Typhoid Vaccine
Typhoid fever (Salmonella Typhi) · Paratyphoid fever
Typhoid fever is a systemic bacterial illness caused by Salmonella Typhi, endemic in South Asia, Southeast Asia, sub-Saharan Africa, and parts of Latin America. Without treatment, case fatality can reach 10–20%. Untreated, typhoid causes sustained high fever, abdominal pain, rose spots, and potentially fatal intestinal perforation or hemorrhage. Drug-resistant typhoid (XDR typhoid) is an emerging global concern.
Overall Benefit Score
Default scenario · 12-month-old · US community (92% vax rate)
Score for your child →Worth careful consideration. Disease risk in your scenario is lower than average, or the vaccine risk/uncertainty is somewhat higher. Discuss timing and priorities with your provider.
📊 Evidence Scores
Scores computed from peer-reviewed data using VaxFact's evidence model. Based on default scenario (12-month-old, standard US community).
🦠 Disease Burden
Typhoid fever is a systemic bacterial illness caused by Salmonella Typhi, endemic in South Asia, Southeast Asia, sub-Saharan Africa, and parts of Latin America. Without treatment, case fatality can reach 10–20%. Untreated, typhoid causes sustained high fever, abdominal pain, rose spots, and potentially fatal intestinal perforation or hemorrhage. Drug-resistant typhoid (XDR typhoid) is an emerging global concern.
Typhoid causes 2–4 weeks of debilitating high fever and gastrointestinal illness. Complications include intestinal perforation (requiring emergency surgery), encephalopathy, and internal bleeding. XDR typhoid from Pakistan is resistant to nearly all oral antibiotics — increasing severity of untreated disease.
🛡️ Vaccine Effectiveness
Injectable Typhim Vi: ~75% effective for 2–3 years; revaccinate every 2 years for ongoing travel. Oral Vivotif: similar efficacy; 4-dose oral series, boosts every 5 years. New Vi-TT conjugate vaccine (Typbar-TCV, approved by WHO) is more immunogenic with longer protection — not yet widely available in the US.
Breakthrough typhoid possible — continued food/water hygiene essential alongside vaccination.
⚠️ Adverse Events & Side Effects
All probabilities are per 100,000 doses administered, sourced from VAERS, Vaccine Safety Datalink, and post-licensure surveillance studies.
Common Side Effects
Rare Serious Events
📅 Vaccine Schedule
Revaccinate with injectable every 2 years if travel continues. Oral vaccine booster every 5 years. Children 2–5 years: injectable form; oral only for age 6+.
⚖️ Benefits vs. Considerations
✓ Benefits
- Prevents a disease that can be fatal and is becoming drug-resistant
- Essential for travel to South Asia, Southeast Asia, sub-Saharan Africa
- Two administration options: injectable and oral (flexibility for different patient preferences)
- Clean safety profile — among the best-tolerated travel vaccines
- Single injectable dose 2 weeks before travel — easy to fit into travel preparation
↕ Considerations
- Does not protect against paratyphoid fever (different strains)
- 75–80% effectiveness — food and water hygiene still essential
- Injectable requires revaccination every 2 years for ongoing travel
- Oral vaccine requires 4 doses on alternating days and refrigeration
- XDR typhoid (nearly untreatable) — vaccine is even more important but effectiveness against emerging resistance strains not yet fully established
🔬 What Some Researchers Question
These are legitimate scientific debates — not fringe claims. They represent areas of ongoing research or policy disagreement among credentialed experts.
- The injectable Vi polysaccharide vaccine provides only T-cell-independent immunity and does not generate immunological memory — meaning it requires revaccination every 2 years and has poor immunogenicity in children under 2, who bear much of the global typhoid burden. The newer conjugate vaccine (Vi-TT) solves these limitations but is not yet widely available in the US.
🌫️ Scientific Uncertainties
Honest acknowledgment of what we don't yet know with confidence.
- Effectiveness against XDR (extensively drug-resistant) typhoid strains now circulating in Pakistan — most studies predate XDR emergence
- When the new Vi-TT conjugate vaccine (Typbar-TCV) will achieve broad US availability and CDC recommendation
🌍 International Policy Comparison
How different countries approach this vaccine — revealing where global consensus is strong vs. where policy diverges.