Serum has already supplied the Indian government with millions of doses of the AstraZeneca vaccine.
India's Serum Institute, the world's largest vaccine manufacturer, despatched on Tuesday its first batch of vaccine shots for the Covax global inoculation programme.
The global vaccine procurement and equitable distribution effort aims to secure vaccines for at least the most vulnerable 20 percent in every country.
Covax, led by the World Health Organization and the GAVI alliance, has struck agreements with manufacturers for two billion doses in 2021 and has the option for another billion.
This includes 1.1 billion doses from the Serum Institute, which is producing the AstraZeneca and Novavax vaccines.
WHO Southeast Asia tweeted photos of the first shipments being loaded onto a truck at Serum's manufacturing facility in Pune in western India.
Serum has already supplied the Indian government with millions of doses of the AstraZeneca vaccine as well as other poorer nations.
The company's head Adar Poonawalla on Sunday urged other countries to be "patient", saying it had been instructed to prioritise its home market over exports.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)