Presence of SARS-CoV-2 in HEPA Filters of Portable Air Cleaners

A method for determining the presence of SARS-CoV-2 RNA in HEPA filters from portable air cleaners (PACs) have been developed and validated. Herein, a monitoring survey was conducted for 13 weeks in three indoor environments, school, nursery and a household of a socio-sanitary center in Ciudad Real, Spain. In this study, we employed environmental monitoring by RT-PCR of the presence of SARS-CoV-2 in HEPA filters and other surfaces of these indoor spaces for a selective screening in asymptomatic population groups. The aim was to limit outbreaks in an early stage. Only one HEPA filter tested positive in the socio-sanitary center. After analysis by RT-PCR of SARS-CoV-2 in residents and healthcare workers, one worker tested positive. Therefore, this study provides direct evidence of virus-containing aerosols trapped in HEPA filters and the possibility of using these PACs for environmental monitoring of SARS-CoV-2 while they remove airborne aerosols and trap the virus. © 2022 17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022. All rights reserved.

ADAPTIVE TEST ALLOCATION for OUTBREAK DETECTION and TRACKING in SOCIAL CONTACT NETWORKS

We present a general framework for adaptive allocation of viral tests in social contact networks and arbitrary epidemic models. We pose and solve several complementary problems. First, we consider the design of a social sensing system whose objective is the early detection of a novel epidemic outbreak. In particular, we propose an algorithm to select a subset of individuals to be tested in order to detect the onset of an epidemic outbreak as fast as possible. We pose this problem as a hitting time probability maximization problem and use submodularity optimization and Monte Carlo techniques to obtain solutions with explicit quality guarantees. Second, once an epidemic outbreak has been detected, we consider the problem of using the data from the sensing system to obtain estimates of the initial patient and the current status of the epidemic. Finally, we consider the problem of adaptively distributing viral tests over time in order to maximize the information gained about the current state of the epidemic. We formalize this problem in terms of mutual information and propose an adaptive allocation strategy with quality guarantees. For these problems, we derive analytical solutions for any stochastic compartmental epidemic model with Markovian dynamics, as well as efficient Monte Carlo-based algorithms for non-Markovian dynamics or large networks. We illustrate the performance of the proposed framework in numerical experiments involving a model of COVID-19 applied to a real human contact network. © 2022 Society for Industrial and Applied Mathematics

Infection with coronavirus disease 19 (COVID-19) in healthcare personnel with exposure to COVID-19

Background: As of June 2, 2020, 67,113 cases and 321 deaths due to Coronavirus Disease 19 (COVID-19) have been reported in healthcare personnel (HCP) in the United States. Given the close contact of HCP with individuals with COVID-19, it is important to quantify the risk of acquiring COVID-19 in the healthcare setting. Methods: We conducted a retrospective cohort study of HCP exposed to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) at our academic medical center from March 15, 2020 to May 16, 2020. Exposure during the study period was defined as having contact with patients or other HCP with COVID-19 within 6 feet of distance for at least 90 seconds when HCP's eyes, nose, or mouth were not covered. HCP with exposures were monitored for symptoms consistent with COVID-19 for 14 days from last exposure and those who developed symptoms were tested for SARSCoV- 2 using RT-PCR. Results: We identified 33 exposure events;19 of which were patient-to-HCP exposures and 14 of which were HCP-to-HCP exposures. These 33 events resulted in 959 exposed HCP among whom 238 (25%) developed one or more symptoms of COVID-19 and required SARS-CoV-2 RT-PCR testing. Testing was performed at 7.1 ± 5.0 (mean ± SD) days from exposure. Of the 238 HCP who were tested, 82% were female and 49% were registered nurses (Table 1). Five HCP tested positive for SARSCoV- 2 by RT-PCR, but one was presumed to have acquired the disease from a household member with confirmed COVID-19. Among the four HCP who were infected due to occupational exposure, three were nurses while one was an environmental service worker (Table 1). Conclusion: Despite exposures among HCP, the risk of acquiring symptomatic COVID-19 in the healthcare setting was low with less than 1% of HCP with occupational exposure subsequently diagnosed with COVID-19. With the definition of exposure now changed to at least 15 minutes of close contact without personal protective equipment, we anticipate fewer exposures at our healthcare facility and that much of COVID-19 transmission affecting HCP are due to community exposures.