Immunisation and vaccines work by imitating an infection or disease and stimulating the immune system to develop antibodies.
Antibodies are the body's way of protecting us against disease or infections.
The antibodies produced by vaccines fight disease without actually infecting us with the disease.
If a vaccinated person comes into contact with the disease, their immune system will recognise it and immediately produce the antibodies they need to fight it.
Newborn babies are protected against several diseases, such as measles, mumps and rubella, because antibodies have passed to them from their mothers. This is called passive immunity. Passive immunity usually only lasts for a few weeks or months.
Immunisation and vaccine ingredients
Immunisations and vaccines are made using viruses or bacteria and weakening or inactivating (killing) them so they cannot replicate or trigger disease. They need additives to improve the way they work, increase their shelf life, and make them as safe and effective as possible.
The 3 main substances added to vaccines are:
- adjuvants or enhancers – to make the vaccine more effective
- stabilisers – to stop the vaccine deteriorating when it's exposed to changes in the environment, such as light and temperature
- preservatives – to increase the vaccine's shelf life
Find more detailed information about vaccine ingredients.
Number of vaccine doses
Some vaccines require a course to give best protection. For example, measles, mumps and rubella (MMR) requires 2 doses, whereas other vaccines can be given as a single dose.
Vaccination programmes
When a vaccination programme is introduced, everyone of a certain age or in a certain risk group is offered a specific vaccine to try to reduce the number of cases of the disease.
Vaccination programmes aim to protect people for life. They often concentrate on young children as they're at risk of many potentially dangerous infections.
Some vaccination programmes are for older people, such as the shingles vaccine.
Other programmes are for certain risk groups, such as whooping cough vaccine for pregnant women.
When a vaccination programme against a disease begins, the number of people catching the disease goes down.
But it's important to keep vaccinating, otherwise the disease can spread again. If enough people in a community are vaccinated, it's harder for a disease to pass between people who have not been vaccinated. This is called "herd" or population immunity. Herd immunity is particularly important for protecting people who cannot get vaccinated, such as those having treatment that damages their immune system.
In Jersey, because our diseases patterns are similar to those in the UK, we follow the expert advice of the UK Joint Committee on Vaccination and Immunisation (JCVI). We try, wherever possible, to offer the same vaccinations as are advised by JCVI for the recommended groups of people.
For more information about Jersey vaccination schedule.
Vaccines help the immune system
As soon as a baby is born, they come into contact with large numbers of different bacteria and viruses every day. Their immune system is designed to cope with this.
But some diseases can overwhelm the immune system and cause harm, or even kill.
Vaccination helps to improve protection against life-threatening diseases at the right time.
A child's immune system is not overloaded by the childhood vaccination programme. Studies have shown there are no harmful effects from giving several injections of vaccines at the same time.
The bacteria and viruses used in vaccines are weakened or killed, and there are far fewer of them than the bugs that babies and children come into contact with every day.
Getting rid of disease
As more people are vaccinated, the disease can sometimes disappear completely and the vaccination programme can be stopped. This has happened with smallpox.
If a disease is highly infectious, more people will have to be vaccinated against it to keep the disease under control.
Measles, for instance, is highly infectious. If the number of people who have MMR goes down, measles will quickly spread again.
We know at least 90% of children have to be immune to stop a disease spreading. If 95% of children are protected by MMR, it's possible to get rid of measles.
Benefits of vaccination
Vaccination offers prevention rather than cure.
Vaccination helps to prevent the transmission of, and long term protection against infectious diseases. They are particularly important against infectious disease for which there may be no effective treatment, or which are becoming increasingly difficult to treat because of antibiotic resistance.
Vaccination is different from giving medicine to an unwell child to make them better. The benefits of vaccination are invisible.
The idea is that your child will not become ill with measles or end up in intensive care with meningitis.
It may be tempting to say "no" to vaccination and "leave it to nature". But deciding not to vaccinate your child puts them at risk of catching a range of potentially serious, even fatal, diseases.
In reality, having a vaccination is much safer than not having one.
Immunisations and vaccines are thoroughly tested for safety before they're made routinely available.
Each vaccine's safety is continually monitored, even after it's been introduced.
Vaccines are not 100% effective in every child, but they're the best defence against the epidemics that used to kill or permanently disable millions of children and adults.
Risk of vaccine side effects
All medicines have side effects. But vaccines are among the safest, and the benefits of vaccinations far outweigh the risk of side effects.
When you're considering a vaccination for yourself or your child, it's natural to focus on the potential side effects.
A better approach is to try to balance the benefits of having a vaccine against the chances of harm. Most side effects from vaccination are mild and short-lived.
Common side effects
It's quite common to have redness or swelling around the injection site, but this soon goes away.
Younger children or babies may be a bit irritable or unwell, or have a slight temperature. Again, this usually goes away within 1 or 2 days.
Find more detailed information about the common side effects of vaccinations in babies and children up to 5 years of age.
Rare side effects
In much rarer cases, some people have an allergic reaction soon after a vaccination.
This can be a rash or itching that affects part or all of the body. The GPs, nurses and pharmacists who give vaccinations are trained in how to treat this.
On very rare occasions, a severe allergic reaction may happen within a few minutes of the vaccination.
This is called an anaphylactic reaction. It can lead to breathing difficulties and, in some cases, collapse. Remember that anaphylactic reactions are extremely rare (less than 1 in a million).
Vaccination staff are trained to deal with this, and these reactions are completely reversible if treated promptly.
Find out how to report a side effect of a vaccination via the yellow card scheme.
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