation (WHO) recommends that on a national basis at least 95% of children are immunised against vaccine-preventable diseases (VPD).Click here for more.
They prevent up to 3 million deaths worldwide every year. Since the introduction of vaccines many infectious diseases such as smallpox, polio and tetanus that used to kill or disable millions of people have been eradicated or are seen very rarely. However, if people stop having vaccines, these infectious diseases can make a come-back and quickly spread again.
What are vaccines made of?
Vaccines contain several ingredients that may include a small amount of:
- a live, but weakened form of a virus
- killed bacteria or small parts of bacteria
- a modified toxin produced by bacteria
In addition, vaccines may also contain a small amount of:
- products that act as preservatives or stabilisers
- an antibiotic (to prevent bacterial growth)
- an aluminium salt which helps produce a better immune response.
For more information on composition of vaccines, click here.
How do vaccines work?
Vaccines teach your body’s immune system how to create antibodies to protect you from certain diseases. It is much safer for your immune system to develop antibodies this way as opposed to catching the diseases and trying to treat the potentially irreversible symptoms. Once your body can detect and fight a disease, the protection can last for many years.
What sort of protection do vaccines really offer?’
No medicine in the world is 100% effective, but vaccines are more effective than many other medicines (up to 99.7% in the case of the measles vaccine). Not all vaccines give lifelong protection (boosters may be required) and some individuals may be better protected than others. However, there are several things to consider, such as:
- Catching a disease does not always give you 100% immunity either. It is possible to catch some diseases such as tetanus, rubella, whooping cough and meningococcal disease more than once.
- If most of the population is vaccinated, this raises protection for everyone to almost 100%. This is referred to as ‘herd immunity‘.
- If someone who has been vaccinated in the past catches a disease, the symptoms are generally milder than they would be for a person who has not been vaccinated against that disease.
How are vaccines administered?
Vaccines are usually administered through injections into the muscle of the arm or thigh, but can also be administered by mouth or sprayed into the nose.
Are vaccines safe?
Yes. The safety of a vaccine has to be thoroughly tested and determined before it is licensed. Safety continues to be monitored on a global scale whilst in use. Research from around the world shows that immunisation is the safest way to protect your child’s health. You are far more likely to be seriously injured or permanently disabled by a vaccine-preventable disease than by a negative side-effect of a vaccine. For example, a rare an serious effect of measles infection is Subacute sclerosing panencephalitis (SSPE). Click here to view video.
How long does immunisation against a disease last?
An unborn baby gets some antibodies from the mother through the placenta. This type of immunity is called passive immunity. The amount and type of antibodies passed to the baby depends on the mother’s immunity. For example, if the mother has had chickenpox, she will have developed immunity against it and some of the chickenpox antibodies will be passed to the baby. On the other hand, if the mother has not had chickenpox, the baby will not be protected.
It is important to note that immunity in newborn babies is only temporary and starts to decrease after the first few weeks or months. Infants’ immune systems are not fully developed until they are about six months old; making them more vulnerable to infections and diseases than adults. A timely vaccination regime is necessary to prompt infants to start to produce antibodies within their own bodies.
The recommended timing of vaccination for each disease aims to provide the best immune protection for the period in life when vulnerability to the disease is highest. It is best for babies to be vaccinated at the recommended age, as they are then protected from serious diseases as early in life as possible.
Does immunisation last forever?
The duration of immunity varies with different diseases and different vaccines. Some immunisations have to be given more than once to build up immunity (protection) or keep the level of antibodies topped up. This ‘top up’ is called a booster.
Are there any reasons why children should not be immunised?
There are very few reasons why a child or adult should not be immunised.including:
- a high fever
- has had a bad reaction to another immunisation
- has had, or is having, treatment for cancer;
- has a bleeding disorder
- has had a severe reaction after eating eggs (as the MMR is prepared in egg)
- has had convulsions (fits) in the past.
You should also notify your health visitor, nurse or GP, if you or any close family member:
- has any illness which affects the immune system (e.g. HIV or AIDS)
- is taking any medicine which affects the immune system (e.g. immunosuppressants) or high-dose steroids.
How will I feel after immunisation?
All people are different and react differently. Most peopel will not be affected after a vaccination. Sometimes redness and swelling may develop at the site of the injection, but it will slowly disappear. Few individuals may feel unwell or irritable and may develop a temperature.
Very rarely are may be an allergic reaction straight after immunisation. Should this occur, people administering the immunisations are trained to deal with allergic reactions.