Protective efficacy of oral whole-cell/recombinant-B-subunit cholera vaccine in Peruvian military recruits
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Published on: August 30, 2014
J L Sanchez1, B Vasquez, R E Begue
1Division of Preventive Medicine, Walter Reed Army Institute of Research, Washington, DC.
Insights
This study shows the oral inactivated whole-cell/recombinant-B-subunit (WC/rBS) cholera vaccine provided significant short-term protection against symptomatic cholera in Peruvian adults. The WC/rBS vaccine demonstrated 86% efficacy against cholera cases.
Area of Science:
- * Infectious Diseases
- * Vaccinology
- * Public Health
Background:
- * The South American cholera epidemic highlighted the urgent need for effective oral vaccines.
- * Oral inactivated whole-cell/recombinant-B-subunit (WC/rBS) cholera vaccine efficacy was investigated.
- * Previous research indicated a need for rapid, short-term protection strategies.
Purpose of the Study:
- * To evaluate the protective efficacy of an oral WC/rBS cholera vaccine.
- * To assess vaccine effectiveness against symptomatic cholera and asymptomatic infections.
- * To analyze the impact of blood group O on vaccine efficacy.
Main Methods:
- * A randomized, double-blind, placebo-controlled efficacy trial.
- * 1563 Peruvian military recruits received two oral doses of WC/rBS vaccine or placebo (E. coli K12).
- * Participants were followed for a mean of 18 weeks post-vaccination.
Main Results:
- * The WC/rBS vaccine showed significant protective efficacy against symptomatic cholera (86%, p < 0.01).
- * No significant protection was observed against asymptomatic infections (42%).
- * All cholera cases occurred in individuals with blood group O, comprising 76% of the study population.
Conclusions:
- * Two doses of WC/rBS vaccine offer rapid, short-term protection against symptomatic cholera in adults.
- * The vaccine's efficacy is significant for symptomatic cholera but not asymptomatic infections.
- * Further long-term efficacy studies in diverse populations are warranted.
Abstract:
The cholera epidemic in South America has reinforced the need for safe and effective oral vaccines. In a randomised, double-blind, placebo-controlled efficacy trial among 1563 Peruvian military recruits we have investigated the protective efficacy of an oral inactivated whole-cell/recombinant-B-subunit (WC/rBS) cholera vaccine. Participants were given two oral doses of cholera vaccine or Escherichia coli K12 placebo, with an interval of 7-14 days. 1426 (91%) subjects received the two prescribed doses and were followed up for a mean of 18 weeks (median 21 weeks). After vaccination, Vibrio cholerae O1 El Tor Ogawa was isolated from 17 subjects with diarrhoea. 16 of the cholera cases occurred 2 weeks or longer after the second dose of vaccine (14 placebo recipients, 2 vaccinees). We also detected 14 symptomless infections (11 [7 placebo recipients, 4 vaccinees]) 2 weeks or longer after the second dose. The vaccine had significant protective efficacy against cholera (86% [95% CI 37-97], p < 0.01) but not against symptomless infection (42% [-96 to 85]). All cholera cases were in people of blood group O, who made up 76% of the study population (p < 0.01). Two doses of WC/rBS vaccine, given 1 to 2 weeks apart, provide rapid, short-term protection against symptomatic cholera in adult South Americans, who are predominantly of blood group O. Long-term efficacy studies in Peruvian adults and children are under way.
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