PE18.5 | Immunization in Special Situations — Summary & Reflection

KEY TAKEAWAYS

Immunization in special situations is guided by five principles: live vaccines carry replication risk in immunocompromised hosts; non-live vaccines are safe in all; defer rather than permanently omit; consider household contacts; document and communicate. In HIV, OPV is replaced by IPV and live vaccines are deferred at CD4 <15% — but non-live vaccines proceed and MR is given at CD4 ≥25%. In SCID and severe PID, all live vaccines are permanently contraindicated. In chemotherapy and organ transplantation, live vaccines are deferred until immune recovery; catch-up with live vaccines should occur ≥4 weeks before elective treatment starts. Preterm infants are vaccinated at chronological age with full doses; BCG is deferred if weight <2 kg at birth, but HepB birth dose is given within 24 hours regardless of gestation or weight in infants of HBsAg-positive mothers. After high-dose IVIG, live vaccines (MR, varicella) are deferred for up to 10–11 months. Asplenic children need PCV, meningococcal conjugate, Hib, and annual influenza vaccines. Adolescents need TT/Td and HPV catch-up; travellers need JE, HepA, TCV, meningococcal, and yellow fever vaccines as applicable.

REFLECT

Return to the hook scenario: the HIV-exposed 10-week-old and her HIV-confirmed 4-year-old sibling with CD4 28%. Using the five-step framework, write out your immunization decision for each child, vaccine by vaccine. What would you tell the mother — why OPV is being replaced by IPV for the infant, and why the older sibling should receive MR despite being HIV-positive? Reflect on how you would navigate a situation where the mother is reluctant to vaccinate the HIV-positive child because she fears 'the vaccine will make him sicker.' What evidence would you use, and how would you communicate it without dismissing her concern? How does the principle of 'defer, not omit' change the conversation with parents who believe their child 'cannot be vaccinated'?