Antibody response of smokers to the COVID-19 vaccination: Evaluation based on cigarette dependence.

Smokers may have lower antibody titers after vaccination with a coronavirus disease 2019 (COVID-19) mRNA vaccine. However, to the best of our knowledge, no study has evaluated antibody titers after COVID-19 vaccination based on the level of smokers' cigarette dependence. In this study, we measured the level of serum anti-severe acute respiratory syndrome coronavirus 2 (anti-SARS-CoV-2) spike protein receptor-binding domain (S-RBD) immunoglobulin-G (IgG) by enzyme linked immunosorbent assay of 55 actively smoking Japanese social workers (firefighters, paramedics, and rescue workers) who had received two doses of the BNT162b2 vaccine. Further, we assessed their cigarette dependence using the Fagerstrom Test for Nicotine Dependence (FTND), measured their serum cotinine levels, and tested for their correlation with anti-RBD IgG levels. Serum anti-SARS-CoV-2 S-RBD protein IgG levels after BNT162b2 vaccination showed a significant negative correlation with FTND (ρ = -0.426, p = 0.001). In addition, serum cotinine level showed a significant positive correlation with FTND (ρ = 0.470, p = 0.000). However, no significant negative correlation was noted between serum cotinine and serum anti-SARS-CoV-2 S-RBD protein IgG levels (ρ = -0.156, p = 0.256). Our results suggest that smokers with strong cigarette dependence have inadequate anti-SARS-CoV-2 S-RBD protein IgG levels after COVID-19 mRNA vaccination.