by inhaling aerosol or droplets from infected individuals. Such particles also contaminate surfaces, creating a
potential surface-transmission pathway.
Methods: A fast acoustic biosensor with an antifouling nano-coating was introduced to detect severe acute
respiratory syndrome coronavirus 2 (SARS-CoV-2) on exposed surfaces in the Prague Public Transport System.
Samples were measured directly without pre-treatment. Results with the sensor gave excellent agreement with
parallel quantitative reverse-transcription polymerase chain reaction (qRT-PCR) measurements on 482 surface
samples taken from actively used trams, buses, metro trains and platforms between 7 and 9 April 2021, in the
middle of the lineage Alpha SARS-CoV-2 epidemic wave when 1 in 240 people were COVID-19 positive in Prague.
Results: Only ten of the 482 surface swabs produced positive results and none of them contained virus particles
capable of replication, indicating that positive samples contained inactive virus particles and/or fragments.
Measurements of the rate of decay of SARS-CoV-2 on frequently touched surface materials showed that the virus did
not remain viable longer than 1–4 h. The rate of inactivation was the fastest on rubber handrails in metro escalators
and the slowest on hard-plastic seats, window glasses and stainless-steel grab rails. As a result of this study, Prague
Public Transport Systems revised their cleaning protocols and the lengths of parking times during the pandemic.
Conclusions: Our findings suggest that surface transmission played no or negligible role in spreading SARS-CoV-2
in Prague. The results also demonstrate the potential of the new biosensor to serve as a complementary screening
tool in epidemic monitoring and prognosis.
- Biosensor Technologies