Abstract
Background: Understanding the dynamics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) household transmission is important for adequate infection control measures in this ongoing pandemic.
Methods: Households were enrolled upon a polymerase chain reaction-confirmed index case between October and December 2020, prior to the coronavirus disease 2019 vaccination program. Saliva samples were obtained by self-sampling at days 1, 3, 5, 7, 10, 14, 21, 28, 35, and 42 from study inclusion. Nasopharyngeal swabs (NPS) and oropharyngeal swabs (OPS) were collected by the research team at day 7 and capillary blood samples at day 42. Household secondary attack rate (SAR) and per-person SAR were calculated based on at least 1 positive saliva, NPS, OPS, or serum sample. Whole genome sequencing was performed to investigate the possibility of multiple independent SARS-CoV-2 introductions within a household.
Results: Eighty-five households were included consisting of 326 (unvaccinated) individuals. Comparable numbers of secondary cases were identified by saliva (133/241 [55.2%]) and serum (127/213 [59.6%]). The household SAR was 88.2%. The per-person SAR was 64.3%. The majority of the secondary cases tested positive in saliva at day 1 (103/150 [68.7%]). Transmission from index case to household member was not affected by age or the nature of their relationship. Phylogenetic analyses suggested a single introduction for the investigated households.
Conclusions: Households have a pivotal role in SARS-CoV-2 transmission. By repeated saliva self-sampling combined with NPS, OPS, and serology, we found the highest SARS-CoV-2 household transmission rates reported to date. Salivary (self-) sampling of adults and children is suitable and attractive for near real-time monitoring of SARS-CoV-2 transmission in this setting.
Keywords: COVID-19; SARS-CoV-2; household transmission; saliva.
【저자키워드】 COVID-19, SARS-CoV-2, household transmission, Saliva., 【초록키워드】 coronavirus disease, infection control, Saliva, Coronavirus disease 2019, coronavirus, vaccination, pandemic, serology, children, severe acute respiratory syndrome Coronavirus, secondary attack rate, polymerase chain reaction, serum, SARS-CoV-2 transmission, Whole genome sequencing, household, nasopharyngeal swabs, attack rate, oropharyngeal swab, Research, Households, understanding, household transmission, age, Swab, phylogenetic analyses, SAR, saliva sample, index case, acute respiratory syndrome, Real-time monitoring, acute respiratory syndrome coronavirus, acute respiratory syndrome coronavirus 2, oropharyngeal swabs, measure, study inclusion, saliva samples, positive, capillary blood, capillary blood samples, serum sample, secondary cases, secondary case, NPs, repeated, independent, polymerase chain, enrolled, highest, tested, collected, reported, investigated, was performed, calculated, majority, suggested, analysis, individuals, not affected, 【제목키워드】 coronavirus 2, sampling, respiratory, Rate, Dense,