Knowledge, perception and reporting attitudes of adverse events following immunization among parents of infants in rural area, Sri Lanka: a community-based cross-sectional study

Background Adverse events following immunization (AEFI) play a critical role in shaping parental confidence and the effectiveness of vaccine safety surveillance systems. Despite the predominantly mild and self-limiting nature of most AEFIs, inadequate awareness and misperceptions may contribute to underreporting and undermine trust in immunization programmes. Evidence on parental knowledge, perception, and reporting practices regarding AEFI in Sri Lanka remains scarce, particularly in rural settings. Methods A community-based cross-sectional study was conducted among parents of infants in the Buttala Medical Officer of Health area, Sri Lanka. A total of 393 participants were selected using systematic random sampling from Public Health Midwife registers. Data were collected using a pre-tested interviewer-administered questionnaire assessing socio-demographic characteristics, knowledge, perception, and reporting attitudes related to AEFI. Knowledge was evaluated using a ten-item scoring system, with scores >6 indicating adequate knowledge. Associations were assessed using chi-square tests, and effect sizes were expressed as odds ratios (OR) with 95% confidence intervals (CI). Results Overall, 73% (n = 287) of participants demonstrated adequate knowledge of AEFI. While awareness of common adverse events was high, knowledge of serious AEFIs remained limited, with only 48.1% (n = 189) identifying severe reactions such as anaphylaxis and convulsions. Adequate knowledge was significantly associated with age ≥30 years (OR = 2.99; 95% CI: 1.90–4.77), higher educational attainment (OR = 2.52; 95% CI: 1.56–4.06), higher household income (OR = 2.12; 95% CI: 1.04–4.35), and infant age ≥6 months (OR = 1.82; 95% CI: 1.16–2.85). Although overall perception towards immunization was highly positive, with 94.9% expressing confidence in the national programme, reporting practices were suboptimal. Among parents who experienced an AEFI, only 56.9% reported the event, while a substantial proportion (43.1%) did not report, often perceiving minor events as insignificant. Conclusion Despite generally favourable levels of knowledge and positive perceptions, critical gaps persist in the recognition of serious AEFIs and in reporting behaviour. The observed disconnect between awareness and reporting highlights the need for targeted risk communication strategies and strengthened community-based reporting systems. Addressing these gaps is essential to improve AEFI surveillance and sustain long-term public confidence in immunization programmes.