Dhaka, July 28 -- The Himalayan kingdom of Bhutan has fully vaccinated 90 per cent of its eligible adult population within just seven days, its health ministry said Tuesday.

The tiny country, wedged between India and China and home to nearly 800,000 people, began giving out second doses on July 20 in a mass drive that has been hailed by UNICEF as "arguably the fastest vaccination campaign to be executed during a pandemic."

In April, Bhutan grabbed headlines when its government said it had inoculated around the same percentage of eligible adults with the first dose in under two weeks after India donated 550,000 shots of AstraZeneca vaccine.

But the country faced a shortage for months after India, a major supplier of the AstraZeneca shot...