Immunity is the state or quality of being immune. Immunity is referred to as the resistance exhibited by the host towards an injury caused by a microorganism and its products.
Types of immunity.
- Innate (inborn) immunity: which are genetic factors;
- Acquired immunity: which is sub-divided into;
- i) Active (own antibodies). We have natural active immunity and artificial active immunity through immunization.
- ii) Passive (ready-made antibodies). There is natural passive immunity from maternal antibodies and artificial passive immunity from other sources.
A few details about the types of immunity
- Active immunity occurs when our immune system response to an infection (natural immunity) or a vaccine (vaccine-induced immunity). This leads to a potent immune response involving all the components of the immune system and it establishes memory immunity. Active immunity tends to be robust and long-lasting. In the case of vaccination, this can be lifelong.
In contrast passive immunity is a transfer of immune system components from one individual to another. This can be natural or artificial.
Artificial passive immunity is transferring or injecting immunoglobulin’s (antibodies) into a person. This is mostly seen when treating a person with snake bite with antivenom.
Natural passive immunity is the transfer of antibodies during pregnancy via the placenta to the fetus or during nursing via the breast milk. This offers some benefits to the baby, as antibodies can help protect against infection while a baby’s immune system is developing and when they aren’t able to get vaccinated themselves.
However, passive immunity does not involve the cells of the immune system that are required to mount long- lasting immunity. This means passive immunity is only temporal, lasting for weeks to months, until the antibodies degrade. For nursing babies or newborns, passive immunity can offer some temporary protection when they are their most vulnerable.
The table below shows the difference between Active and Passive Immunity