Effectiveness of mass oral cholera vaccination in Beira, Mozambique.
BACKGROUND
New-generation, orally administered cholera vaccines offer the promise of improved control of cholera in sub-Saharan Africa. However, the high prevalence of human immunodeficiency virus (HIV) infection in many cholera-affected African populations has raised doubts about the level of protection possible with vaccination. We evaluated a mass immunization program with recombinant cholera-toxin B subunit, killed whole-cell (rBS-WC) oral cholera vaccine in Beira, Mozambique, a city where the seroprevalence of HIV is 20 to 30 percent.


METHODS
From December 2003 to January 2004, we undertook mass immunization of nonpregnant persons at least two years of age, using a two-dose regimen of rBS-WC vaccine in Esturro, Beira (population 21,818). We then assessed vaccine protection in a case-control study during an outbreak of El Tor Ogawa cholera in Beira between January and May 2004. To estimate the level of vaccine protection, antecedent rates of vaccination were compared between persons with culture-confirmed cholera severe enough to have prompted them to seek treatment and age- and sex-matched neighborhood controls without treated diarrhea.


RESULTS
We assessed the effectiveness of the vaccine in 43 persons with cholera and 172 controls. Receipt of one or more doses of rBS-WC vaccine was associated with 78 percent protection (95 percent confidence interval, 39 to 92 percent; P=0.004). The vaccine was equally effective in children younger than five years of age and in older persons. A concurrently conducted case-control study designed to detect bias compared persons with treated, noncholeraic diarrhea and controls without diarrhea in the same population and found no protection associated with receipt of the rBS-WC vaccine.


CONCLUSIONS
The rBS-WC vaccine was highly effective against clinically significant cholera in an urban sub-Saharan African population with a high prevalence of HIV infection.
Lucas
Marcelino E S
ME
Ministry of Health, Maputo, Mozambique.
Deen
Jacqueline L
JL
von Seidlein
Lorenz
L
Wang
Xuan-Yi
XY
Ampuero
Julia
J
Puri
Mahesh
M
Ali
Mohammad
M
Ansaruzzaman
M
M
Amos
Juvenaldo
J
Macuamule
Arminda
A
Cavailler
Philippe
P
Guerin
Philippe J
PJ
Mahoudeau
Claude
C
Kahozi-Sangwa
Pierre
P
Chaignat
Claire-Lise
CL
Barreto
Avertino
A
Songane
Francisco F
FF
Clemens
John D
JD
D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D002771:Cholera / Q000453:epidemiology / Q000517:prevention & control*; D002772:Cholera Toxin; D022121:Cholera Vaccines; D003967:Diarrhea / Q000453:epidemiology / Q000821:virology; D005240:Feasibility Studies; D005260:Female; D015658:HIV Infections / Q000150:complications; D006801:Humans; D017589:Immunization Programs; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009073:Mozambique / Q000453:epidemiology; D010446:Peptide Fragments; D011159:Population Surveillance; D016896:Treatment Outcome; D015164:Vaccines, Inactivated; D014734:Vibrio cholerae / Q000302:isolation & purification
D022121:Cholera Vaccines; D010446:Peptide Fragments; D015164:Vaccines, Inactivated; C050310:cholera toxin, B subunit (50-64); D002772:Cholera Toxin