Case-Control Study on the Routes of Transmission of SARS-CoV-2 after the Third Pandemic Wave in Tuscany, Central Italy

Abstract

The emergence of hyper-transmissible SARS-CoV-2 variants that rapidly became prevalent throughout the world in 2022 made it clear that extensive vaccination campaigns cannot represent the sole measure to stop COVID-19. However, the effectiveness of control and mitigation strategies, such as the closure of non-essential businesses and services, is debated. To assess the individual behaviours mostly associated with SARS-CoV-2 infection, a questionnaire-based case-control study was carried out in Tuscany, Central Italy, from May to October 2021. At the testing sites, individuals were invited to answer an online questionnaire after being notified regarding the test result. The questionnaire collected information about test result, general characteristics of the respondents, and behaviours and places attended in the week prior to the test/symptoms onset. We analysed 440 questionnaires. Behavioural differences between positive and negative subjects were assessed through logistic regression models, adjusting for a fixed set of confounders. A ridge regression model was also specified. Attending nightclubs, open-air bars or restaurants and crowded clubs, outdoor sporting events, crowded public transportation, and working in healthcare were associated with an increased infection risk. A negative association with infection, besides face mask use, was observed for attending open-air shows and sporting events in indoor spaces, visiting and hosting friends, attending courses in indoor spaces, performing sport activities (both indoor and outdoor), attending private parties, religious ceremonies, libraries, and indoor restaurants. These results might suggest that during the study period people maintained a particularly responsible and prudent approach when engaging in everyday activities to avoid spreading the virus.

Keeping university open did not increase the risk of SARS-CoV-2 acquisition: A test negative case-control study among students

“…Conversely, social activities often considered highrisk, such as frequenting restaurants, bars or pubs, did not have an impact on the risk of infection in our sample, contrary to evidence in the published literature [5,[7][8][9]12]. More in line with the existing literature is the lack of an association with other social activities, such as shopping [4,5,[7][8][9]12], attending indoor sports activities [5,7,8,12], and using public transport [4,5,7]. Overall these data seem to indicate a minimal risk when visiting places that implement strict preventive measures such as mandatory use of face masks and physical distancing, reduction of maximum capacity, and regulation of access by means of the EU digital COVID certificate [4,8,12,15,17,19].…”

“…Visiting discos or clubs was associated with an increased risk of SARS-CoV-2 infection, consistent with a large body of evidence on the role of parties in the youth population [5,8,12,18,20,50] and the fact that in discos or clubs the recommended controls and preventive measures are more likely to be sidelined [51]. Conversely, social activities often considered highrisk, such as frequenting restaurants, bars or pubs, did not have an impact on the risk of infection in our sample, contrary to evidence in the published literature [5,[7][8][9]12].…”

“…Visiting discos or clubs was associated with an increased risk of SARS-CoV-2 infection, consistent with a large body of evidence on the role of parties in the youth population [5,8,12,18,20,50] and the fact that in discos or clubs the recommended controls and preventive measures are more likely to be sidelined [51]. Conversely, social activities often considered highrisk, such as frequenting restaurants, bars or pubs, did not have an impact on the risk of infection in our sample, contrary to evidence in the published literature [5,[7][8][9]12]. More in line with the existing literature is the lack of an association with other social activities, such as shopping [4,5,[7][8][9]12], attending indoor sports activities [5,7,8,12], and using public transport [4,5,7].…”

“…More in line with the existing literature is the lack of an association with other social activities, such as shopping [4,5,[7][8][9]12], attending indoor sports activities [5,7,8,12], and using public transport [4,5,7]. Overall these data seem to indicate a minimal risk when visiting places that implement strict preventive measures such as mandatory use of face masks and physical distancing, reduction of maximum capacity, and regulation of access by means of the EU digital COVID certificate [4,8,12,15,17,19].…”

“…In this context, the identification of risk factors for the transmission of SARS-CoV-2 infection is crucial to guide health policy decisions aimed at limiting virus transmission and, at the same time, preserving the normal activities of everyday life as far as possible [2,3]. However, few analytical epidemiological studies have been conducted worldwide to investigate the risk factors for SARS-CoV-2 acquisition [4][5][6][7][8][9][10][11][12][13], particularly in healthy individuals attending community settings and areas posing unique challenges for transmission control, such as schools [14][15][16] and higher education institutions (HEIs) [17][18][19][20].…”