SARS-CoV-2 surface and air contamination in an acute healthcare setting during the first and second pandemic waves.

ABSTRACT

BACKGROUND: Surfaces and air in healthcare facilities can be contaminated with SARS-CoV-2. In a previous study, we identified SARS-CoV-2 RNA on surfaces and air in our hospital during the 'first wave' of the COVID-19 pandemic (April 2020). AIM: To explore whether the profile of SARS-CoV-2 surface and air contamination had changed between April 2020 and January 2021. METHODS: A prospective, cross-sectional, observational study in a multisite London hospital. In January 2021, surface and air samples were collected from comparable areas to those sampled in April 2020 comprising six clinical areas and a public area. SARS-CoV-2 was detected using RT-PCR and viral culture. Sampling was additionally undertaken in two wards with only natural ventilation. The ability of the prevalent variants at the time of the study to survive on dry surfaces was evaluated. FINDINGS: No viable virus was recovered from surfaces or air. 5% (14) of 270 surfaces and 4% (1) of 27 air samples were positive for SARS-CoV-2, which was significantly lower than in April 2020 (52% (114) of 218 of surfaces and 48% (13) of 27 air samples (p<0.001, Fisher's Exact Test)). There was no clear difference in the proportion of surfaces and air samples positive for SARS-CoV-2 RNA based on the type of ventilation in the ward. All variants tested survived on dry surfaces for at least 72 hours with a <3-log10 reduction in viable count. CONCLUSION: Our study suggests that enhanced infection prevention measures have reduced the burden of SARS-CoV-2 RNA on surfaces and air in healthcare.