NEW DELHI/BENGALURU : Indian airlines started delivering batches of Covid-19 vaccines nationwide on Tuesday, preparing for the launch of a campaign to offer shots to 1.3 billion people, in what officials call the world's biggest vaccination drive.Vaccinations are set to begin on Saturday in an effort that authorities hope will see 300 million high-risk people inoculated over the next six to eight months.Also Read | How plant meat is coming of age in IndiaFirst to get the vaccine will be 30 million health and other frontline workers, followed by about 270 million older than 50 or deemed high-risk.Airlines were due to deliver 5.65 million vaccine doses on Tuesday to various cities, Aviation Minister Hardeep Singh Puri said on.