Study	Reason for exclusion
Beran 1964	Observational study
Beran 1965	Nonrandomized study
Black 1979	Nonrandomized study
Cabrera 2005	Not a trial – preparation of vaccine.
Chandra Sekar 1947	Observational study (note 'block' unit of observation)
Clasener 1968	Immunological outcomes only
Ganguly 1975	Immunological outcomes only
Gateff 1975	Immunological outcomes only
Gupta 1998	No placebo group; immunological and adverse outcomes only. Phase 1 trial comparing 2 polysaccharide cholera toxin conjugate vaccines and polysaccharide alone with licensed killed whole cell vaccine. None of the tested vaccines progressed to efficacy trials
McBean 1972	Immunological outcomes only
Mosley 1968	Seroprevalence study
Nimbkar 1975	Immunological outcomes only
Peltola 1977	Nonrandomized study
Russell 1927	Nonrandomized study
Sommer 1973a	Randomized controlled trial, but vaccine given after exposure to cholera in family members