Table 2. Advantages and disadvantages of past, present and future vaccines against Salmonella enterica.
Vaccine | Advantages | Disadvantages |
---|---|---|
A Vaccines of the Past | ||
Whole Cell Inactivated | 73% 3-y efficacy | Reactogenicity |
B Established Vaccines | ||
1. Vi CPS | Single dose | Not licensed for infants |
Low reactogenicity | Lack of memory response | |
WHO prequalification | Lack of affinity maturation | |
Only protects against S. Typhi | ||
2. Ty21a | Oral administration | Not licensed for infants |
Some cross-protection against | Requires multiple doses | |
S. Paratyphi B | ||
C New and Future Vaccines | ||
1. Vi glycoconjugate | Higher efficacy than current vaccines | Only protects against S. Typhi |
T-dependent antibody response | ||
Memory induction | ||
Affinity maturation | ||
Low reactogenicity | ||
2. O-antigen glycoconjugate | As for Vi glycoconjugates | Only protects against serovars with same O-antigen specificity |
3. New Live Attenuated | Salmonella-specific B and T cell immunity | Attenuating for optimal balance of immunity and reactogenicity |
Clearance of residual infection | Breadth of coverage may be limited by insufficient expression of key antigens | |
Possibility of disease in immunocompromised subjects | ||
4. Recombinant Proteins | Salmonella-specific B and T cell immunity | Issues with antigen conformation may limit ability to induce effective B cell response |
Potential for pan-specific immunity | ||
Low reactogenicity | ||
5. Proteins purified from whole Salmonellae | Salmonella-specific B and T cell immunity | Difficulties with purification of integral membrane proteins |
Potential for pan-specific immunity | ||
Low reactogenicity | ||
6. GMMA | Salmonella-specific B and T cell immunity | Balance of reactogenicity and immunogenicity in man not currently known |
Potential for pan-specific immunity | ||
Enrichment of membrane antigens | ||
Ease of manufacture Low cost-of-goods |
Adapted with permission from reference 47.