The vaccine now costs $1.50 a dose when purchased for developing countries, and the price will drop to $1 or less if donors order more than 100 million doses, said Bharat’s chairman, Krishna M. Ella. The vaccine has been tested and used in India since 2005.

It gained approval for worldwide use after an unusual “challenge trial” that began in 2015. About 100 healthy volunteers in Oxford, England — many of them students — received the vaccine or a placebo, and then swallowed live Salmonella typhi.

The results, published in the Lancet last year, showed the vaccine to be 87 percent effective in preventing typhoid fever. Those who did fall ill were promptly cured with antibiotics.

Bharat, which makes vaccines against nine other diseases, including one approved by the W.H.O. for polio, is developing immunizations against Ebola, chikungunya, Zika and non-typhoid strains of Salmonella.