Among children receiving vaccines under the Universal Immunisation Programme in India, what is the most common site of adverse events following immunisation (AEFI) with injectable vaccines?

Explanation

## Local Reactions as the Most Common AEFI in UIP **Key Point:** Local reactions at the injection site (pain, swelling, erythema, induration) are the most frequent adverse events following immunisation with injectable vaccines in India's UIP. ### Frequency and Clinical Significance of AEFI Types | AEFI Category | Frequency | Severity | Clinical Significance | |---------------|-----------|----------|----------------------| | Local reactions | 10–50% | Mild | Expected, self-limiting | | Systemic reactions (fever, malaise) | 5–15% | Mild to moderate | Usually resolves in 24–48 hrs | | Neurological events | <0.1% | Severe | Rare; often coincidental | | Anaphylaxis | <1 per million | Life-threatening | Medical emergency | ### Local Reactions: Expected and Managed **High-Yield:** Local reactions are: - Expected after DPT, tetanus toxoid, and inactivated polio vaccine (IPV) - Usually appear within 24–48 hours - Self-limiting and resolve without intervention - Do NOT contraindicate further doses ### Why Other Options Are Less Common **Systemic reactions (fever, malaise):** - Occur in 5–15% of vaccinees - More common with live vaccines (OPV, MMR) - Less frequent than local reactions overall **Neurological complications:** - Extremely rare (<0.1% of vaccinations) - Often coincidental temporal associations - Extensive post-licensure surveillance shows no causal link for most vaccines **Anaphylaxis:** - Rarest AEFI (<1 per million doses) - Occurs in seconds to minutes - Requires emergency management ### Clinical Pearl The UIP's AEFI surveillance system distinguishes between: - **Expected AEFI** (e.g., local reactions): Reassurance and supportive care - **Unexpected AEFI** (e.g., severe neurological events): Investigation and reporting to pharmacovigilance **Mnemonic:** **LSNA** = Local reactions (most common) → Systemic reactions → Neurological → Anaphylaxis (rarest) **Warning:** Parents often confuse expected local reactions with true adverse events. Clear counselling before vaccination reduces anxiety and improves vaccine acceptance. [cite:Park 26e Ch 9]