War on Covid: How many people must India vaccinate to achieve herd immunity

India is currently witnessing a devastating surge of Covid-19 with record-breaking cases and deaths. Hindustan Times' Editor-in-chief, Sukumar Ranganathan in the latest edition of HT Insight explains how to achieve herd immunity among the people in the country. According to him, vaccination is the most effective way to combat this deadly virus. Watch the full video for more.