Indoor Spreading and Infectivity of SARS-CoV-2 Detected in Air and on Surfaces After Speaking or Singing of Symptomatic Individuals

Abstract

This observational experimental study was aimed at measuring SARS-CoV-2 dispersion via air and deposition onto surfaces in indoor spaces at short range (0.8 m) and long range (4.0 m) during the speaking and singing of mildly symptomatic COVID-19 patients. Ten patients were invited to sing and speak in unventilated rooms. Air and surface samples were taken and analyzed for SARS-CoV-2 by qPCR and cell culture assay. Seventy-three of 120 air samples and 2 of 80 surface samples tested positive by qPCR. Concentrations were too low to be quantified. Culturing to confirm infectivity was unsuccessful for all samples. High nasal virus concentration in patients, a high number of symptoms, and short symptom duration correlated with a higher probability of PCR-positive air samples. Impingers were significantly more effective air samplers than impactors. No significant effect was found for patient age, oropharyngeal virus concentration, the presence of systemic symptoms, vaccination status, the number of coughs during measurements, room temperature, humidity, time, proximity, respiratory activity, or voice amplitude during experiments. Two supporting experiments were performed on aerosol dispersion and sampler equipment tests. They confirmed that aerosols spread throughout the room homogeneously and that selected sampler equipment can detect genetic material from environmental samples. This study adds to the body of evidence regarding the dispersion of SARS-CoV-2 RNA in range of a few meters indoors.