The effect of laboratory-verified smoking on SARS-CoV-2 infection: results from the Troina sero-epidemiological survey

Abstract

Previous research yielded conflicting results on the association between cigarette smoking and risk of SARS-CoV-2 infection. Since the prevalence of smoking is high globally, the study of its impact on COVID-19 pandemic may have considerable implications for public health. This study is the first to investigate the association between the SARS-CoV-2 antibody sero-positivity and biochemically verified smoking status, to refine current estimates on this association. SARS-CoV-2-specific IgG and serum cotinine levels (a well-known marker of tobacco exposure) were assessed in a large sero-epidemiological survey conducted in the town of Troina (Sicily, Italy). A propensity score matching was carried out to reduce the effect of possible factors on SARS-CoV-2 infection risk among study participants. Of the 1785 subjects included in our study, one-third was classified as current smokers, based on serum cotinine levels. The overall proportion of subjects with positive serology for SARS-CoV-2 IgG was 5.4%. The prevalence of SARS-CoV-2 antibody positivity and previous COVID-19 diagnosis were reduced in smokers. This reduced prevalence persisted after adjusting for possible confounders (such as sex, age, previous infection, chronic conditions, and risk group) at regression analyses, and the point estimates based on the PS-matched models resulted consistent with those for the unmatched population. This study found a lower proportion of positive SARS-CoV-2 serology among current smokers, using direct laboratory measures of tobacco exposure and thus avoiding possible bias associated with self-reported smoking status. Results may also serve as a reference for future clinical research on potential pharmaceutical role of nicotine or nicotinic-cholinergic agonists against COVID-19.

Higher Infection Risk among Health Care Workers and Lower Risk among Smokers Persistent across SARS-CoV-2 Waves—Longitudinal Results from the Population-Based TiKoCo Seroprevalence Study

“…The observed association of smoking with decreased seropositivity was strong, stable across timepoints and subgroups, persistent when adjusted for potential confounding factors, and underscored by a dose–response association. The observed association with odds ratios around 0.5 were similarly observed in previously published seroprevalence studies of different designs [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ]. Altogether, this supports a genuine relationship between smoking and lower seropositivity.…”

“…SARS-CoV-2 antibodies measured in serum of population-based studies’ participants provide insights into the proportion of individuals who have experienced infection. SARS-CoV-2 infection-mediated seroprevalence has been reported to be increased for medical personnel and decreased for smokers in numerous studies [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ], including two studies from Germany [ 11 , 12 ] as well as our baseline (BL) assessment of the Tirschenreuth Study (TiKoCo) [ 13 ]. With the exception of [ 12 ], these results were based on cross-sectional data collected shortly after the first pandemic wave (summer 2020) or in fall 2020.…”

Risk of Repeated Adverse Effects following Booster Dose of mRNA COVID-19 Vaccine: Results from the MOSAICO Study

“…The risks of repeated muscle pain, fever and nausea were significantly lower in tobacco smokers. The study of smoking in the COVID-19 era has caught research attention since very first epidemic weeks [ 37 , 38 , 39 , 40 ]. The negative correlation between smoking and humoral response to vaccines has been widely described [ 41 , 42 ], and the lower occurrence of AEFI in smokers suggests a potential ancillary effect of tobacco use on the impairment of adequate innate and adaptive immune responses that underpin AEFI occurrence and, as is likely, general COVID-19 vaccine responses, which also reflect the change in smokers’ risk of breakthrough infection compared with the same risk in the pre-vaccination era [ 8 , 39 ].…”

Factors associated with receipt of COVID-19 vaccination and SARS-CoV-2 seropositivity among healthcare workers in Albania (February 2021–June 2022): secondary analysis of a prospective cohort study

“…Alternatively, smokers may have avoided infection-prone settings due to awareness of their increased risk of severe disease. However, several studies have suggested that smoking is associated with overall reduced levels of IgA, IgG and IgM titers, and of IgG following SARS-CoV-2 infection or COVID-19 vaccination, 55 , 56 , 57 , 58 , 59 hence a lower seroprevalence among smokers could be an artefact.…”