Protective efficacy of oral whole-cell/recombinant-B-subunit cholera vaccine in Peruvian military recruits.
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.
Division of Preventive Medicine, Walter Reed Army Institute of Research, Washington, DC.
J L
JL
Sanchez
B
B
Vasquez
R E
RE
Begue
R
R
Meza
G
G
Castellares
C
C
Cabezas
D M
DM
Watts
A M
AM
Svennerholm
J C
JC
Sadoff
D N
DN
Taylor
D000017:ABO Blood-Group System; D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D002771:Cholera / Q000097:blood / Q000453:epidemiology / Q000382:microbiology / Q000517:prevention & control*; D022121:Cholera Vaccines; D004311:Double-Blind Method; D005500:Follow-Up Studies; D006801:Humans; D007115:Immunization Schedule; D015994:Incidence; D008297:Male; D008875:Middle Aged; D008889:Military Personnel; D010568:Peru / Q000453:epidemiology; D012703:Serotyping; D015164:Vaccines, Inactivated; D014614:Vaccines, Synthetic; D014734:Vibrio cholerae / Q000145:classification
D000017:ABO Blood-Group System; D022121:Cholera Vaccines; D015164:Vaccines, Inactivated; D014614:Vaccines, Synthetic