Portal de Periódicos da CAPES

Household transmission of SARS-CoV-2 Omicron variant of concern subvariants BA.1 and BA.2 in Denmark

2022; Nature Portfolio; Volume: 13; Issue: 1 Linguagem: Inglês

10.1038/s41467-022-33498-0

2041-1723

Frederik Plesner Lyngse, Carsten Kirkeby, Matthew Denwood, Lasse Engbo Christiansen, Kåre Mølbak, Camilla Holten Møller, Robert Skov, Tyra Grove Krause, Morten Rasmussen, Raphael N. Sieber, Thor Bech Johannesen, Troels Lillebæk, Jannik Fonager, Anders Fomsgaard, Frederik Trier Møller, Marc Stegger, Maria Overvad, Katja Spieß, Laust Hvas Mortensen,

SARS-CoV-2 detection and testing

SARS coronavirus 2 (SARS-CoV-2) continues to evolve and new variants emerge. Using nationwide Danish data, we estimate the transmission dynamics of SARS-CoV-2 Omicron subvariants BA.1 and BA.2 within households. Among 22,678 primary cases, we identified 17,319 secondary infections among 50,588 household contacts during a 1-7 day follow-up. The secondary attack rate (SAR) was 29% and 39% in households infected with Omicron BA.1 and BA.2, respectively. BA.2 was associated with increased susceptibility of infection for unvaccinated household contacts (Odds Ratio (OR) 1.99; 95%-CI 1.72-2.31), fully vaccinated contacts (OR 2.26; 95%-CI 1.95-2.62) and booster-vaccinated contacts (OR 2.65; 95%-CI 2.29-3.08), compared to BA.1. We also found increased infectiousness from unvaccinated primary cases infected with BA.2 compared to BA.1 (OR 2.47; 95%-CI 2.15-2.84), but not for fully vaccinated (OR 0.66; 95%-CI 0.57-0.78) or booster-vaccinated primary cases (OR 0.69; 95%-CI 0.59-0.82). Omicron BA.2 is inherently more transmissible than BA.1. Its immune-evasive properties also reduce the protective effect of vaccination against infection, but do not increase infectiousness of breakthrough infections from vaccinated individuals.