The Role of Smoking and Nicotine in the Transmission and Pathogenesis of COVID-19

Liver injury in COVID-19: an insight into pathobiology and roles of risk factors

COVID-19 is a complex disease that can lead to fatal respiratory failure with extrapulmonary complications, either as a direct result of viral invasion in multiple organs or secondary to oxygen supply shortage. Liver is susceptible to many viral pathogens, and due to its versatile functions in the body, it is of great interest to determine how hepatocytes may interact with SARS-CoV-2 in COVID-19 patients. Liver injury is a major cause of death, and SARS-CoV-2 is suspected to contribute significantly to hepatopathy. Owing to the lack of knowledge in this field, further research is required to address these ambiguities. Therefore, we aimed to provide a comprehensive insight into host-virus interactions, underlying mechanisms, and associated risk factors by collecting results from epidemiological analyses and relevant laboratory experiments. Backed by an avalanche of recent studies, our findings support that liver injury is a sequela of severe COVID-19, and certain pre-existing liver conditions can also intensify the morbidity of SARS-CoV-2 infection in synergy. Notably, age, sex, lifestyle, dietary habits, coinfection, and particular drug regimens play a decisive role in the final outcome and prognosis as well. Taken together, our goal was to unravel these complexities concerning the development of novel diagnostic, prophylactic, and therapeutic approaches with a focus on prioritizing high-risk groups.

Risk profiles for smoke behavior in COVID-19: a classification and regression tree analysis approach

BACKGROUND

COVID-19 pandemic emerged worldwide at the end of 2019, causing a severe global public health threat, and smoking is closely related to COVID-19. Previous studies have reported changes in smoking behavior and influencing factors during the COVID-19 period, but none of them explored the main influencing factor and high-risk populations for smoking behavior during this period.

METHODS

We conducted a nationwide survey and obtained 21,916 valid data. Logistic regression was used to examine the relationships between each potential influencing factor (sociodemographic characteristics, perceived social support, depression, anxiety, and self-efficacy) and smoking outcomes. Then, variables related to smoking behavior were included based on the results of the multiple logistic regression, and the classification and regression tree (CART) method was used to determine the high-risk population for increased smoking behavior during COVID-19 and the most profound influencing factors on smoking increase. Finally, we used accuracy to evaluated the performance of the tree.

RESULTS

The strongest predictor of smoking behavior during the COVID-19 period is acceptance degree of passive smoking. The subgroup with a high acceptation degree of passive smoking, have no smokers smoked around, and a length of smoking of ≥ 30 years is identified as the highest smoking risk (34%). The accuracy of classification and regression tree is 87%.

CONCLUSION

The main influencing factor is acceptance degree of passive smoking. More knowledge about the harm of secondhand smoke should be promoted. For high-risk population who smoke, the "mask protection" effect during the COVID-19 pandemic should be fully utilized to encourage smoking cessation.

Nicotine: From Discovery to Biological Effects

Nicotine, the primary psychoactive agent in tobacco leaves, has led to the widespread use of tobacco, with over one billion smokers globally. This article provides a historical overview of tobacco and discusses tobacco dependence, as well as the biological effects induced by nicotine on mammalian cells. Nicotine induces various biological effects, such as neoangiogenesis, cell division, and proliferation, and it affects neural and non-neural cells through specific pathways downstream of nicotinic receptors (nAChRs). Specific effects mediated by α7 nAChRs are highlighted. Nicotine is highly addictive and hazardous. Public health initiatives should prioritize combating smoking and its associated risks. Understanding nicotine's complex biological effects is essential for comprehensive research and informed health policies. While potential links between nicotine and COVID-19 severity warrant further investigation, smoking remains a significant cause of morbidity and mortality globally. Effective public health strategies are vital to promote healthier lifestyles.

