Vaccine strategy

What are the two main types of vaccines, and which one generally provides better protection?

Viable (Live) and Non-Viable (Inactivated). Viable vaccines generally provide better and longer-lasting protection.

Why are capsular polysaccharides in the Hib and PCV vaccines conjugated to a protein?

Pure polysaccharides are relatively non-immunogenic (poorly stimulate an immune response) in young children. Conjugation to a protein makes them more effective and generates a stronger, T-cell dependent immune response.

What is the key strategic difference between the use of PCV and PPV vaccines for Pneumococcus?

PCV (conjugate) is used in the childhood schedule as it is effective in under-2s. PPV (plain polysaccharide) is not suitable for under-2s and is used for adults ≥65 and high-risk groups, representing a targeted, age-appropriate strategy.

Name three key complications associated with each of the MMR diseases.

• Measles: Encephalitis, SSPE, Pneumonia.

• Mumps: Orchitis, Sensorineural Deafness, Meningitis.

• Rubella: Congenital Rubella Syndrome (CRS) in foetuses (cataracts, deafness, cardiac defects).

What is herd immunity and how does vaccine compliance relate to it?

Herd immunity occurs when a high percentage of the population is vaccinated, providing indirect protection to unvaccinated individuals. If compliance falls, herd immunity is lost, allowing diseases to spread in the population.