India administered more than 20 million Covid vaccine doses in a day on Friday in a record-breaking effort to mark PM Narendra Modi's 71st birthday.
India aims to vaccinate all eligible Indians by the end of 2021 but experts say the drive needs to pick up a consistent pace to meet the target.
More than half of India's eligible population - some 588 million people - have received at least one dose of a Covid vaccine, according to official data.
India has reported more than 33 million Covid cases, second only to the US. The country is also only the third in the world to record more than 440,000 deaths - behind the US and Brazil.
India gave six million jabs on an average every day in August, compared to 4.3 million daily jabs in July, according to official data. But September has seen a rise with more than 7.4 million doses administered daily.
Experts say record-breaking days are encouraging but vaccination rates need to rise consistently. They estimate that India needs to give more than 10 million doses a day to fully vaccinate all eligible adults by the end of 2021.