WP 2: Surface Sampling

Led by Public Health England

WP2 will focus on measuring COVID-19 and human respiratory associated agents on surfaces and air in transport systems. It aims to understand both the prevalence of SARS-CoV-2 and other respiratory microorganisms and to also test the effect of selected mitigation strategies on microbial contamination in public transport environments.

We obtain monthly microbial samples from a range of transport vehicles to determine the background presence of SARS-CoV-2, together with targeted sampling when and where an outbreak cluster is suspected. As we expect the prevalence of SARS-CoV-2 to be low, we are also looking for presence of other respiratory viruses and the level of bacterial contamination as markers to indicate risk and surface ‘cleanliness’

Our sampling methodology was developed through an initial pilot study which involved a PHE team surface sampling common touch sites such as handrails and buttons. Along with analysis of results, training material has been developed to allow transport operator staff to carry out sampling independently. Transport operators involved in the project return the swabs to PHE for analysis. Air samples are also taken using personal and static air samplers.

Surface Sampling

A swab being taken from a train toilet door. Picture credit: Public Health England

The impacts of mitigation strategies will be assessed using two experimental approaches.

One is through In-vitro assessment, looking at the efficacy of mitigation strategies under controlled laboratory conditions. The survival of SARS-CoV-2 (and surrogates) on surfaces found in public transport, will be assessed before and after treatment with an ‘anti-viral’ coating or the application of UV. The second experimental approach is in conjunction with WP5, through in-vivo assessment that uses safe or naturally occurring respiratory micro-organisms as tracers in a controlled setting. Data from these experiments will directly inform the viral survival parameters in the WP1 models.

Updated Wednesday 28 April 2021