Monitoring adverse events following immunisation in developing countries: experience from human papillomavirus vaccination demonstration projects

Background: Surveillance of adverse events following immunisation (AEFIs) is important for maintaining trust in vaccination. This paper discusses retrospective reports by parents and guardians of girls experiencing AEFIs during human papillomavirus (HPV) vaccine demonstration projects in Uganda and Vietnam. Methods: A secondary analysis of data from a population-based survey measuring HPV vaccine coverage of eligible girls and acceptability among parents and guardians was conducted. Survey data from parents were analysed for frequency and type of AEFI and actions taken. Results: Of the 1700 eligible households contacted, all responded to the survey; of those, 1313 respondents had an eligible child who had received at least one dose of the HPV vaccine. Data were missing from 49 respondents, resulting in 1264 surveys. Twenty-five percent reported an AEFI, with fever (29.1%) and pain or swelling at the injection site (62.0%) being the most common. Events totalled 386 (10.5%) of the 3684 doses administered. Most parents reported that they took no action (63.9%) or cared for girls at home (16.1%) following an AEFI. Thirty-three parents sought advice from health workers or attended a clinic for 46 events (0.8% of all doses). Frequency of reporting varied by respondent identity, geographic location and vaccination location. Conclusions: AEFIs reported were similar to Phase III vaccine trials. Most parents reporting AEFIs took no action or treated the girl at home, suggesting that most AEFIs were not serious enough to contact the health system. AEFI reports were more frequent when solicited in surveys compared with reports from routine monitoring.