Do you know that smallpox vaccine is made from inactivated smallpox viruses?. Do you know that polio vaccine is composed of inactive polioviruses?.
Get to know WHY inactive form of microorganisms is used in vaccinating against infections by visiting the link below, You will love it!.
Immunization is the artificial induction of immunity on an individual. This can either be through active or passive means. The last week of April (usually 24-30th of April) is usually dedicated for immunization (often referred to as world immunization week)
Active immunization is the stimulation of the immune system to protect individuals against disease through the use of vaccine.
Passive immunization is the stimulation of immunity on a non-immune individual by administering sensitized lymphoid cells or serum from immune in individuals
History has it that the Chinese and the Turkish were able to reduce the rate of mortality to smallpox among their population through inoculation (whereby scabs from infected individuals were blown through the nostril of healthy individuals to prevent them from getting infected with smallpox). The idea of inoculation of healthy individuals with scabs from infected individuals was introduced to England by Lady Mary Wortley Montagu, the wife of a British ambassador to the Ottoman Empire. Edward Jenner, a British physician observed that people that were previously infected with cowpox were resistant to smallpox infection. In May 14, 1796 he extracted the fluids of pustule from a milkmaid named Serah Nelmes who had been infected with cowpox and injected it into 8-years old James Phipps and observed for symptoms. On the seventh day, he complained of mild cold and a slight headache and recovered completely the following day. Six weeks later, James Phipps was inoculated with extracts from smallpox pustule. The boy showed no symptom of smallpox. He had been completely immune against smallpox. This birthed the beginning of modern-day vaccination. This delightful discovery became a step stool for the discovery of Anthrax, Cholera and Rabies vaccine by Louis Pasteur and many other discoveries by other scientists in the field of medical microbiology.
Types of vaccines
There are two (2) type vaccines:
- Inactivated vaccines
This type of vaccine is composed virulent microorganisms made ineffective by either chemicals or irradiation.
- Attenuated vaccines
Vaccines are produced from virulent microorganisms grown under adverse conditions are passed through different host until they become avirulent.
Examples of vaccines
The Table Below Shows Bacteria/Viral Agents And Their Vaccines To Prevent Diseases In Humans:
|varicella zoster virus (Chicken pox virus)||Varivax (Attenuated Oka Strain)|
|Hepatitis A virus||Havrix (inactivated virus)|
|Hepatitis B virus||Engerix- B, Recombinant HB (HB viral antigen)|
|Influenza A virus||Inactivated/ live attenuated virus Influenza A virus|
|Poliovirus||Attenuated polio virus|
|Rabies virus||Inactivated rabies virus|
|Smallpox virus||Live attenuated smallpox virus|
|Yellow fever virus||Attenuated Yellow fever virus|
|Bacillus anthracis (causal agents of Anthrax)||Extracellular components of un-encapsulated B. anthracis|
|Vibrio cholerae (Cholera)||Fraction of Vibrio cholera|
|Clostridium tetani (causal of Tetanus)||Tetanus toxoid|
|Yersinia pestis (causal of Plague)||Fraction of Yersinia pestis|
|Mycobacterium tuberculosis (Causal of Tuberculosis)||Attenuated Mycobacterium bovis (BCG)|
|Salmonella typhimurium (Typhoid fever )||Attenuated Salmonella enterica Typh Ty21a|
|Rickettsia prowazekii (Typhus)||Killed Rickettsia prowazekii|
HOW THE BODY BECOME IMMUNE TO DISEASE AFTER VACCINATION
Immunity via vaccination is enhanced by B-Cells. When inactivated or attenuated vaccine (composed of weakened infectious agents) is introduced into the body of an unhealthy individual. The humoral immunity mediated by antibodies takes charge. The antibodies which are produced by the B- cells opsonize the target infectious agent (weakened) and present it to T- cells, macrophages that eliminates the bacteria and viruses.
It should, however, be noted that Memory B cells and Memory T-Cells keep long term information pertaining to the vaccine (weakened bacteria/ virus) introduced into the body.
When the body encounter live (active) of such virulent bacteria or virus, the Memory B- cells and T- cells initiates the body to quickly produce antibodies that quickly help to eliminate such infectious agent when the infected person showing symptoms. Thus immunity is conferred vaccinated individuals.
DEFINITION OF TERMS
Vaccine: a preparation containing weakened or dead microbes of the kind that cause disease, administered to stimulate the immune system to produce antibodies against that disease
Virulent: pertaining to highly pathogenic or infectious microorganism.
Avirulent: pertains to an un-infectious microorganism
TOXOID: modified toxin from a pathogenic microorganism, which is no longer toxic but is still antigenic and can be used as a vaccine
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