Substances of abuse and their effect on SAR-CoV-2 pathogenesis

Following the emergence of SARS-CoV-2, various reports suggest that there has been a significant increase in substance abuse due to social distancing and related issues. Several reports have suggested the impact of chronic substance use on individuals' physiological and psychological health. Therefore, there is a need to know the impact of SARS-CoV-2 on persons with substance use disorders. Individuals with substance use disorders are the most vulnerable groups and are at a high risk of SARS-CoV-2 infection due to their already existing health issues associated with substance use. This review discusses some of the molecular and systemic/organic effects chronic substance use such as alcohol, nicotine, marijuana (cannabis), opioids, methamphetamine, and cocaine have on SARS-CoV-2 infectivity and its potential cause for worsened disease outcomes in persons with substance use disorder. This will provide healthcare providers, public health policies, and researchers with the needed knowledge to address some of the many challenges faced during the Covid-19 pandemic to facilitate treatment strategies for persons with substance use disorders.

SARS-CoV-2 versus Influenza A Virus: Characteristics and Co-Treatments

For three years, the novel coronavirus disease 2019 (COVID-19) pandemic, caused by infection of the SARS-CoV-2 virus, has completely changed our lifestyles and prepared us to live with this novel pneumonia for years to come. Given that pre-existing flu is caused by the influenza A virus, we have begun unprecedently co-coping with two different respiratory diseases at the same time. Hence, we draw a comparison between SARS-CoV-2 and influenza A virus based on the general characteristics, especially the main variants’ history and the distribution of the two viruses. SARS-CoV-2 appeared to mutate more frequently and independently of locations than the influenza A virus. Furthermore, we reviewed present clinical trials on combined management against COVID-19 and influenza in order to explore better solutions against both at the same time.

Nicotine has no significant cytoprotective activity against SARS-CoV-2 infection

When coronavirus disease 2019 (COVID-19) became a pandemic, one of most important questions was whether people who smoke are at more risk of COVID-19 infection. A number of clinical data have been reported in the literature so far, but controversy exists in the collection and interpretation of the data. Particularly, there is a controversial hypothesis that nicotine might be able to prevent SARS-CoV-2 infection. In the present study, motivated by the reported controversial clinical data and the controversial hypothesis, we carried out cytotoxicity assays in Vero E6 cells to examine the potential cytoprotective activity of nicotine against SARS-CoV-2 infection and demonstrated for the first time that nicotine had no significant cytoprotective activity against SARS-CoV-2 infection in these cells.

E-cigarettes and youth: an unresolved Public Health concern

The use of electronic cigarettes (e-cigarette) and vaping devices started as a potential aid for cessation and reducing the harmful consequences of cigarette smoking, mainly in the adult population. Today e-cigarette use is highly increasing in vulnerable populations, especially young and pregnant women, due to the misconception of its harmless use.

Despite the growing acknowledgment in e-cigarette as a potential harmful device, and due to mixed information found concerning its beneficial aid for smokers, along with an insufficient clinical study done in human models, it is important to further evaluate the possible benefits and risks of non-combusting, vaping nicotine or non-nicotine delivery devices.

In this review we tried to summarize the latest updated information found in the literature, concentrating mainly in the variety of adverse effects of e-cigarette use and its contribution for recent and future health concerns.

Potential role of astrocyte angiotensin converting enzyme 2 in the neural transmission of COVID-19 and a neuroinflammatory state induced by smoking and vaping

Background

Knowledge of the entry receptors responsible for SARS-CoV-2 is key to understand the neural transmission and pathogenesis of COVID-19 characterized by a neuroinflammatory scenario. Understanding the brain distribution of angiotensin converting enzyme 2 (ACE2), the primary entry receptor for SARS-CoV-2, remains mixed. Smoking has been shown as a risk factor for COVID-19 severity and it is not clear how smoking exacerbates the neural pathogenesis in smokers.

