A break from wastewater articles! “Longitudinal monitoring of SARS-CoV-2 RNA on high-touch surfaces in a community setting“. There’s not actually been a ton of articles about fomites recently… this appears less and less likely to be a source of transmission for SARS-CoV-2 although we certainly wouldn’t want to rule it out. It is, after all, pretty hard to prove. This study looked at a few hundred high-touch surfaces and found ~8% were positive which seems to be in line with other published studies so far. They make the argument that surfaces might even be a better leading indicator of community spread than wastewater which is certainly a controversial position at this point. The authors perform a risk assessment that I’m not totally sold on… there are just too many unknowns in a model for transmission risk from surfaces at this point. Abstract below:
Environmental surveillance of surface contamination is an unexplored tool for understanding transmission of SARS-CoV-2 in community settings. We conducted longitudinal swab sampling of high-touch non-porous surfaces in a Massachusetts town during a COVID-19 outbreak from April to June 2020. Twenty-nine of 348 (8.3 %) surface samples were positive for SARS-CoV-2, including crosswalk buttons, trash can handles, and door handles of essential business entrances (grocery store, liquor store, bank, and gas station). The estimated risk of infection from touching a contaminated surface was low (less than 5 in 10,000), suggesting fomites play a minimal role in SARS-CoV-2 community transmission. The weekly percentage of positive samples (out of n=33 unique surfaces per week) best predicted variation in city-level COVID-19 cases using a 7-day lead time. Environmental surveillance of SARS-CoV-2 RNA on high-touch surfaces could be a useful tool to provide early warning of COVID-19 case trends.