Sero-epidemiological survey on the impact of smoking on SARS-CoV-2 infection and COVID-19 outcomes − The Troina Study Protocol (Preprint)

Background After the global spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), research has highlighted several aspects of the pandemic, focusing on clinical features and risk factors associated with infection and disease severity. However, emerging results on the role of smoking in SARS-CoV-2 infection susceptibility or Novel Coronavirus Disease 2019 (COVID-19) outcomes are conflicting, and their robustness remains uncertain. Objective In this context, this study aims at quantifying the proportion of SARS-CoV-2 antibody seroprevalence, studying the changes in antibody levels over time, and analyzing the association between the biochemically verified smoking status and SARS-CoV-2 infection. Methods The research design involves a 6-month prospective cohort study with serial sampling of the same individuals. Each participant will be surveyed about their demographics and COVID-19-related information, and blood sampling will be collected upon recruitment and at specified follow-up time points (namely, after 8 and 24 weeks). Blood samples will be screened for the presence of SARS-CoV-2 specific antibodies and serum cotinine, being the latter the principal metabolite of nicotine, which will be used to assess participants' smoking status. Results The study is ongoing. It aims to find a higher antibody prevalence in individuals at high-risk for viral exposure (i.e., healthcare personnel), and to refine current estimates on the association between smoking status and SARS-CoV-2/COVID-19. Conclusions The added value of this research is that the current smoking status of the population to be studied will be biochemically verified, in order to avoid the bias associated with self-reported smoking status. As such, the results from this survey may provide actionable metric to study the role of smoking in SARS-CoV-2 infection and COVID-19 outcomes, and therefore implement the most appropriate public health measures to control the pandemic. Results may also serve as a reference for future clinical research and the methodology could be exploited in public health sectors and policies.