Methods

Immunohistochemistry, real-time PCR and western blot assays were used to systemically examine the spatial-, cell type- and isoform-specific expression of ACE2 in mouse brain and primary cultured brain cells. Experimental smoking exposure was conducted to evaluate the effect of smoking on brain expression.

Results

We observed ubiquitous expression of ACE2 but uneven brain distribution, with high expression in the cerebral microvasculature, medulla oblongata, hypothalamus, subventricular zones, and meninges around medulla oblongata and hypothalamus. Co-staining with cell type-specific markers demonstrates ACE2 is primarily expressed in astrocytes around the microvasculature, medulla oblongata, hypothalamus, ventricular and subventricular zones of cerebral ventricles, and subependymal zones in rhinoceles and rostral migratory streams, radial glial cells in the lateral ventricular zones, tanycytes in the third ventricle, epithelial cells and stroma in the cerebral choroid plexus, as well as cerebral pericytes, but rarely detected in neurons and cerebral endothelial cells. ACE2 expression in astrocytes is further confirmed in primary cultured cells. Furthermore, isoform-specific analysis shows astrocyte ACE2 has the peptidase domain responsible for SARS-CoV-2 entry, indicating astrocytes are indeed vulnerable to SARS-CoV-2 infection. Finally, our data show experimental tobacco smoking and electronic nicotine vaping exposure increase proinflammatory and/or immunomodulatory cytokine IL-1a, IL-6 and IL-5 without significantly affecting ACE2 expression in the brain, suggesting smoking may pre-condition a neuroinflammatory state in the brain.

Conclusions

The present study demonstrates a spatial- and cell type-specific expression of ACE2 in the brain, which might help to understand the acute and lasting post-infection neuropsychological manifestations in COVID-19 patients. Our data highlights a potential role of astrocyte ACE2 in the neural transmission and pathogenesis of COVID-19. This also suggests a pre-conditioned neuroinflammatory and immunocompromised scenario might attribute to exacerbated COVID-19 severity in the smokers.

Structural evidence of the oxidation of iodide ion into hyper-reactive hypoiodite ion by mammalian heme lactoperoxidase

Lactoperoxidase (1.11.1.7, LPO) is a mammalian heme peroxidase found in the extracellular fluids of mammals including plasma, saliva, airway epithelial lining fluids, nasal lining fluid, milk, tears, gastric juices, and intestinal mucosa. To perform its innate immune action against invading microbes, LPO utilizes hydrogen peroxide (H₂ O₂ ) to convert thiocyanate (SCN^- ) and iodide (I^- ) ions into the oxidizing compounds hypothiocyanite (OSCN^- ) and hypoiodite (IO^- ). Previously determined structures of the complexes of LPO with SCN^- , OSCN^- , and I^- show that SCN^- and I^- occupy appropriate positions in the distal heme cavity as substrates while OSCN^- binds in the distal heme cavity as a product inhibitor. We report here the structure of the complex of LPO with IO^- as the first structural evidence of the conversion of iodide into hypoiodite by LPO. To obtain this complex, a solution of LPO was first incubated with H₂ O₂ , then mixed with ammonium iodide solution and the complex crystallized by the addition of PEG-3350, 20% (wt/vol). These crystals were used for X-ray intensity data collection and structure analysis. The structure determination revealed the presence of four hypoiodite ions in the substrate binding channel of LPO. In addition to these, six other hypoiodite ions were observed at different exterior sites. We surmise that the presence of hypoiodite ions in the distal heme cavity blocks the substrate binding site and inhibits catalysis. This was confirmed by activity experiments with the colorimetric substrate, ABTS (2,2'-azino-bis(3-ethylbenzthiazoline-sulfonic acid)), in the presence of hypoiodite and iodide ions.

Symptoms COVID 19 Positive Vapers Compared to COVID 19 Positive Non-vapers

Objectives:

The purpose of the present study was to assess and describe the severity of symptoms reported by Covid-19 positive patients who vaped (smoked e-cigarettes) when compared to those who did not vape or smoke at the time of the diagnosis of Covid-19.

