PH9.4 | PH9.4 | Vaccine Pharmacology — SDL Guide — Summary & Reflection

KEY TAKEAWAYS

Vaccines produce active immunity through antigen exposure without disease; passive immunity (immunoglobulin) is immediate but temporary. Vaccine types: live attenuated (BCG, OPV, MMR, varicella, yellow fever — strongest immunity, absolutely contraindicated in immunocompromised patients); inactivated/killed (IPV, hepatitis A, whole-cell pertussis — safe in immunocompromised, require boosters); subunit (hepatitis B rHBsAg, acellular pertussis — safe, need adjuvants); toxoids (tetanus, diphtheria — target inactivated exotoxin; booster every 10 years); conjugate (Hib, PCV, meningococcal — polysaccharide + protein converts T-independent to T-dependent response, enabling infant immunisation); recombinant vector (ChAdOx1 COVID-19; rare VITT adverse event with adenoviral vectors); mRNA (BNT162b2, mRNA-1273 — no live organism, transient mRNA, rare myocarditis in young males). Cold chain: most vaccines +2°C to +8°C; some live vaccines -20°C; freeze-sensitive vaccines destroyed by freezing. Live vaccines: 4 weeks before starting immunosuppression. Hepatitis B vaccine is recombinant subunit — NOT live, cannot cause hepatitis B.

REFLECT

Think about a patient you might encounter who refuses to vaccinate their child because they 'read online that vaccines cause autism.' What do you know now about vaccine pharmacology — the mechanisms, the evidence, the classification — that would help you have an evidence-based conversation with this family? How would you address the specific fear about MMR and autism? Separately, if you were to design a vaccination catch-up schedule for an adult patient about to start infliximab for Crohn's disease, which vaccines would you prioritise, and which would you categorically avoid? Reflect on how this module connects to the immunomodulators module and why that connection matters clinically.