Examples of AEFI clusters

Example 1

An outbreak of lymphadenitis 3 months after BCG immunization was traced to a switch to a different strain of vaccine. The investigation also highlighted a number of immunization errors (vaccines not properly reconstituted, and injections not given intradermally).

Cause: vaccine reaction compounded by immunization errors.

Illustration 2

Four children died and a fifth was hospitalized after receiving measles vaccine from the same vial. The vaccine was not refrigerated, and was transported from house to house for immunization. Reactions began 4-5 hours after vaccination, with vomiting, unconsciousness, and meningeal irritation. Staphylococcus aureus bacteria were cultivated from the incriminated vial.

Cause: sepsis caused by inappropriate vaccine handling.