Determination of soluble angiotensin-converting enzyme 2 in saliva samples and its association with nicotine.

INTRODUCTION: The Angiotensin-Converting Enzyme 2 (ACE2) is the main receptor of the SARS-CoV-2. There is contradictory evidence on how the exposure to nicotine may module the concentration of soluble ACE2 (sACE2). The aim of this study was to assess the association between nicotine and sACE2 concentrations in saliva samples. METHODS: Pooled analysis performed with data retrieved from two studies (n = 634 and n = 302). Geometric mean (GM) concentrations of sACE2, both total and relative to the total amount of protein in the sample, were compared according to sociodemographic variables and variables associated to nicotine. Multivariable linear regression models were fitted to explore the associations of sACE2 with nicotine adjusting for sex, age and body mass index. Spearman's rank-correlation coefficients were estimated between the concentrations of nicotine and cotinine, and pack-years, the concentration of relative sACE2 and the isoforms of sACE2. RESULTS: We observed a significant increase of 0.108‰ and 0.087 ng/µl in the relative and absolute salivary sACE2 GM concentrations, respectively, between the lowest and highest nicotine levels. Similar results were observed for cotinine. These associations did not change in the multivariable linear models. There was a low correlation of nicotine and cotinine concentration with the concentration of relative salivary sACE2 (rs = 0.153 and rs = 0.132, respectively), pack-years (rs = 0.222 and rs = 0.235, respectively) and with the concentration of isoform 40 KDa (rs = 0.193 and rs = 0.140, respectively). CONCLUSION: Salivary nicotine concentration seems to be limitedly associated with the concentration of sACE2.

Relationship between double COVID-19 vaccine uptake and trust in effectiveness and safety of vaccination in general in 23 Member states of the European Union: an ecological study.

INTRODUCTION: The aim of this study was to assess the relationship between double COVID-19 vaccine uptake and trust in effectiveness and safety of vaccination in general in 23 European Union (EU) countries. METHODS: Ecological study. Data was retrieved from the Flash Eurobarometer 494 and Our World in Data. We estimated Pearson's correlation coefficients and fitted multiple linear regression models. RESULTS: There is a negative linear correlation between the percentage of people doubly vaccinated and the percentage of low trust in vaccine effectiveness (r = -0.48, p-value = 0.021), and the percentage of low trust in vaccine safety (r = -0.43, p-value = 0.041). There is a negative adjusted relation between the percentage of low trust in vaccine safety and the percentage of people doubly vaccinated (aß% low trust in vaccinesafety:-0.25; 95% CI: -0.49,-0.01, p-value = 0.045). CONCLUSION: An increase in health literacy of people living in certain countries in the EU may be needed to boost COVID-19 vaccine uptake.