Types of Vaccines
Live vaccines are usually more potent than inactivated vaccines. They multiply within the host.health and fitness Updated: Oct 13, 2003 20:35 IST
Live vaccines are prepared from live organisms. These organisms are passed through chick embryos or other such media repeatedly till they lose their capacity to induce the disease fully, but retain the capacity to trigger off the defence mechanism.
Live vaccines are usually more potent than inactivated vaccines. They multiply within the host and produce more antigens.
Live vaccines should not be given to people with immune deficiency or people being treated for certain chronic ailments or pregnant women (unless absolutely necessary).
Live virus vaccines are used for tuberculosis ( BCG), measles and polio. Usually one dose of live vaccine is enough for immunity. Some, as in the case of polio, need more. These should be spaced out.
Effective storage is crucial for live vaccines. Do not receive vaccination from a centre that you suspect has poor storage facility.
Inactivated or Killed Vaccine
Certain organisms when killed by heat or chemicals and then introduced into the body induce immunity. Killed vaccines are not as effective as live vaccines.
For instance the pertussis vaccine, after three doses is about 80% effective in the first three years and after 12 years not at all. Inactivated vaccines may require two or three doses. These are administered by injections.
Diphtheria, pertussis, tetanus, cholera, rabies, and hepatitis B are some diseases that are combated with killed vaccines.
First Published: Oct 13, 2003 20:35 IST