How vaccines work
What is a vaccine?
Pathogens are microbes such as viruses or bacteria that cause disease. Vaccines include a small amount of weakened or harmless microbe, which when introduced into the body stimulates the immune system to produce antibodies.The immune system is then able to remember the microbe so if the body is invaded by the real pathogen, it is able to fight it instantly and stop the disease developing. With some vaccinations, the immune memory can reduce over several years, which is why booster vaccinations are needed.
When were vaccines discovered?
The term vaccination is derived from ‘vacca' which means cow in Latin and was the name given to the first successful vaccine to be developed in 1796 by Edward Jenner from Berkeley, Gloucerstershire. His inoculation with the cowpox virus gave humans protection against the deadly scourge of smallpox - one of the most contagious and deadly diseases known to man.
As a country doctor, Jenner had always been fascinated by the old wives tale that milkmaids could not get smallpox and believed there was a connection between the fact that they only got cowpox - the non-life threatening weak version of smallpox - but not smallpox itself.
Jenner tried out his theory by vaccinating a healthy young boy with the virus from a dairymaid who had contracted cowpox. The boy proved Jenner's point by surviving repeated attempts to infect him with smallpox.
How do vaccines work?
Pathogens are microbes such as viruses or bacteria that cause disease. Vaccines include a small amount of weakened or harmless microbes, which when introduced into the body stimulate the immune system to produce antibodies.
Vaccines can be made in a variety of ways such as from inactivated (killed) or attenuated (weakened) live organisms or from parts of the bacteria's cell wall. For example the pneumococcal vaccine contains the polysaccharide (carbohydrate) from the cell wall of the pneumococcus bacteria. Some vaccines such as the Hib and Meningitis C vaccines are improved by ‘conjugation' where the polysaccharide outer coat is combined with a protein, which enables the immune system to give a broader response to the invading bacteria.
The immune system is then able to remember the microbe so if the body is invaded by the real bacteria, it is able to fight them instantly and stop the disease developing. With some vaccinations, the immune memory can reduce over several years, which is why booster vaccinations are needed.
Do vaccines exist to protect against meningitis?
Vaccines exist to protect against several of the common forms of meningitis such as Hib, Meningitis C and pneumoccoccal meningitis. All of these vaccines are offered to children and other high risk groups through the routine UK immunisation schedule. Individuals who are not vaccinated will still benefit from the routine vaccination programme as those who have been vaccinated are less likely to be a source of infection - this is called herd immunity.
However, there is still no vaccine to protect against the most common form of bacterial meningitis in the UK, Meningitis B and other forms such as Streptococcal Group B. It is also very important that impact of existing vaccines and closely monitored and that improvements are made, Meningitis UK is currently funding research in these areas.
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