As of August 16, 8.8 % of India's population has been fully vaccinated against COVID-19, while 30.9% has received at least one dose. Earlier this month, the country saw a huge achievement in coverage -- the 50-crore mark in vaccine doses administered was reached. But as India continues to report over 30,000 new cases a day, and concerns mount about the Delta variant in other parts of the world, how much faster does our vaccination campaign need to be? Can we meet the government's estimated deadline of covering all beneficiaries over the age of 18 by December 2021, and do we have enough supply to meet this target? Can our two main vaccines, Covishield and Covaxin be mixed for better results? And what is the latest on that tricky subject, herd immunity? Guest: Dr. K Srinath Reddy, president, Public Health Foundation of India Host: Zubeda Hamid Write to us at socmed4@thehindu.co.in