NEW DELHI (NYTIMES) - India, the unmatched vaccine manufacturing power, is giving away millions of doses to neighbours friendly and estranged. It is trying to counter China, which has made doling out shots a central plank of its foreign relations. And the United Arab Emirates, drawing on its oil riches, is buying jabs on behalf of its allies.

The coronavirus vaccine - one of the world's most in-demand commodities - has become a new currency for international diplomacy.

Countries with the means or the know-how are using the shots to curry favour or thaw frosty relations. India sent them to Nepal, a country that has fallen increasingly under China's influence. Sri Lanka, in the midst of a diplomatic tug of war between New Delhi and Beijing, is getting doses from both.

The strategy carries risks. India and China, both of which are making vaccines for the rest of the world, have vast populations of their own that they need to inoculate. Though there are few signs of grumbling in either country, that could change as the public watches doses get sold or donated abroad.

"Indians are dying. Indians are still getting the disease," said Mr Manoj Joshi, a distinguished fellow at the Observer Research Foundation, a New Delhi think tank. "I could understand if our needs had been fulfilled and then you had given away the stuff. But I think there is a false moral superiority that you are trying to put across where you say we are giving away our stuff even before we use it ourselves."

The donating countries are making their offerings at a time when the United States and other rich nations are scooping up the world's supplies. Poorer countries are frantically trying to get their own, a disparity that the World Health Organisation recently warned has put the world "on the brink of a catastrophic moral failure."

With their health systems tested like never before, many countries are eager to take what they are offered - and the donors could reap some political good will in reward.

"Instead of securing a country by sending troops, you can secure the country by saving lives, by saving their economy, by helping with their vaccination," said Ms Dania Thafer, the executive director of the Gulf International Forum, a Washington-based think tank.

China was one of the first countries to make a diplomatic vaccine push, promising to help developing countries last year even before the nation had mass produced a vaccine that was proved to be effective. Just this week, it said it would donate 300,000 vaccine doses to Egypt.

But some of China's vaccine-diplomacy efforts have stumbled from supplies arriving late, a lack of disclosure about the efficacy of its vaccines and other issues. Chinese government officials have cited unexpectedly strong needs at home amid isolated outbreaks, a move that could blunt any domestic backlash.

Even as Chinese-made vaccines spread, India saw a chance to bolster its own image.

The Serum Institute of India, the world's largest vaccine factory, churns out the AstraZeneca-Oxford vaccine at a daily rate of about 2.5 million doses. That pace has allowed India to begin to dole out doses free of charge to neighbours. To much fanfare, planeloads have arrived in Nepal, Bangladesh, Myanmar, the Maldives, Sri Lanka, the Seychelles and Afghanistan.

"Acting East. Acting fast," said Mr S. Jaishankar, India's foreign minister, announcing the arrival of 1.5 million doses in Myanmar, on Twitter.

The Indian government has tried to score publicity points for doses shipped to places like Brazil and Morocco, though those countries purchased theirs. The Serum Institute has also pledged 200 million doses to a global WHO pool called Covax that would go to poorer nations, while China recently pledged 10 million.

For now, the Indian government has room to donate abroad, even after months when cases soared and the economy was hobbled, and even as it has vaccinated just a tiny per cent of its 1.3 billion people. Part of the reason for a lack of backlash: the Serum Institute is producing at a faster rate than India's inoculation programme can currently handle, leaving extras for donations and exports.

And some Indians are not in a rush to get vaccinated because of skepticism over a homegrown vaccine called Covaxin. The Indian government approved its emergency use without disclosing much data about it, leading some people to doubt its effectiveness. While the AstraZeneca-Oxford jab has faced less skepticism, those getting vaccinated don't have a choice of which vaccine they receive.

For India, its soft-power vaccine drive has given it a rejoinder to China, after years of watching the Chinese make political gains in its own backyard - in Sri Lanka, the Maldives, Nepal and elsewhere. Beijing offered deep pockets and swift answers when it came to big investments that India, with a layered bureaucracy and slowing economy, has struggled to match.

"India's neighbourhood has become more crowded, more competitive," said Mr Constantino Xavier, who studies India's relations with its neighbours at the Centre for Social and Economic Progress, a New Delhi think tank. "The vaccine push bolsters India's credibility as a reliable crisis-responder and solutions provider to these neighbouring countries."

Still, the strategy of using vaccines to win hearts and minds isn't always successful.

The United Arab Emirates, which is rolling out vaccines faster than any country except Israel, has begun donating Chinese-made Sinopharm vaccines it purchased to countries where it has strategic or commercial interests, including 50,000 doses each to the Seychelles, the island nation in the Indian Ocean, and Egypt, one of its Arab allies.

But in Egypt some doctors balked at using them, because they said they did not trust the data the UAE and the vaccine's Chinese maker had released about trials.

The government of Malaysia, one of the Emirates' biggest trading partners, declined an offer of 500,000 doses, saying that regulators would have to independently approve the Sinopharm vaccine. After regulatory approval, Malaysia bought vaccines instead from Pfizer, the AstraZeneca-Oxford vaccine and one made by another Chinese company, Sinovac.