It took India a little over nine months to achieve the one billion vaccination milestone, but the next billion doses will only take about three to four months - about one-third the time -- according to Dr NK Arora, who heads the National Expert Group on Vaccine Administration. Speaking to NDTV on the day India achieved the one billion jabs milestone, Dr Arora said, "How do I reach 100% of the population by the end of the year? At least one dose we should be able to give most of the adults by the end of the year and within the next 4-6 weeks second doses will also be given."