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.

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.

Cardiac involvement in consecutive unselected hospitalized COVID-19 population: In-hospital evaluation and one-year follow-up.

BACKGROUND: Cardiovascular disease (CVD) can occur in COVID-19 and has impact on clinical course. Data on CVD prevalence in hospitalized COVID-19 patients and sequelae in survivors is limited. Aim of this prospective study carried out on consecutive unselected COVID-19 population, was to assess: 1) CVD occurrence among hospitalized COVID-19 patients, 2) persistence or new onset of CVD at one-month and one-year follow-up. METHODS: Over 30 days n = 152 COVID-19 patients underwent cardiovascular evaluation. Standard electrocardiogram (ECG), Troponin and echocardiography were integrated by further tests when indicated. Medical history, arterial blood gas, blood tests, chest computed tomography and treatment were recorded. CVD was defined as the occurrence of a new condition during the hospitalization for COVID-19. Survivors attended a one-month follow-up visit and a one-year telephone follow-up. RESULTS: Forty-two patients (28%) experienced a wide spectrum of CVD with acute myocarditis being the most frequent. Death occurred in 32 patients (21%) and more frequently in patients who developed CVD (p = 0.032). After adjustment for confounders, CVD was independently associated with death occurrence. At one-month follow-up visit, 7 patients (9%) presented persistent or delayed CVD. At one-year telephone follow-up, 57 patients (48%) reported persistent symptoms. CONCLUSION: Cardiovascular evaluation in COVID-19 patients is crucial since the occurrence of CVD in hospitalized COVID-19 patients is common (28%), requires specific treatment and increases the risk of in-hospital mortality. Persistence or delayed presentation of CVD at 1-month (9%) and persistent symptoms at 1-year follow-up (48%) suggest the need for monitoring COVID-19 survivors.

Detection of SARS-COV N2 Gene: Very low amounts of viral RNA or false positive?

BACKGROUND: The detection of a low amount of viral RNA is crucial to identify a SARS-CoV-2 positive individual harboring a low level of virus, especially during the convalescent period. However, the detection of one gene at high Cycle threshold (Ct) has to be interpreted with caution. In this study we address this specific issue and report our real-life experience. STUDY DESIGN: A total of 1639 nasopharyngeal swabs (NPS) were analyzed with Xpert® Xpress SARS-CoV-2. Positive samples showing high Ct values (Ct>35) were concentrated by centrifugation and re-tested with Cepheid or other methods (RealStar SARS-CoV2 RT-PCR, Altona Diagnostics; GeneFinder COVID-19 Plus RealAmp Kit, Elitech). RESULTS: 1599 (97.5%) negative samples, 36 (2.3%) positive samples and 4 (0.2%) presumptive positive samples were detected. In 17 out of 36 positive patients, very low viral RNA copies were suspected since positivity was detected at high Ct. We confirmed positivity for patients who showed both E and N genes detected and for patients with only N detected but with Ct <39. On the contrary, samples with only gene N detected with Ct values >39 were found negative. NPS taken 24 hours after the first collection confirmed the negativity of the 12 samples. Clinical data sustained these results since only 2 of these 12 patients showed COVID-19-like symptoms. CONCLUSIONS: These data support our consideration that detection of the N2 gene at high Ct needs to be interpreted with caution, suggesting that collaboration between virologists and clinicians is important for better understanding of results.