Methods:

Patients from this study are from a well-characterized patient cohort collected at Mayo Clinic between March 1, 2020 and February 28, 2021; with confirmed COVID-19 diagnosis defined as a positive result on reverse-transcriptase–polymerase-chain-reaction (RT-PCR) assays from nasopharyngeal swab specimens. Among the 1734 eligible patients, 289 patients reported current vaping. The cohort of vapers (N = 289) was age and gender matched to 1445 covid-19 positive patients who did not vape. The data analyzed included: date of birth, gender, ethnicity, race, marital status, as well as lifestyle history such as vaping and smoking and reported covid-19 symptoms experienced.

Results:

A logistic regression analysis was performed separately for each symptom using generalized estimating equations (GEE) with robust variance estimates in order to account for the 1:5 age, sex, and race matched set study design. Patients who vaped and developed Covid-19 infection were more likely to have chest pain or tightness (16% vs 10%, vapers vs non vapers, P = .005), chills (25% vs 19%, vapers vs non vapers, P = .0016), myalgia (39% vs 32%, vapers vs non vapers, P = .004), headaches (49% vs 41% vapers vs non vapers, P = .026), anosmia/dysgeusia (37% vs 30%, vapers vs non vapers, P = .009), nausea/vomiting/abdominal pain (16% vs 10%, vapers vs non vapers, P = .003), diarrhea (16% vs 10%, vapers vs non vapers, P = .004), and non-severe light-headedness (16% vs 9%, vapers vs non vapers, P < .001).

Conclusion:

Vapers experience higher frequency of covid-19 related symptoms when compared with age and gender matched non-vapers. Further work should examine the impact vaping has on post-covid symptom experience.

Clinical manifestations and socio-demographic status of COVID-19 patients during the second-wave of pandemic: A Bangladeshi experience

BACKGROUND

Bangladesh is a densely populated country with a substandard healthcare system and a mediocre economic framework. Due to the enormous number of people who have been unaware until now, the development of COVID-19's second-wave infection has become a severe threat. The present investigation aimed to characterize the clinical and socio-demographic characteristics of COVID-19 in Bangladesh.

METHODS

A cross-sectional analysis was carried out from all the other COVID-19 patients and confirmed by RT-PCR undergoing a specialized COVID-19 hospital. From March 1 to April 15, 2021, a total of 1326 samples were collected. Samples were only obtained from non-critical COVID-19 patients as critically ill patients required emergency intensive care medications. Then, from April 17 to May 03, 2021, SARS-CoV-2 infection and clinical assessment was performed based on interim guidelines from the WHO. The diagnosis was conducted through RT-PCR. Later, identifying the symptomatic and asymptomatic patient based on checking the Clinical Observation Form (COF). The patients filled the COF form. Finally, statistical analyses were done using the SPSS 20 statistical program.

RESULTS

In this investigation, a total of 326 patients were diagnosed as COVID-19 positive. Among them, approximately 19.02% (n = 62) were asymptomatic, and 80.98% (n = 264) were symptomatic. Here, the finding shows that the occurrence of this infection was varied depending on age, sex, residence, occupation, smoking habit, comorbidities, etc. However, Males (60.12%) were more affected than females (39.88%), and, surprisingly, this pandemic infected both urban and rural residents almost equally (urban = 50.92%; rural = 49.08%). Approximately 19% of the asymptomatic and 62% of symptomatic cases had at least one comorbid disorder. Interestingly, an unexpected result was exhibited in the case of smokers, where non-smokers were more affected than smokers. The study indicates community transmission of COVID 19, where people were highly infected at their occupations (35.58%), at houses (23.93%) and by traveling (12.88%). Noteworthy, according to this report, a large number (19.33%) of individuals did not know exactly how they were contaminated with SARS-CoV-2. Patients were most commonly treated by an antibiotic 95.09%, followed in second by corticosteroid 46.01%. Anti-viral drugs, remdesivir, and oxygenation are also needed for other patients. Among those, who were being treated, approximately 69.33% were isolated at home, 27.91% were being treated at dedicated COVID-19 hospitals. Finally, 96.63% were discharged without complications, and 0.03% has died.

