India is accelerating its review of coronavirus vaccines developed by Pfizer Inc and AstraZeneca for emergency use, a senior government official said on Monday, as the world's second-most affected country struggles to contain the outbreak.

The Indian government is pinning its hopes for mass supply of the vaccine on Serum Institute of India, the world's largest vaccine producer by volume, which on Monday lodged the first formal application for emergency use approval for AstraZeneca Plc's Covid-19 vaccine.

Pfizer Inc had already applied for emergency use approval for its vaccine in India over the weekend, the official said, declining to be identified.

“We are in the process of reviewing. It is an accelerated reviewing process, which is there for Serum too,” the government official said.

“It is the need of the hour. We have to review at the earliest.”

The world's second-most populous country with over 1.3 billion people has 9.68 million infections, while more than 140,000 people have died of Covid-19. Lockdowns imposed to contain the spread of the virus have plunged the economy into one of its worst downturns in decades.

Serum Institute CEO Adar Poonawalla tweeted that the move to apply for emergency use “will save countless lives,” but did not give any other details.

The company declined to reply to Reuters' follow-up questions about the process.

AstraZeneca, Pfizer and Moderna Inc are among the drugmakers seeking advanced approvals for their vaccines, which are increasingly being seen by governments as the only way to stop a pandemic that will soon complete a year since it was first reported in China.

AstraZeneca's vaccine, called “Covishield” by Serum Institute, has less stringent storage requirements and is expected to be easier to distribute and faster to scale up in low-income countries.

But it is also facing queries from scientists over its trial data, which showed a 1.5 dose regimen delivered more than 90% efficacy and a full two-dose regimen just 62%, both administered over two stages.

Britain and some other nations have pressed on with plans to roll out the AstraZeneca vaccine, while the Philippines and Thailand secured millions of doses, giving the shot a vote of confidence after experts raised questions about trial data.

AstraZeneca said two weeks ago that it could launch an additional trial to evaluate the lower dose regimen, but Serum Institute has said it would continue to test only the two full doses as it would delay trials.

Poonawalla has said the company will first focus on supplying the vaccine in India before distributing it to other countries, pricing it at 1,000 rupees per dose ($13.50) for private markets.

Serum Institute has also said an emergency use approval could preface a full rollout by February or March.