Detection of air and surface contamination by SARS-CoV-2 in hospital rooms of infected patients

Chia, Po Ying; Coleman, Kristen Kelli; Tan, Yian Kim; Ong, Sean Wei Xiang; Gum, Marcus; Lau, Sok Kiang; Lim, Xiao Fang; Lim, Ai Sim; Sutjipto, Stephanie; Lee, Pei Hua; Son, Than The; Young, Barnaby Edward; Milton, Donald K.; Gray, Gregory C.; Schuster, Stephan; Barkham, Timothy; De, Partha Pratim; Vasoo, Shawn; Chan, Monica; Ang, Brenda Sze Peng; Tan, Boon Huan; Leo, Yee-Sin; Ng, Oon-Tek; Wong, Michelle Su Yen; Marimuthu, Kalisvar

Understanding the particle size distribution in the air and patterns of environmental contamination of SARS-CoV-2 is essential for infection prevention policies. Here we screen surface and air samples from hospital rooms of COVID-19 patients for SARS-CoV-2 RNA. Environmental sampling is conducted in three airborne infection isolation rooms (AIIRs) in the ICU and 27 AIIRs in the general ward. 245 surface samples are collected. 56.7% of rooms have at least one environmental surface contaminated. High touch surface contamination is shown in ten (66.7%) out of 15 patients in the first week of illness, and three (20%) beyond the first week of illness (p = 0.01, χ(2) test). Air sampling is performed in three of the 27 AIIRs in the general ward, and detects SARS-CoV-2 PCR-positive particles of sizes >4 µm and 1–4 µm in two rooms, despite these rooms having 12 air changes per hour. This warrants further study of the airborne transmission potential of SARS-CoV-2.