Dr Samiran Panda said drones are being used to deliver doses in mountainous states in the country's north-east.
India aims to vaccinate all eligible citizens by the end of 2021 but experts say the drive needs to pick up a consistent pace to meet the target.
India has so far given more than 925 million doses of three approved jabs.
About 70% of the country's eligible population 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, and more than 440,000 deaths - behind the US and Brazil.