The Synergistic Effect of Time of Exposure, Distance and No Use of Personal Protective Equipment in the Determination of SARS-CoV-2 Infection: Results of a Contact Tracing Follow-Up Study in Healthcare Workers

Giuseppe La Torre, Mattia Marte, Carlo Maria Previte, Lavinia Camilla Barone, Filippo Picchioni, Marta Chiappetta, Augusto Faticoni, Daniela Marotta, Elena Mazzalai, Vanessa India Barletta, Shizuka Kibi, Vittoria Cammalleri, Barbara Dorelli, Monica Giffi, Roberta Noemi Pocino, Anna Paola Massetti, Caterina Fimiani, Ombretta Turriziani, Ferdinando Romano, Guido Antonelli, Alberto Deales, Claudio Maria Mastroianni, Fortunata Vasaturo and on behalf of Collaborative Group Sapienza
Additional contact information
Giuseppe La Torre: Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00185 Roma, Italy
Mattia Marte: Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00185 Roma, Italy
Carlo Maria Previte: Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00185 Roma, Italy
Lavinia Camilla Barone: Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00185 Roma, Italy
Filippo Picchioni: Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00185 Roma, Italy
Marta Chiappetta: Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00185 Roma, Italy
Augusto Faticoni: Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00185 Roma, Italy
Daniela Marotta: Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00185 Roma, Italy
Elena Mazzalai: Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00185 Roma, Italy
Vanessa India Barletta: Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00185 Roma, Italy
Shizuka Kibi: Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00185 Roma, Italy
Vittoria Cammalleri: Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00185 Roma, Italy
Barbara Dorelli: Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00185 Roma, Italy
Monica Giffi: Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00185 Roma, Italy
Roberta Noemi Pocino: Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00185 Roma, Italy
Anna Paola Massetti: Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00185 Roma, Italy
Caterina Fimiani: Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00185 Roma, Italy
Ombretta Turriziani: Laboratory of Virology, Department of Molecular Medicine, Sapienza University of Rome, 00185 Roma, Italy
Ferdinando Romano: Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00185 Roma, Italy
Guido Antonelli: Laboratory of Virology, Department of Molecular Medicine, Sapienza University of Rome, 00185 Roma, Italy
Alberto Deales: Health Direction, Teaching Hospital Policlinico Umberto I, 00161 Roma, Italy
Claudio Maria Mastroianni: Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00185 Roma, Italy
Fortunata Vasaturo: Clinica Medica Department of Internal Medicine and Medical Specialties, Sapienza University of Rome, 00185 Roma, Italy
on behalf of Collaborative Group Sapienza: Membership of the Collaborative Group Sapienza is provided in the Acknowledgments.

IJERPH, 2021, vol. 18, issue 18, 1-8

Abstract: The aim of this study is to assess the effect of contact time, contact distance and the use of personal protective equipment on the determination of SARS-CoV-2 infection in healthcare workers (HCWs). This study consists of an analysis of data gathered for safety reasons at the Sapienza Teaching Hospital Policlinico Umberto I in Rome through the surveillance system that was put into place after the worsening of the COVID-19 pandemic. The studied subjects consist of HCWs who were put under health surveillance, i.e., all employees who were in contact with subjects who were confirmed to have tested positive for SARS-CoV-2. The HCWs under surveillance were monitored for a period encompassing ten days after the date of contact, during which they undertook nasopharyngeal swab tests analysed through RT-PCR (RealStar® SARS-CoV-2 Altona Diagnostic–Germany). Descriptive and univariate analyses have been undertaken, considering the following as risk factors: (a) no personal protective equipment use (PPE); (b) Distance < 1 m between the positive and contact persons; (c) contact time > 15?. Finally, a Cox regression and an analysis of the level of synergism between factors, as specified by Rothman, were carried out. We analysed data from 1273 HCWs. Of these HCWs, 799 (62.8%) were females, with a sample average age of 47.8 years. Thirty-nine (3.1%) tested positive during surveillance. The overall incidence rate was 0.4 per 100 person-days. Time elapsed from the last exposure and a positive RT-PCR result ranged from 2 to 17 days (mean = 7, median = 6 days). In the univariate analysis, a distance <1 m and a contact time > 15? proved to be risk factors for the SARS-CoV-2 infection, with a hazard ratio (HR) of 2.62 (95% CI: 1.11–6.19) and 3.59 (95% IC: 1.57–8.21), respectively. The synergism analysis found the highest synergism between the “no PPE use” x “Contact time”. The synergy index S remains strongly positive also in the analysis of the factors “no PPE use” x “Distance” and “Time of contact” x “Distance”. This study confirms the absolute need to implement safety protocols during the pandemic and to use the correct PPE within health facilities in order to prevent SARS-CoV-2 infection. The analysis shows that among the factors considered (contact time and distance, no use of PPE), there is a strong synergistic effect.

Keywords: SARS-CoV-2; COVID-19; contact tracing; safety; synergism; personal protective equipment; distance; time of exposure (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2021
References: View complete reference list from CitEc
Citations: View citations in EconPapers (1)

Downloads: (external link)
https://www.mdpi.com/1660-4601/18/18/9456/pdf (application/pdf)
https://www.mdpi.com/1660-4601/18/18/9456/ (text/html)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:gam:jijerp:v:18:y:2021:i:18:p:9456-:d:631120

Access Statistics for this article

IJERPH is currently edited by Ms. Jenna Liu

More articles in IJERPH from MDPI
Bibliographic data for series maintained by MDPI Indexing Manager ().