The oral cholera vaccine 3 pills generally refers to the oral recombinant B subunit/mycobacterial cholera vaccine, which has been shown to have a rapidly declining protective effect in young children after 6 months of vaccination, and a protective effect that lasts for 2 to 3 years in older vaccinees. Oral recombinant B subunit/mycobacterial cholera vaccine is made from recombinant cholera toxin B subunit prepared from engineered bacteria and freeze-dried with inactivated Vibrio cholerae mycobacteria, and the first-time immunized person is required to take three doses of one capsule orally on days 0, 7, and 28, respectively. Studies have shown that the oral vaccine, given before a cholera outbreak, provides protection of up to 78% after one or more doses of the vaccine. The protective effect of the vaccine declines rapidly in young children after 6 months of vaccination, but protection lasts for 2 to 3 years in older vaccinees. Although the vaccine lasts longer, a booster is needed before the epidemic season for those who have been immunized with the vaccine. Please follow your doctor’s instructions for specific vaccinations.