High Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Household Transmission Rates Detected by Dense Saliva Sampling.

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.

QTc Prolongation in COVID-19 Patients Using Chloroquine.

Chloroquine is used in the treatment of patients with COVID-19 infection, although there is no substantial evidence for a beneficial effect. Chloroquine is known to prolong the QRS and QTc interval on the ECG. To assess the effect of chloroquine on QRS and QTc intervals in COVID-19 patients, we included all inpatients treated with chloroquine for COVID-19 in the Spaarne Gasthuis (Haarlem/Hoofddorp, the Netherlands) and had an ECG performed both in the 72 h before and during or at least 48 h after treatment. We analyzed the (change in) QRS and QTc interval using the one-sample t-test. Of the 106 patients treated with chloroquine, 70 met the inclusion criteria. The average change in QRS interval was 6.0 ms (95% CI 3.3-8.7) and the average change in QTc interval was 32.6 ms (95% CI 24.9-40.2) corrected with the Bazett's formula and 38.1 ms (95% CI 30.4-45.9) corrected with the Fridericia's formula. In 19 of the 70 patients (27%), the QTc interval was above 500 ms after start of chloroquine treatment or the change in QTc interval was more than 60 ms. A heart rate above 90 bpm, renal dysfunction, and a QTc interval below 450 ms were risk factors for QTc interval prolongation. Chloroquine prolongs the QTc interval in a substantial number of patients, potentially causing rhythm disturbances. Since there is no substantial evidence for a beneficial effect of chloroquine, these results discourage its use in COVID-19 patients.