Until the twentieth century, infectious diseases were the leading cause of death and disability worldwide, and this is still the case in much of the developing world. Immunisation has played a central role in radically reducing the incidence of many dangerous diseases, and some diseases have been wiped out entirely (e.g. smallpox), or are well on the way to being so (e.g. polio). Vaccines have saved many lives, and will save many more in the future, as new vaccines are developed giving protection against more diseases (see Vaccines in Development).
This infographic from Public Health England shows the impact that vaccination has had on infectious diseases in the UK.
What vaccines are available?
In the UK, the following vaccines are routinely offered free of charge by the NHS:
- 5-in-1 DTaP/IPV/Hib Vaccine
- Rotavirus Vaccine
- Pneumococcal Conjugate Vaccine (PCV)
- MenB Vaccine
- Hib/MenC Vaccine
- MMR Vaccine
- Nasal Flu Vaccine
- Pre-school Booster
- HPV Vaccine
- Teenage Booster
- MenACWY Vaccine
The following vaccines are offered free of charge to people in particular risk groups:
- Hepatitis A Vaccine to protect people who are at risk from Hepatitis A Infection
- Hepatitis B Vaccine to protect babies and other people who are at risk from Hepatitis B Infection
- Chickenpox (Varicella) Vaccine to protect contacts of people who are at risk from chickenpox infection
- TB (tuberculosis) vaccine (the BCG vaccine) to protect those who are at risk from TB infection
How does vaccination work?
Infectious diseases are caused by tiny organisms called pathogens (or germs) – some are bacteria, others are viruses. The human body has natural defences against these in the form of white blood cells, but in many cases pathogens can overwhelm the body before it has a chance to respond, causing disease and sometimes death.
Vaccines work by imitating a specific disease, which prompts the body to mount a defence (an immune response). Some of the white blood cells formed in this process remain in the body for a period of some years. If the same pathogens enter the body during this period, the body can attack them very quickly and the disease will not develop: the person will be immune.
The British Society for Immunology has a good introduction to how the immune system works .