Princeton University — In one of the monthly series talks from Princeton University, Dr. Ramanan Laxminarayan discusses the major public health efforts in Andhra Pradesh and Tamil Nadu provinces in India, which enabled the tracing of 85,000 COVID-19 index cases and their 757,000 contacts, in one of the largest contact- tracing studies to date. The talk also highlights one of the important and surprising findings from the study implying that COVID-19 transmission was greater among groups of same-age categories.