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AEFI- Adverse Events Following Immunization

Adverse Events Following Immunization

The two major aspects of any intervention are its effectiveness and safety.Side effects, or adverse reactions, or adverse event, occur with practically every drugs / medicine.  In case of immunization there are two important differences compared with other drugs. 

  1. Vaccines are given to healthy individuals, therefore, the tolerance for adverse reactions is much lower. 
  2. Vaccines are generally given to a large number of individuals.   Therefore if an adverse reaction does occur infrequently, a large number may be seen.  Chance events, which are purely coincidental but blamed on the vaccine, are more likely to occur.  

Definition and types of AEFI

WHO defines an adverse event following immunisation (AEFI) as a medical incident that takes place after an immunisation, causes concern, and believed to be caused by immunisation?  

There are five types of reaction that could lead to AEFI:

.     Vaccine reaction: These are the adverse event caused or precipitated after the administration of the vaccine even if the vaccine is given correctly, could be caused by the inherent properties of the vaccine. It could be the vaccine antigen itself or could be the vaccine constituents such as preservatives, antibiotics, stabilizers, adjuvants etc.

2.     Programme error: These are the adverse event caused by an error in vaccination programme right from manufacturer, handling, cold chain maintenance, vaccination schedule or administration. These can be avoided by proper vaccination schedule, maintaining cold chain, good equipments and providing facilities.

3.     Injection reaction: These are the adverse event caused by the anxiety, or pain from, the injection itself rather than the vaccine, even after safe injection practice. Some individuals may be phobic to the prick of the needle itself and may faint.

4.     Coincidental: These are the adverse event that occurs after vaccination but are not caused by the vaccine. It could be just a chance association with the vaccination which is very difficult for the individuals to understand.

5.     Unknown: These are the adverse event’s whose cause cannot be determined.  

We request you to kindly report for any adverse event / death experienced after getting vaccination even if in the past, as this will help us to improve the efficacy of vaccination programme by reporting the same to government of india, state government and the drug manufacturing companies.

Report AEFI by email at :

Last Updated on Saturday, 27 June 2009 14:07