Benenson 1968a.

Methods	Quasi‐randomized controlled trial Generation of allocation sequence: sequential allocation Blinding: double blind Completeness: 100% with adverse effect data Surveillance: by daily clinical assessments at home
Participants	Number: 2801 residents (all ages, both sexes) 87 staff of a military hospital (who had previously been vaccinated many times) and 419 residents of Kadamtali village, Matlab
Interventions	Injected cholera vaccines: CRL: Classical bivalent phenol‐killed whole cell 13: Classical bivalent phenol killed whole cell T: lipopolysaccharide (El Tor Ogawa) Placebos: TAB Tetanus toxoid Saline Route: injected Dose: 1 or 2 doses
Outcomes	Geometric mean agglutinin titre and vibriocidal titre to Ogawa antigen Adverse effects in 24 hours
Location	East Pakistan: Bandar refugee colony, Mudafa (a rural area), and Kaliganj (a semi‐urban area)
Notes	Only the military hospital and Kadamtali village have adverse effect data. Data from the military hospital is excluded as it is not possible to match the 164 vaccinations to the 87 subjects (each participant vaccinated twice, often with different vaccines). Data for Kadamtali (for vaccines 1 and 3 combined) have been estimated from a Figure. The placebo was tetanus toxoid