Nearly 90% of the 1.3 billion total doses administered in India have been the Covishield vaccine, a licensed version of the AstraZeneca shot produced by SII.
The government wants a total of 1.7 billion vaccine doses to fully immunise most of its adults, and the SII plans to make the last of its pending orders to meet its share of that demand by next week.
The SII has said it plans to halve its monthly output of Covishield, which has been 250 million doses, due to a lack of demand.
It is one of seven Indian companies that Russian sovereign wealth fund RDIF has struck deals with to make a total of nearly 1 billion Sputnik doses, both for export and for use in India.
But only 1.2 million doses of Sputnik V have been administered in India, government data shows. Some 4 million doses, bottled in India using imported material from Russia, exported, said two sources.
"We are talking to the regulator to allow it as a booster dose," G.V. Prasad, managing director of Dr Reddy’s, told Reuters in a recent interview about the single-dose Sputnik Light.
"Right now, there's no demand, the market is fully supplied by the Serum Institute. Internationally also, supply is not a constraint anymore."
An Indian pharmaceutical company that was supposed to produce more than 100 million Sputnik doses has put the plan on hold without making a single commercial dose, said a source with direct knowledge of the decision.
The source, who declined to be identified in the interests of maintaining business relations, said the company had moved on to non-COVID products but would switch back to Sputnik if demand returned.
RDIF declined to make any immediate comment.
It said in a statement on Monday that it was "actively cooperating" with Indian authorities to get Sputnik Light approved as a standalone vaccine and booster.
The other vaccines either in trial or waiting approval in India are: Bio E's protein sub-unit vaccine, Bharat Biotech's nasal vaccine and Gennova's mRNA vaccine.
The Indian government said in May it expected 460 million doses of the three shots between August and December, but no commercial production has begun.
Gennova says it expects demand to come from boosters, overseas markets and children when its shot hits the market after trials.
Bio E, Bharat Biotech, Cadila and India's health ministry did not respond to requests for comment.
Vaccination for those under the age of 18 in India has not started yet, a market most of the companies are targeting next.
(Reporting by Krishna N. Das Editing by Robert Birsel)