Increased transmissibility of SARS-CoV-2 lineage B.1.1.7 by age and viral load
Frederik Plesner Lyngse, Kåre Mølbak, Robert Skov, Lasse Engbo Christiansen, Laust Hvas Mortensen, Mads Albertsen, Camilla Holten Møller, Tyra Grove Krause, Morten Rasmussen, Thomas Yssing Michaelsen, Marianne Voldstedlund, Jannik Fonager, Nina R. Steenhard, AAU Coordination, Jakob Brandt, Simon Knuttson, Emil A. Sørensen, Thomas Bygh Nymann Jensen, Trine Sørensen, Celine Petersen, Clarisse Chiche-Lapierre, Frederik Teilfeldt Hansen, Emilio F. Collados, Amalie Berg, Susanne R. Bielidt, Sebastian Mølvang Dall, Erika Dvarionaite, Susan Hove Hansen, Vibeke Børsholt Rudkjøbing, Trine B. Nicolajsen, Wagma Saei, Stine Karstenskov Østergaard, AAU Bioinformatics, Thomas Yssing Michaelsen, Vang Quy Le, Mantas Sereika, Rasmus Hansen Kirkegaard, Kasper Skytte Andersen, Martin Hjorth Andersen, AAU CLAUDIA/IT, Karsten Kryger Hansen, Mads Boye, Mads P. Bach, Peter Dissing, Anton Drastrup-Fjordbak, Michael Collin, Finn Büttner, AAU Legal and Admin, Susanne Andersen, L. Otte, AAU SUND, Martin Bøgsted, Rasmus Froberg Brøndum, AAU Computer Science, Katja Hose, Tomer Sagi, Miroslav Pakanec, Statens Serum Institut, Anders Fomsgaard, Søren Michael Karst, Vithiagaran Gunlan, Marc Bennedbæk, Raphael N. Sieber, Kirsten Ellegaard, Anna Cäcilia Ingham, Thor Bech Johannesen, Martín Basterrechea, Berit Lilje, Kim Lee Ng, Sofie Marie Edslev, Sharmin Baig, Marc Stegger, Povilas Matusevicius, Lars Christoffersen, Man‐Hung Eric Tang, Christina Wiid Svarrer, Nour Saad Al-Tamimi, Marie Bækvad‐Hansen, Jonas Byberg-Grauholm, Mette T. Christiansen, Karen Mare Jørgensen, Nicolai Balle Larsen, Arieh S. Cohen, Henrik Krarup, David Fuglsang-Damgaard, Mette Mølvadgaard, Marc T. K. Nielsen, Kristian Schønning, Martin Schou Pedersen, Rasmus L. Marvig, Nikolai Kirkby, Uffe Vest Schneider, José Alfredo Samaniego Castruita, Nana Gry Jacobsen, Christian Ø. Andersen, Mette T. Christiansen, Ole H. Larsen, Kristian Alsbjerg Skipper, Søren Vang, Kurt Handberg
Abstract
New lineages of SARS-CoV-2 are of potential concern due to higher transmissibility, risk of severe outcomes, and/or escape from neutralizing antibodies. Lineage B.1.1.7 (the Alpha variant) became dominant in early 2021, but the association between transmissibility and risk factors, such as age of primary case and viral load remains poorly understood. Here, we used comprehensive administrative data from Denmark, comprising the full population (January 11 to February 7, 2021), to estimate household transmissibility. This study included 5,241 households with primary cases; 808 were infected with lineage B.1.1.7 and 4,433 with other lineages. Here, we report an attack rate of 38% in households with a primary case infected with B.1.1.7 and 27% in households with other lineages. Primary cases infected with B.1.1.7 had an increased transmissibility of 1.5-1.7 times that of primary cases infected with other lineages. The increased transmissibility of B.1.1.7 was multiplicative across age and viral load.