Viable SARS-CoV-2 Delta variant detected in aerosols in a residential setting with a self-isolating college student with COVID-19

Abstract

The B.1.617.2 (Delta) variant of SARS-CoV-2 emerged in India in October of 2020 and spread widely to over 145 countries, comprising over 99% of genome sequence-confirmed virus in COVID-19 cases of the United States (US) by September 2021. The rise in COVID-19 cases due to the Delta variant coincided with a return to in-person school attendance, straining COVID-19 mitigation plans implemented by educational institutions. Some plans required sick students to self-isolate off-campus, resulting in an unintended consequence: exposure of co-inhabitants of dwellings used by the sick person during isolation. We assessed air and surface samples collected from the bedroom of a self-isolating university student with mild COVID-19 for the presence of SARS-CoV-2. That virus' RNA was detected by real-time reverse-transcription quantitative polymerase chain reaction (rRT-qPCR) in air samples from both an isolation bedroom and a distal, non-isolation room of the same dwelling. SARS-CoV-2 was detected and viable virus was isolated in cell cultures from aerosol samples as well as from the surface of a mobile phone. Genomic sequencing revealed that the virus was a Delta variant SARS-CoV-2 strain. Taken together, the results of this work confirm the presence of viable SARS-CoV-2 within a residential living space of a person with COVID-19 and show potential for transportation of virus-laden aerosols beyond a designated isolation suite to other areas of a single-family home.

Keywords: Air sampling; Infectious; Virus culture; rRT-qPCR.

Fig. 1

Sampling site layout depicting sampling points and estimated flow direction when the intermittent HVAC system is running. This sketch represents the larger sampling environment and the region of the home serviced by the same air handling unit. A second air handler serviced the remaining portion of the home.

Fig. 2

Estimated SARS-CoV-2 GE per L of air per change in particle diameter [Δlog(Dp)] versus particle diameter fractionalization within (a) the volunteer isolation bedroom and (b) non-isolation bedroom. Bins depicted represent particle size fractions collected by the NIOSH bioaerosol sampler. Bins with no detected virus are listed with concentrations of 0 GE/L.