What is the efficacy of Dukoral (Cholera vaccine) for preventing cholera and E. coli (Escherichia coli) infections?

Dukoral Efficacy for Cholera and E. coli

Dukoral demonstrates approximately 85% efficacy against cholera at 6 months post-immunization, but provides only modest and inconsistent protection against E. coli-related traveler's diarrhea, with effectiveness ranging from 0-43% depending on the population studied. 1

Efficacy Against Cholera

For cholera prevention, Dukoral provides robust short-term protection:

• Efficacy reaches ~85% at 6 months after completing the two-dose series (administered 1-6 weeks apart) 1
• Duration of protection varies considerably between individuals, lasting up to 3 years in some cases 1
• The vaccine contains killed whole-cell Vibrio cholerae O1 (both Inaba and Ogawa serotypes, Classical and El Tor biotypes) plus purified recombinant B subunit of cholera toxin 1, 2
• It is the only internationally available cholera vaccine, licensed in approximately 20 countries 1

Efficacy Against E. coli (ETEC)

The evidence for protection against enterotoxigenic E. coli (ETEC) is substantially weaker and more variable:

Traveler Populations:

• A Cochrane systematic review found no statistically significant protection against ETEC diarrhea or all-cause diarrhea in travelers (one trial, 502 participants, low quality evidence) 3
• Individual observational studies show conflicting results:
  • One Spanish cohort study demonstrated 28% adjusted effectiveness (95% CI: 12-42%) with a number needed to vaccinate of 10 4
  • A retrospective Spanish study showed 43% risk reduction in traveler's diarrhea 5
  • Protection appears modified by age (under 30 or over 45 years showed 4.8 times greater protective effect) 5

Mechanism of Cross-Protection:

• The recombinant cholera toxin B subunit cross-reacts with E. coli heat-labile toxin (LT), theoretically providing protection against LT-producing ETEC strains 1, 2, 6
• One expert review suggests protective efficacy against heat-labile ETEC toxin reaches 67%, though this is not consistently replicated 6

Duration Against ETEC:

• Protection against ETEC, when present, is short-term, lasting approximately 3 months 3
• This is substantially shorter than cholera protection 3

Important Clinical Caveats

Key limitations to consider when counseling patients:

• The vaccine is NOT licensed in the United States for cholera prevention and most Western countries only license it for cholera, not ETEC 1
• A precursor vaccine containing purified (not recombinant) cholera toxin B subunit showed better ETEC protection (RR 0.43,95% CI 0.26-0.71) but is no longer available 3
• ETEC-specific vaccines containing the recombinant B-subunit have not demonstrated clinically important benefits and were associated with increased vomiting (RR 2.0,95% CI 1.16-3.45) 3
• The Cochrane review concludes there is currently insufficient evidence to support using Dukoral for protecting travelers against ETEC diarrhea 3

Practical Recommendations

For cholera-endemic areas:

• Dukoral provides reliable protection and should be considered for travelers to areas with active cholera transmission 1
• Primary prevention through safe water, food precautions, and sanitation remains the cornerstone of cholera control 1

For ETEC/traveler's diarrhea:

• Do not rely on Dukoral as primary prevention strategy given inconsistent evidence 3
• May provide modest benefit in specific high-risk scenarios (young adults or those over 45 traveling to Africa or South Asia for extended periods) 5
• Consider for at-risk travelers with high exposure or those who would tolerate fluid loss poorly, but counsel on limited evidence 6