401. Natural History of Shedding and Household Transmission of Severe Acute Respiratory Syndrome Coronavirus 2 Using Intensive High-Resolution Sampling

Abstract

Background In order to mitigate the spread of SARS-CoV-2 and the COVID-19 pandemic, public health officials have recommended self-isolation, self-quarantine of exposed household contacts (HHC), and mask use to limit viral spread within households and communities. While household transmission of SARS-CoV-2 is common, risk factors for HHC transmission are poorly understood. Methods In this prospective cohort study, we enrolled 37 households with at least one reverse transcription polymerase chain reaction-confirmed (RT-PCR) COVID-19 index case from March 2020 - March 2021, in order to calculate secondary attack rates (SAR) and define risk factors for secondary infections. Participants were tested daily for SARS-CoV-2 via RT-PCR, using self-collected lower nasal samples. Households were followed until all members tested negative for seven consecutive days. We collected demographics, medical conditions, relationship to index case, and socioeconomic indicators. Subgroup data analysis was conducted and stratified by positivity status. Results Of 99 enrolled participants, 37 were index cases and 62 were household contacts (HHC), of whom 25 HHC were infected (40.3%). Secondary attack rate (SAR) was highest among adults caring for a parent (n=4/4, 100%) and parents of index cases (5/10, 50%). Households whose income came from service work had greater risk of transmission compared to households whose primary income was technology (n=5/7; 71.4% vs 3/8; 37.5% respectively). Pediatric contacts were at lower risk of infection when compared to adult contacts (n=5/18, 27.8% vs n=20/44, 45.5% respectively). Conclusion This study suggests that household transmission represents a key source of community-based infection of SARS-CoV-2. Allocating resources for education/training regarding prevention among infected individuals and their close contacts will be critical for control of future outbreaks of SARS-CoV-2. Disclosures All Authors: No reported disclosures

Challenges in Harnessing Shared Within-Host Severe Acute Respiratory Syndrome Coronavirus 2 Variation for Transmission Inference

“…The first was a prospective household transmission study, in which index cases with at least 1 reverse-transcription quantitative polymerase chain reaction (RT-qPCR)-confirmed SARS-CoV-2 test were enrolled along with household members. Participants were tested daily for SARS-CoV-2 ribonucleic acid (RNA) via RT-qPCR, using self-collected lower nasal swabs, and households were followed until all members tested negative for 7 consecutive days [ 18 ]. The second was a randomized, single-blind, placebo-controlled trial of Peginterferon Lambda-1a (Lambda) for reducing the duration of viral shedding or symptoms [ 19 ] in which oropharyngeal swabs were collected for 28 days after enrollment.…”

Shared within-host SARS-CoV-2 variation in households

“…We assembled a collection of samples from four prospective SARS-CoV-2 research studies: (a) a prospective household transmission study, in which index cases with at least one reverse transcription quantitative polymerase chain reaction-confirmed (RT-qPCR) SARS-CoV-2 test were enrolled along with household members. Participants were tested daily for SARS-CoV-2 RNA via RT-qPCR, using self-collected lower nasal swabs, and households were followed until all members tested negative for seven consecutive days[16]. (b) A randomized, single-blind, placebo-controlled trial of Peginterferon Lambda-1a (Lambda) for reducing the duration of viral shedding or symptoms[17] in which oropharyngeal swabs were collected for 28 days following enrollment.…”