Insights into household transmission of SARS-CoV-2 from a population-based serological survey
Qifang Bi, Justin Lessler, Isabella Eckerle, Stephen A. Lauer, Laurent Kaiser, Nicolas Vuilleumier, Derek A. T. Cummings, Antoine Flahault, Dusan Petrovic, Idris Guessous, Silvia Stringhini, Andrew S. Azman, SEROCoV-POP Study Group, Silvia Stringhini, Idris Guessous, Hélène Baysson, Prune Collombet, David De Ridder, Paola D’Ippolito, Matilde D’asaro-Aglieri Rinella, Yaron Dibner, Nacira El Merjani, Natalie Francioli, Marion Frangville, Kailing Marcus, Chantal Martinez, Natacha Noël, Francesco Pennacchio, Javier Perez‐Saez, Dusan Petrovic, A. Picazio, Alborz Pishkenari, Giovanni Piumatti, Jane Portier, Caroline Pugin, Barinjaka Rakotomiaramanana, Aude Richard, Lilas Salzmann-Bellard, Stephanie Schrempft, María-Eugenia Zaballa, Zoé Waldmann, Ania Wisniak, Alioucha Davidovic, Joséphine Duc, Julie Guérin, Fanny Lombard, Manon Will, Antoine Flahault, Isabelle Arm Vernez, Olivia Keiser, Loan Mattera, Magdalena Schellongova, Laurent Kaiser, Isabella Eckerle, Pierre Lescuyer, Benjamin Meyer, Géraldine Poulain, Nicolas Vuilleumier, Sabine Yerly, François Chappuis, Sylvie Welker, Delphine S. Courvoisier, Laurent Gétaz, Mayssam Nehme, Febronio Pardo, Guillemette Violot, Samia Hurst, Philippe Matute, Jean-Michel Maugey, Didier Pittet, Arnaud G. L’Huillier, Klara M. Posfay‐Barbe, Jean‐François Pradeau, Michel Tacchino, Didier Trono
Abstract
Understanding the risk of infection from household- and community-exposures and the transmissibility of asymptomatic infections is critical to SARS-CoV-2 control. Limited previous evidence is based primarily on virologic testing, which disproportionately misses mild and asymptomatic infections. Serologic measures are more likely to capture all previously infected individuals. We apply household transmission models to data from a cross-sectional, household-based population serosurvey of 4,534 people ≥5 years from 2,267 households enrolled April-June 2020 in Geneva, Switzerland. We found that the risk of infection from exposure to a single infected household member aged ≥5 years (17.3%,13.7-21.7) was more than three-times that of extra-household exposures over the first pandemic wave (5.1%,4.5-5.8). Young children had a lower risk of infection from household members. Working-age adults had the highest extra-household infection risk. Seropositive asymptomatic household members had 69.4% lower odds (95%CrI,31.8-88.8%) of infecting another household member compared to those reporting symptoms, accounting for 14.5% (95%CrI, 7.2-22.7%) of all household infections.