NEW DELHI: India expects to receive 3 million to 4 million doses of the Pfizer and Moderna COVID-19 shots through the COVAX facility by August, two sources said, as it tries to expand inoculations to prevent another surge in infections.

COVAX, led by the GAVI vaccine alliance and the World Health Organization (WHO), could ship the U.S.-made doses to India as early as this month, one of the sources aware of the discussions told Reuters.

"It's a donation through COVAX," said the source. Both sources declined to be named as the discussions are private.

Pfizer and Moderna did not immediately reply to Reuters' e-mails seeking comment. GAVI and India's foreign ministry also did not reply to queries.

India is the world's biggest producer of vaccines overall. It donated or sold more than 66 million doses of COVID-19 shots before a huge rise in infections forced it to divert all domestic output to inoculate its own people from April.

The country has so far administered 358.1 million vaccine doses - the most in the world after China - giving at least one dose to 31% of its estimated adult population of 944 million.

India mainly relies on a licensed version of the AstraZeneca vaccine.

Experts have said India needs to administer 10 million doses a day to achieve its aim of immunising all adults by December. It administered about 4 million doses a day in the week to July 2.

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Apart from Moderna and Pfizer, India has also been courting Johnson & Johnson for vaccine supplies. J&J has already signed a manufacturing agreement with India's Biological E. Ltd though production has yet to start.

A J&J spokesperson in India said the company was looking to expedite vaccine supplies to the country.

"We are exploring how best to accelerate our ability to deliver our vaccine to the people of India through our global COVID-19 vaccine supply network, including our partnership with Biological E. Limited," the spokesperson told Reuters in an e-mail.