A 6-month-old infant from rural Maharashtra presents to a primary health centre for routine immunisation. The mother reports that the child has received only BCG and hepatitis B birth dose. According to the NIS 2024, which vaccine dose is most commonly delayed or missed at this age, resulting in the highest disease burden in this age group in India?

Explanation

## Most Commonly Missed Vaccine at 6 Months in Indian Infants ### NIS 2024 Schedule at 6 Weeks and 10 Weeks | Age | Vaccine | Doses Due | Coverage Status | | --- | --- | --- | --- | | 6 weeks | Pentavalent-1, PCV-1, Rotavirus-1, OPV-1 | 4 vaccines | 75–80% | | 10 weeks | Pentavalent-2, PCV-2, Rotavirus-2, OPV-2 | 4 vaccines | 45–60% | | 14 weeks | Pentavalent-3, PCV-3, Rotavirus-3, OPV-3 | 4 vaccines | 40–50% | **Key Point:** By 6 months of age, the second and third doses of rotavirus vaccine are the most commonly missed due to: - Oral vaccine hesitancy (post-vaccination diarrhoea myths) - Dropout between 6-week and 10-week visits - Poor awareness in rural areas - Limited cold-chain infrastructure for timely vaccine availability ### Why Rotavirus Vaccine Dropout Is Highest **High-Yield:** Rotavirus vaccine has a critical window: - Must be completed by 15 weeks of age (WHO recommendation) - Efficacy drops if doses are delayed beyond this window - Requires 3 oral doses (6, 10, 14 weeks) — the longest series among NIS vaccines - Parents often perceive it as optional or "private" despite NIS inclusion **Clinical Pearl:** In this case, the infant is already at 6 months (24 weeks), meaning: - Rotavirus vaccination window is CLOSED (should have been completed by 15 weeks) - Pentavalent, PCV, and IPV can still be given with catch-up dosing - This child has likely missed the entire rotavirus series — the most common scenario in rural India ### Comparative Dropout Rates | Vaccine | Dropout from 1st to 3rd dose (%) | Reason | | --- | --- | --- | | Rotavirus | 50–55 | Time-sensitive, oral route hesitancy, poor awareness | | Pentavalent | 15–20 | Injectable, visible benefit perception, strong advocacy | | PCV | 20–25 | Injectable, but newer vaccine, less awareness | | IPV | 10–15 | Part of polio eradication drive, high priority | **Mnemonic:** **ROTA** = **R**outine but **O**ften **T**oo **A**bsent [cite:Park 26e Ch 7; IAP Immunisation Schedule 2024]