## 4 Discussion  
During the COVID-19 pandemic, environmental surveillance was used as a complementary tool to clinical surveillance for SARS-CoV-2 infection. Since the pandemic began, the investigation of wastewater has played a crucial role in environmental surveillance through the application of wastewater-based epidemiology (WBE) [33; 34]. To support this type of investigation, surface sampling has been used to increase information on the presence of the virus even in indoor environments [7; 9; 14; 20; 22]. Access to the university, which is normally visited by a significant number of students and teachers during the period of academic activities, was limited during the COVID era [35] and, therefore, few studies were carried out for the detection of the presence of the virus in the university environment [3; 36]. The SCOOP project aimed to investigate the presence and viability of SARS-CoV-2 in the environment of the University of Bari Aldo Moro during the fifth wave of the pandemic, when face-to-face activities started without the restrictions imposed by the lockdown. To our knowledge, this is the first study carried out in a university setting during the fifth phase of the pandemic. Our results show a higher viral positivity rate (5.4%) than that reported by other authors [3; 36], perhaps because this study was conducted over a longer period (seven months) and included particularly crowded events (e.g., graduation sessions) without the imposition of restrictive measures. According to some authors [37], crowding may be a risk factor for the detection of SARS-CoV-2, so more control and prevention measures, including better ventilation and symptom screening, may reduce viral transmission in various settings [38]. The presence of the virus on surfaces was not viable, probably because the viral load was not sufficient to determine the in vitro infection, but the transit of infected individuals was documented. Indeed, there was a linear correlation between Ct values and the probability of isolating the virus in vitro. Previous studies have shown that at high Ct values (>35), no virus growth was observed [24; 39]. Whole genome sequencing allowed the characterization of SARS-CoV-2 in a single positive sample. This characterized strain belonged to the omicron BA.5 clade, one of the lineages circulating during the sampling period [40]. In the remaining samples, sequencing was not feasible due to low RNA genome copies or possible RNA degradation in the samples, as reported in other studies [19; 41]. Although sequencing success correlates with the presence of a sufficient amount of virus on the swab and the integrity of the viral genome, this study shows that surface control may reflect the trend of circulating lineages of SARS-CoV-2. Another interesting aspect of our study relates to the nature of the surfaces tested. The presence of SARS-CoV-2 RNA was detected on both plasticized and non plasticized wood but never on plastic and metal. Some authors have demonstrated viral viability under artificial conditions for up to one day on wood and for longer periods (3/4 days) on plastic [4]. Our study is consistent with regional epidemiological data on COVID-19 cases among university students ([[https://covid-19.iss.it](https://covid-19.iss.it)]([https://covid-19.iss.it](https://covid-19.iss.it)) (accessed on 22 October 2023) [30], which confirm an increase in positive swabs for SARS-CoV-2 in the spring-summer period. Several authors have studied meteorological factors that could influence the spread of the virus, but uncertainties remain on the influence of humidity, temperature, rainfall, and ultraviolet radiation. These uncertainties could be due to high-risk bias related to vaccination practices [42], underestimation of notified cases, asymptomatic patients, geographical differences in the virus variant [43], climate change, and other related factors [44]. Most systematic reviews [45; 46; 47] have shown that cool and dry conditions favor the transmission of SARS-CoV-2.