Covid19-Sources

Table 4. Infection risk probability [%] results for any one individual in a group of 20 people (with and without universal FFP2 masking) after 8 hours of exposure on the coldest day (12th of January, left) and the warmest day (30th of June, right) of the academic year.ScenariosCold day risk (12th January) [%]Warm day risk (30th June) [%]Without masksWith masksWithout masksWith masks1. BC10027100272. MPIC-MEV 10 ℓ/s(p)4744743. MPIC-MEV 20 ℓ/s(p)3023024. AHU-HRV 10 ℓ/s(p)5755755. AHU-HRV 20 ℓ/s(p)3733836. NV-T4237277. NV-P595595 As might be expected, the results (Table 4) show the highest risk of infection occurs in scenario 1 as there is no active ventilation.

SARS-CoV-2 induces long-term alterations in Mac phenotypeTo explore long-term SARS-CoV-2 effects on innate immunity, we infected 25 cynomolgus macaques with wild-type (hereafter WTM, n = 15), Omicron BA.1 (n = 6) and Omicron BA.2 (n = 4) variants (hereafter OM), along with six noninfected macaques as controls (HC; Fig. 1a and Extended Data Table 1). Viral RNA loads peaked in nasal and tracheal swabs at day 3 postinfection (p.i.) in WTM and OM (7.9 × 108 and 2.78 × 107 copies per ml, respectively; Fig. 1a). Viral RNA was higher in the nasal swabs from WTM than OM (Extended Data Fig. 1a). By day 21, all macaques tested negative for SARS-CoV-2 RNA in nasal and tracheal swabs and remained negative by this readout up to 18 months p.i. (Fig. 1a). Immune responses were assessed at a median of 221 d p.i, with the analysis potentially extending to day 479 (Supplementary Table 1). Plasma immunoglobulin G (IgG) and IgA reactivities against spike and receptor-binding domain (RBD) were comparable in WTM and OM (Fig. 1b and Extended Data Fig. 1b). Inflammatory cytokines (interleukin (IL)-6, IL-18, IL-23, CXCL10) were higher in WTM and OM at 221 d.p.i. compared to HC (Extended Data Fig. 1c), suggesting lasting inflammation.

Overall seroprevalence was 53% (95% confidence interval (CI) 48–58%) among household contacts. The estimated household secondary attack rate is 34% (95% CI 5–75%). Mask wearing by the index case is associated with the household transmission risk reduction by 67% (adjusted odds ratio = 0.33 with 95% CI: 0.09–0.75) and not sharing bedroom with the index case is associated with the risk reduction of household transmission by 78% (adjusted odds ratio = 0.22 with 95% CI 0.10–0.41). The estimated distribution of household secondary attack rates is highly heterogeneous across index cases, with 30% of index cases being the source for 80% of secondary cases.