Coronavirus COVID-19 Update for July 30, 2020

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Diagnostics

Field-deployable, rapid diagnostic testing of saliva samples for SARS-CoV-2.
As we have previously noted, rapid and inexpensive diagnostic tests can change the landscape of this pandemic. Authors report the development and initial validation of a one-step, SARS-CoV-2 detection assay that can detect single-copy levels of virus directly from saliva using only a 1.5 mL microcentrifuge tube preloaded with a reaction mixture and a 30 min incubation in a heat block, without the need for RNA extraction or sample pretreatment. The method is based on significant modifications to Reverse Transcription Loop-mediated isothermal Amplification (RT-LAMP), a targeted nucleic acid amplification method.

Epidemiology

Age-Related Differences in Nasopharyngeal Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Levels in Patients With Mild to Moderate Coronavirus Disease 2019 (COVID-19)
This study examined 59,073 contacts of 5,706 COVID-19 patients in South Korea during January 20–March 27, 2020. The 5,706 index patients were grouped by age and the numbers of cases associated with that individual were identified. COVID-19 was detected in 11.8% of household contacts, and the rates were higher for contacts of children than for adults. The highest transmission rate, 18.6%, was observed for household contacts of school-aged children (10-19 years), and the lowest, 5.3%, for household contacts of children 0–9 years.
Contact Tracing during Coronavirus Disease Outbreak, South Korea, 2020
This study examined the presence of SARS-CoV-2 nucleic acids in nasopharyngeal swabs at a pediatric tertiary medical center in Chicago. The cohort, which included individuals less than a year of age to 65, all tested positive for SARS-CoV-2. Viral nucleic acid was detected by RT-PCR and the cycle threshold (CT) values for each individual were calculated. The results show that young children (less than 5 years old) have as much or more SARS-CoV-2 nucleic acids in their upper respiratory tracts compared with older children (5-17 years old) or adults (over 18). While infectious virus was not measured, these differences mean that young children could have 10 to 100 times more infectious virus in their upper respiratory tracts.