Typhoid Vi: a less reactogenic vaccine

Area of Science:

• Immunology
• Vaccinology
• Infectious Diseases

Background:

• Typhoid fever remains a significant global health concern, necessitating effective vaccination strategies.
• Traditional heat-killed whole-cell typhoid vaccines are associated with notable local and systemic adverse reactions.
• The development of safer and more targeted typhoid vaccines is crucial for public health.

Purpose of the Study:

• To compare the safety and tolerability of a typhoid vaccine derived from purified Vi capsular polysaccharide (CPS) antigen against a heat-killed whole-cell typhoid vaccine.
• To evaluate local and systemic adverse reactions following immunization with Vi CPS and whole-cell typhoid vaccines.

Main Methods:

• A randomized controlled trial involving 637 healthy male volunteers.
• Three groups were established: one receiving two doses of whole-cell vaccine, and two receiving a single dose of Vi CPS vaccine with a placebo.
• Adverse reactions were systematically recorded for 5 days post-injection.

Main Results:

• The typhoid Vi CPS vaccine group reported significantly fewer local adverse reactions compared to the whole-cell vaccine group (18.6% vs. 59.7% on day 1, P < 0.001).
• Systemic reactions were also less frequent in the Vi CPS vaccine recipients (3.4% vs. 7.9% on day 1, P < 0.01).

Conclusions:

• The typhoid Vi CPS vaccine demonstrates a superior safety profile with reduced local and systemic adverse reactions compared to the heat-killed whole-cell vaccine.
• The Vi CPS vaccine represents a potentially safer alternative for typhoid fever prevention.