Investigation of adverse events following immunization with liquid pentavalent vaccine in Sri Lanka
Background
Quinvaxem® was prequalified by WHO in September 2006 and is supplied through UN agencies to several countries for routine immunization in the public health sector. More than 34 million doses of the vaccine had been distributed worldwide as at March 2008. The vaccine has also been available through the private sector in a limited number of countries.
In Sri Lanka, during the period from 1 January 2008 to 29 April 2008, five reports of fatal AEFIs and 20 reports of non-fatal AEFIs described as suggestive of hypotonic-hyporesponsive episode (referred to as HHE-like) following use of the pentavalent vaccine had been submitted to the Epidemiological Unit of the Ministry of Health. HHE is a recognized adverse reaction to whole-cell and acellular pertussis-containing vaccines, and to Haemophilus influenzae type b and hepatitis B vaccines. It is self-limited with no long-term sequelae. It is of note that concurrent with the introduction of this new vaccine in its national immunization programme, Sri Lanka enhanced monitoring of adverse events.