CONCLUSION

This investigation concludes that males became more infected than females. Interestingly, both urban and rural people became nearly equally infected. It noticed community transmission of SARS-CoV-2, where people were highly infected at their workplaces. A higher rate of silent transmission indicates that more caution is needed to identify asymptomatic patients. Most of the infected people were isolated at home whereas nearly one-fourth were treated at hospitals. Clinically, antibiotics were the most widely used treatment. However, the majority of the patients were discharged without complications. The current investigation would be helpful to understand the clinical manifestations and socio-demographic situations during the second wave of the COVID-19 pandemic in Bangladesh.

High COVID-19 morbidity and mortality risk among smoked drug users in Brazil

ABSTRACT

In much of the West, including Brazil, drug use has increased since social distancing began in response to the pandemic. Use of smoked and modified drugs, and their impacts on health, may contribute to aggravate the effects of the pandemic. However, studies on the relationship between use of smoked drugs and the new coronavirus are still scarce and have not received enough attention in global health recommendations. This paper aims to briefly review the relationship between use of smoked drugs and acute respiratory syndrome coronavirus 2 [SARS-CoV-2]. Recent studies also suggest that drug consumption increases the risk of contamination by SARS-CoV-2 and leads to worse prognosis, particularly consumption of drugs that affect lung function. Use of smoked drugs, especially tobacco, is strongly associated with lung diseases that are risk factors for contamination by SARS-CoV-2. It is essential to develop strategies based on specific characteristics of drug users and for mental health professionals to be included in strategic teams. It is also necessary to invest in information campaigns regarding risks and prevention of harm caused by smoked drugs as well as to design strategies that facilitate access to psychosocial treatment during the pandemic.

Modeling Aerial Transmission of Pathogens (Including the SARS-CoV-2 Virus) through Aerosol Emissions from E-Cigarettes

We examine the plausibility of aerial transmission of pathogens (including the SARS-CoV-2 virus) through respiratory droplets that might be carried by exhaled e-cigarette aerosol (ECA). Given the lack of empiric evidence on this phenomenon, we consider available evidence on cigarette smoking and respiratory droplet emission from mouth breathing through a mouthpiece as convenient proxies to infer the capacity of vaping to transport pathogens in respiratory droplets. Since both exhaled droplets and ECA droplets are within the Stokes regime, the ECA flow acts effectively as a visual tracer of the expiratory flow. To infer quantitatively the direct exposure distance, we consider a model that approximates exhaled ECA flow as an axially symmetric intermittent steady starting jet evolving into an unstable puff, an evolution that we corroborate by comparison with photographs and videos of actual vapers. On the grounds of all this theoretical modeling, we estimate for low-intensity vaping (practiced by 80–90% of vapers) the emission of 6–210 (median 39.9, median deviation 67.3) respiratory submicron droplets per puff and a horizontal distance spread of 1–2 m, with intense vaping possibly emitting up to 1000 droplets per puff in the submicron range with a distance spread over 2 m. The optical visibility of the ECA flow has important safety implications, as bystanders become instinctively aware of the scope and distance of possible direct contagion through the vaping jet.

A cross-section observational study on the seroprevalence of antibodies to COVID-19 in patients receiving opiate agonist treatment

Introduction

The HSE National Drug Treatment Centre is an inner city drug treatment centre in Dublin which provides opiate agonist treatment (OAT) to approximately 565 patients, many of whom have complex care needs.

Objective

This study was conducted to determine seropositivity to the COVID-19 virus in patients attending NDTC, and to establish if patients tested had any clinical symptoms of this disease since March 2020.

