ABSTRACT
Immunity is acquired in two ways. Active immunity follows exposure and stimulation of the immune response to any infection, such as the common cold and chickenpox, or by immunisation against hepatitis, measles, mumps and rubella (MMR). Passive immunity is short-lived immunity, occurring when immunoglobulins pass from the mother to the foetus across the placenta, from the mother to the baby in breast milk, or which are injected when immunocompromised children who have not been immunised are exposed to viruses such as measles (Simpson 1998).
