Vaccines and vaccination
Vaccinations give protection against specific diseases, but the level of protection in a population depends on the proportion of people vaccinated.
Microorganism that causes disease. are microbes that cause Illness affecting plants and animals.. Substances containing disabled antigens of a particular disease, usually administered via injection. Vaccines stimulate the body to produce antibodies to provide immunity against that disease. contain a dead or altered form of the disease-causing pathogen, which is introduced into the body. These dead or altered pathogens carry a specific A protein on the surface of a substance (often a pathogen) that triggers an immune response.. This causes the immune system, specifically the A type of cell found in blood that defends against infection., to produce complementary A protein produced by the immune system in humans (and other animals) that attacks foreign organisms (antigens) that get into the body., which target and attach to the antigen.
The body has two kinds of white blood cells which work together to destroy the pathogens.
- The first kind of white blood cell makes antibodies which cause the pathogens to clump together.
- The second type of white blood cell second destroys the pathogen by engulfing and digesting it. This process is also called The process of the ingestion of bacteria or other material by phagocytes..
The white blood cells which make antibodies remain in the body afterwards. These are called White blood cells (lymphocytes) that remain in the body after the immune response to an infection has finished. They reproduce rapidly if the body is re-infected, producing a faster and greater immune response.. They enable a more rapid and larger build-up of antibodies following a second exposure to the pathogen.
During the The first time an organism becomes infected by a particular pathogen. the antibodies slowly increase, peak at around ten days and then gradually decrease. A second exposure to the same pathogen causes the white blood cells to respond quickly in order to produce lots of the relevant antibodies, which prevents infection.
The problem with mutation
Some vaccinations last longer than others, so new vaccines need to be developed regularly. This is because the DNA of some pathogens mutates frequently, while others do not change. Once you are fully vaccinated against measles, you will be protected for at least 20 years. However, the influenza viruses' DNA mutates frequently, producing new antigens. The memory cells will not recognise this year's new strain of flu, and so a different vaccination is needed each year to give immunity.
Victory over smallpox
Vaccination wiped out smallpox. In 1967 there were 10 to 15 million cases of smallpox worldwide. That year WHO began a campaign to vaccinate people all over the world. The last natural case of smallpox was recorded in Africa in 1977.