Ricerc@Sapienza

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) environmental
contamination occurs through droplets and biological fluids released in the surroundings
from patients or asymptomatic carriers. Surfaces and objects contaminated
by saliva or nose secretions represent a risk for indirect transmission of coronavirus disease
2019 (COVID-19). We assayed surfaces from hospital and living spaces to identify
the presence of viral RNA and the spread of fomites in the environment. Anthropic contamination
by droplets and biological fluids was monitored by detecting the microbiota
signature using multiplex quantitative real-time PCR (qPCR) on selected species and
massive sequencing on 16S amplicons. A total of 92 samples (flocked swabs) were collected
from critical areas during the pandemic, including indoor (three hospitals and
three public buildings) and outdoor surfaces exposed to anthropic contamination (handles
and handrails, playgrounds). Traces of biological fluids were frequently detected in
spaces open to the public and on objects that are touched with the hands (.80%).
However, viral RNA was not detected in hospital wards or other indoor and outdoor
surfaces either in the air system of a COVID hospital but only in the surroundings
of an infected patient, in consistent association with droplet traces and fomites.
Handled objects accumulated the highest level of multiple contaminations by saliva,
nose secretions, and fecal traces, further supporting the priority role of handwashing
in prevention. In conclusion, anthropic contamination by droplets and biological
fluids is widespread in spaces open to the public and can be traced by
qPCR. Monitoring fomites can support evaluation of indirect transmission risks for
coronavirus or other flu-like viruses in the environment.