TY - JOUR T1 - Genomic characterization and epidemiology of an emerging SARS-CoV-2 variant in Delhi, India. JF - Science Y1 - 2021 A1 - Dhar, Mahesh S A1 - Marwal, Robin A1 - Vs, Radhakrishnan A1 - Ponnusamy, Kalaiarasan A1 - Jolly, Bani A1 - Bhoyar, Rahul C A1 - Sardana, Viren A1 - Naushin, Salwa A1 - Rophina, Mercy A1 - Mellan, Thomas A A1 - Mishra, Swapnil A1 - Whittaker, Charles A1 - Fatihi, Saman A1 - Datta, Meena A1 - Singh, Priyanka A1 - Sharma, Uma A1 - Ujjainiya, Rajat A1 - Bhatheja, Nitin A1 - Divakar, Mohit Kumar A1 - Singh, Manoj K A1 - Imran, Mohamed A1 - Senthivel, Vigneshwar A1 - Maurya, Ranjeet A1 - Jha, Neha A1 - Mehta, Priyanka A1 - A, Vivekanand A1 - Sharma, Pooja A1 - Vr, Arvinden A1 - Chaudhary, Urmila A1 - Soni, Namita A1 - Thukral, Lipi A1 - Flaxman, Seth A1 - Bhatt, Samir A1 - Pandey, Rajesh A1 - Dash, Debasis A1 - Faruq, Mohammed A1 - Lall, Hemlata A1 - Gogia, Hema A1 - Madan, Preeti A1 - Kulkarni, Sanket A1 - Chauhan, Himanshu A1 - Sengupta, Shantanu A1 - Kabra, Sandhya A1 - Gupta, Ravindra K A1 - Singh, Sujeet K A1 - Agrawal, Anurag A1 - Rakshit, Partha A1 - Nandicoori, Vinay A1 - Tallapaka, Karthik Bharadwaj A1 - Sowpati, Divya Tej A1 - Thangaraj, K A1 - Bashyam, Murali Dharan A1 - Dalal, Ashwin A1 - Sivasubbu, Sridhar A1 - Scaria, Vinod A1 - Parida, Ajay A1 - Raghav, Sunil K A1 - Prasad, Punit A1 - Sarin, Apurva A1 - Mayor, Satyajit A1 - Ramakrishnan, Uma A1 - Palakodeti, Dasaradhi A1 - Seshasayee, Aswin Sai Narain A1 - Bhat, Manoj A1 - Shouche, Yogesh A1 - Pillai, Ajay A1 - Dikid, Tanzin A1 - Das, Saumitra A1 - Maitra, Arindam A1 - Chinnaswamy, Sreedhar A1 - Biswas, Nidhan Kumar A1 - Desai, Anita Sudhir A1 - Pattabiraman, Chitra A1 - Manjunatha, M V A1 - Mani, Reeta S A1 - Arunachal Udupi, Gautam A1 - Abraham, Priya A1 - Atul, Potdar Varsha A1 - Cherian, Sarah S AB -

Delhi, the national capital of India, has experienced multiple SARS-CoV-2 outbreaks in 2020 and reached population seropositivity of over 50% by 2021. During April 2021, the city became overwhelmed by COVID-19 cases and fatalities, as a new variant B.1.617.2 (Delta) replaced B.1.1.7 (Alpha). A Bayesian model explains the growth advantage of Delta through a combination of increased transmissibility and reduced sensitivity to immune responses generated against earlier variants (median estimates; ×1.5-fold, 20% reduction). Seropositivity of an employee and family cohort increased from 42% to 87.5% between March and July 2021, with 27% reinfections, as judged by increased antibody concentration after a previous decline. The likely high transmissibility and partial evasion of immunity by the Delta variant contributed to an overwhelming surge in Delhi.

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