Immunisation is the approach by which a person’s immune system is protected against a foreign agent. Immunisation makes use of the body’s natural protection mechanism – the immune response – to develop resistance to particular infections. ‘Immunisation’ is the term used for the approach of acquiring the vaccine and to immunize the disease as an effect of the vaccine. A vaccine is a biological preparation that enhances immunity of a specific disease. A vaccine generally consists of an agent that is similar to a disease-triggering microorganism and is generally made from weakened or killed forms of the microbe, its toxins or one of its surface proteins. The agent influences the body’s immune system to identify the agent as foreign, kill it, and keep a record of it, so that the immune system can quickly identify and kill any of these microorganisms that it can later incur.

Why should people be immunised? Immunisation is the most secure and most effective way of providing protection towards any disease. After immunisation, children are far less probable to get the disease if there are cases in the community. The advantage of protection against the disease far exceeds the very small threats of immunisation. If enough individuals in the community are immunized, the infection can no longer propagate from one individual to another individual and the disease dies out completely. This is how smallpox was removed from the world, and polio has vanished from many nations.

Significance vaccine development: Vaccine development for life frightening diseases like Malaria and HIV can save millions of people’s life globally. Malaria is second major cause of death of children in Africa, killing almost one million kids each year. Every day 3,000 kids die from the disease.  The Centers for Disease Control and Prevention (CDC) has reported that malaria is the fifth major cause of death from infectious diseases globally (after respiratory infections, HIV/AIDS, diarrheal diseases, and tuberculosis). Malaria is the 2nd major cause of death from infectious diseases in Africa, following HIV/AIDS.

HIV is the major cause of deaths in Africa and 3rd leading cause of deaths from infectious diseases worldwide. Tanzania is one of sub-Saharan African nations which are ruined by the HIV/AIDS epidemic. The epidemic was identified in Tanzania in 1983 and by December 1986 all areas had reported minimum one case. Females have more impact than males at a ratio of 1.22 i.e. where 122 females are infected, 100 males are infected. Urban residents have greater risk of HIV infection than rural residents. In accordance to outcomes from the recent Tanzania HIV/AIDS Indicator survey, HIV occurrence among adults aged 15 – 49 years is 7% while the occurrence among females and males of that age group is 7.7% and 6.3% correspondingly. Therefore it is very important to develop vaccines which can protect the people from life threatening infectious diseases.