Method

All patients attending for OAT were invited to participate and 103/565 patients agreed. The patients were tested for the presence of serum antibodies to COVID-19 in a single sample collected over a 4-month period (July–October 2020). A questionnaire was administered at the same time as sample taking.

Results

Results showed that the majority of patient samples (100; 97%) tested were negative for the presence of antibodies to COVID-19. There were only two confirmed positive results (1.9%) and one equivocal result (1%). None of the approximately 565 attendees at the HSE NDTC presented with serious illness indicative of COVID-19 throughout the three waves of the pandemic, nor were any deaths due to COVID-19 reported.

Conclusion

These findings indicate (a) possible low level of exposure to COVID-19 among this patient cohort or (b) that those patients who have been exposed have not developed or maintained detectable antibody levels, nor developed symptoms of the disease. Public health measures could explain the low level of COVID-19 in this cohort. The findings are also consistent with the possibility of a protective effect of OAT medications on development of the disease.

Lower Gene Expression of Angiotensin Converting Enzyme 2 Receptor in Lung Tissues of Smokers with COVID-19 Pneumonia

Angiotensin-converting enzyme 2 (ACE-2) is the main cell entry receptor for severe acute respiratory syndrome-Coronavirus-2 (SARS-CoV-2), thus playing a critical role in causing Coronavirus disease 2019 (COVID-19). The role of smoking habit in the susceptibility to infection is still controversial. In this study we correlated lung ACE-2 gene expression with several clinical/pathological data to explore susceptibility to infection. This is a retrospective observational study on 29 consecutive COVID-19 autopsies. SARS-CoV-2 genome and ACE-2 mRNA expression were evaluated by real-time polymerase chain reaction in lung tissue samples and correlated with several data with focus on smoking habit. Smoking was less frequent in high than low ACE-2 expressors (p = 0.014). A Bayesian regression also including age, gender, hypertension, and virus quantity confirmed that smoking was the most probable risk factor associated with low ACE-2 expression in the model. A direct relation was found between viral quantity and ACE-2 expression (p = 0.028). Finally, high ACE-2 expressors more frequently showed a prevalent pattern of vascular injury than low expressors (p = 0.049). In conclusion, ACE-2 levels were decreased in the lung tissue of smokers with severe COVID-19 pneumonia. These results point out complex biological interactions between SARS-CoV-2 and ACE-2 particularly concerning the aspect of smoking habit and need larger prospective case series and translational studies.

Electronic Cigarettes and Vaping-Associated Lung Injury (EVALI): A Rural Appalachian Experience

Background: Electronic cigarette use has increased dramatically since their introduction in 2007. Respiratory complications, particularly lipoid pneumonia, have been reported as early as 2012. An outbreak of pulmonary injury in 2019 has been reported in patients using vaping products.Research Question: To describe a rural Appalachian tertiary center's experience of EVALI and to identify novel mechanisms of pulmonary injury patterns.Study Design and Methods: We present a consecutive case series of 17 patients admitted to our rural, academic, tertiary care institution with EVALI from August 2019 to March 2020. Demographics, baseline characteristics, co-morbidities, vaping behavior, and hospital course were recorded. Broncho-alveolar lavage specimens were assessed for lipid-laden macrophages and hemosiderin-laden macrophages with stains for Oil-Red-O (n = 15) and Prussian Blue (n = 14) respectively.The patient volunteered e-liquid materials (n = 6), and vapors were analyzed using a proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS) to describe the chemical profile. Post-discharge interviews were conducted.Results: The most common CT finding was bilateral ground-glass opacities with a predilection for lower lung zones. The most frequent pulmonary injury pattern was lipoid pneumonia. The majority of EVALI patients were critically ill requiring ventilation or ECMO. The most severely ill patients were noted to be positive for iron stains in macrophages and showed higher volatile organic compound (VOC) levels in chemical analysis.Interpretation: Based on our experience, EVALI in rural Appalachia presented with relatively severe respiratory failure. Worse outcomes appear to be correlated to high levels of VOCs, iron deposition in lungs, and concomitant infection.

