Surveillance of adverse events following immunization in Oman, 2006-2015

Background: In 1996, Oman launched its surveillance programme for adverse events following immunization (AEFI) to address vaccine safety concerns. In 2010, an analysis of surveillance activities for AEFI was done for 10 years (1996-2005). Objectives: The main objective of the study was to describe the trend of AEFI over the 10-year period, 2006-2015, and compare the findings with a previous report in Oman and reports from other countries. Methods: A descriptive record-based review of AEFI was carried out using the national AEFI surveillance database for the study period, 2006-2015. Results: A total of 890 adverse event reports were received, giving an annual rate during the review period of 21.4 per 100 000 population or 8.3 per 100 000 doses administered. The most frequently reported AEFI were BCG adenitis and local reactions - 31.1 and 4.1 per 100 000 doses respectively. There were no reported deaths. Pentavalent vaccine was responsible for the greatest proportion of adverse events (30%). Local reaction was the most common adverse event among all vaccines administered. The Hexa vaccine caused fewer adverse events compared with the pentavalent vaccine, probably due to the acellular pertussis component – 0.8 versus 1.5 per 100 000 doses administered respectively. Conclusion: The overall rate of AEFI (8.3 per 100 000 doses administered) is comparable to the rate (10.8/100 000 doses) in the previous decade (1996-2005) in Oman. The reported rates for individual vaccines are similar to or below international rates.