Heterogeneity in COVID-19 patient volume, characteristics and outcomes across US Department of Veterans Affairs facilities: an observational cohort study

OBJECTIVE

Studies describe COVID-19 patient characteristics and outcomes across populations, but reports of variation across healthcare facilities are lacking. The objectives were to examine differences in COVID-19 patient volume and mortality across facilities, and understand whether facility variation in mortality was due primarily to differences in patient versus facility characteristics.

DESIGN

Observational cohort study with multilevel mixed effects logistic regression modelling.

SETTING

The Veterans Health Administration (VA) is the largest healthcare system in the USA.

PARTICIPANTS

Patients with COVID-19.

MAIN OUTCOME

All-cause mortality within 45 days after COVID-19 testing (March-May, follow-up through 16 July 2020).

RESULTS

Among 13 510 patients with COVID-19, 3942 (29.2%) were admitted (2266/3942 (57.5%) ward; 1676/3942 (42.5%) intensive care unit (ICU)) and 679/3942 (17.2%) received mechanical ventilation. Marked heterogeneity was observed across facilities in median age (range: 34.3-83.9 years; facility mean: 64.7, SD 7.2 years); patient volume (range: 1-737 at 160 facilities; facility median: 48.5, IQR 14-105.5); hospital admissions (range: 1-286 at 133 facilities; facility median: 11, IQR 1-26.5); ICU caseload (range: 1-85 at 115 facilities; facility median: 4, IQR 0-12); and mechanical ventilation (range: 1-53 at 90 facilities; facility median: 1, IQR 0-5). Heterogeneity was also observed in facility mortality for all patients with COVID-19 (range: 0%-29.7%; facility median: 8.9%, IQR 2.4%-13.7%); inpatients (range: 0%-100%; facility median: 18.0%, IQR 5.6%-28.6%); ICU patients (range: 0%-100%; facility median: 28.6%, IQR 14.3%-50.0%); and mechanical ventilator patients (range: 0%-100%; facility median: 52.7%, IQR 33.3%-80.6%). The majority of variation in facility mortality was attributable to differences in patient characteristics (eg, age).

CONCLUSIONS

Marked heterogeneity in COVID-19 patient volume, characteristics and mortality were observed across VA facilities nationwide. Differences in patient characteristics accounted for the majority of explained variation in mortality across sites. Variation in unadjusted COVID-19 mortality across facilities or nations should be considered with caution.

Aerial Transmission of the SARS-CoV-2 Virus through Environmental E-Cigarette Aerosols: Implications for Public Policies

We discuss the implications of possible contagion of COVID-19 through e-cigarette aerosol (ECA) for prevention and mitigation strategies during the current pandemic. This is a relevant issue when millions of vapers (and smokers) must remain under indoor confinement and/or share public outdoor spaces with non-users. The fact that the respiratory flow associated with vaping is visible (as opposed to other respiratory activities) clearly delineates a safety distance of 1-2 m along the exhaled jet to prevent direct exposure. Vaping is a relatively infrequent and intermittent respiratory activity for which we infer a mean emission rate of 79.82 droplets per puff (6-200, standard deviation 74.66) comparable to mouth breathing, it adds into shared indoor spaces (home and restaurant scenarios) a 1% extra risk of indirect COVID-19 contagion with respect to a "control case" of existing unavoidable risk from continuous breathing. As a comparative reference, this added relative risk increases to 44-176% for speaking 6-24 min per hour and 260% for coughing every 2 min. Mechanical ventilation decreases absolute emission levels but keeps the same relative risks. As long as direct exposure to the visible exhaled jet is avoided, wearing of face masks effectively protects bystanders and keeps risk estimates very low. As a consequence, protection from possible COVID-19 contagion through vaping emissions does not require extra interventions besides the standard recommendations to the general population: keeping a social separation distance of 2 m and wearing of face masks.

Young Canadian e-Cigarette Users and the COVID-19 Pandemic: Examining Vaping Behaviors by Pandemic Onset and Gender

The aim of this study was to test how youth and young adult e-cigarette users responded to the COVID-19 pandemic. The 2020 Youth and Young Adult Vaping Survey (N = 1,308) included 540 (44.7%) participants that reported differences in their vaping behaviors since the onset of the pandemic. Gender was the only relevant covariate that yielded a significant effect and/or interaction through a multivariate test. A two-way multivariate analysis of variance was used to test the effect of pandemic onset (pre- vs. during-pandemic), gender (males vs. females), and their interaction on vaping behaviors (days of vaping per week, episodes of vaping per day, and puffs per vaping episode). Respondents reported fewer days of vaping per week, episodes of vaping per day, and puffs per vaping episode during-pandemic than pre-pandemic [F_(3,533) = 52.81, p < 0.001, ηp2 = 0.229]. The multivariate effect of gender on the three vaping outcomes was not statistically significant [F_{(3, 533)} = 2.14, p = 0.095, ηp2 = 0.012], though the interaction between pandemic onset and gender was [F_{(3, 533)} = 2.86, p = 0.036, ηp2 = 0.016]. Males reported fewer episodes of vaping per day [t₍₂₆₂₎ = 7.40, p < 0.001, 95% CI: 5.19–8.97] and puffs per vaping episode [t₍₂₆₃₎ = 3.23, p = 0.001, 95% CI:0.292–1.20] during-pandemic than pre-pandemic. Females reported fewer vaping episodes per day during-pandemic than pre-pandemic [t₍₂₇₃₎ = 5.14, p < 0.001, 95% CI: 2.76–6.18]. Further, females reported more frequent puffs per vaping episode in comparison to males during-pandemic [t₍₅₃₈₎ = −2.38, p = 0.017, 95% CI: −2.09–0.200]. The COVID-19 pandemic presents an opportunity to reduce vaping through health promotion messaging. Since females take more puffs per vaping episode overall, they may benefit the most from greater vaping cessation supports.

Nicotine Changes Airway Epithelial Phenotype and May Increase the SARS-COV-2 Infection Severity

(1) Background: Nicotine is implicated in the SARS-COV-2 infection through activation of the α7-nAChR and over-expression of ACE2. Our objective was to clarify the role of nicotine in SARS-CoV-2 infection exploring its molecular and cellular activity. (2) Methods: HBEpC or si-mRNA-α7-HBEpC were treated for 1 h, 48 h or continuously with 10-7 M nicotine, a concentration mimicking human exposure to a cigarette. Cell viability and proliferation were evaluated by trypan blue dye exclusion and cell counting, migration by cell migration assay, senescence by SA-β-Gal activity, and anchorage-independent growth by cloning in soft agar. Expression of Ki67, p53/phospho-p53, VEGF, EGFR/pEGFR, phospho-p38, intracellular Ca2+, ATP and EMT were evaluated by ELISA and/or Western blotting. (3) Results: nicotine induced through α7-nAChR (i) increase in cell viability, (ii) cell proliferation, (iii) Ki67 over-expression, (iv) phospho-p38 up-regulation, (v) EGFR/pEGFR over-expression, (vi) increase in basal Ca2+ concentration, (vii) reduction of ATP production, (viii) decreased level of p53/phospho-p53, (ix) delayed senescence, (x) VEGF increase, (xi) EMT and consequent (xii) enhanced migration, and (xiii) ability to grow independently of the substrate. (4) Conclusions: Based on our results and on evidence showing that nicotine potentiates viral infection, it is likely that nicotine is involved in SARS-CoV-2 infection and severity.