Smoking and snus use among youth: A longitudinal analysis of risk factors and socioeconomic profile.

BACKGROUND: Norwegian youth smoking has, to a larger extent than snus use, been associated with lower socioeconomic strata, and research has pointed at ideas in the youth population about the popularity and normality of snus use that are not found for smoking. The objective of this study was to investigate the association between socioeconomic status and other risk factors with snus use and smoking among people in their late teens. METHODS: Based on data from the longitudinal MyLife school survey, collected in five yearly waves between 2017 and 2021 (N = 1830, age 16.8-20.6 years in 2021, 64% girls), logistic regressions were performed with monthly snus use and smoking as dependents, and parents' education, psychological characteristics and earlier smoking or snus use as independent variables. RESULTS: High socioeconomic status (parents' education) was associated with less smoking and snus use also after controlling for psychological characteristics and earlier smoking and snus use. Higher age increased the risk of snus use and reduced the risk of smoking. CONCLUSIONS: Youth snus use and smoking are associated with lower socioeconomic background. This supports the idea that snus use may have lost some of its position as a mainstream activity among youth.

If there had been no snus in Sweden: the impact of snus on mortality attributable to smoking.

In Sweden, there has been a massive transition from cigarette smoking to snus, the Swedish kind of low-toxicity oral tobacco. This product poses very little health risk compared to cigarettes, as illustrated by the fact that males in Sweden have Europe's lowest level of mortality attributable to smoking. The current investigation estimates how high the smoking-attributable mortality in Sweden would have been if there had been no snus in Sweden. It is made up by comparisons between observed Swedish data and two scenarios without snus: a group of comparable countries, and, a hypothetical Sweden with no snus use. Both comparisons suggest that around 3000 lives per year have been saved by the use of snus in Sweden.

A systematic review of cancer risk among users of smokeless tobacco (Swedish snus) exclusively, compared with no use of tobacco.

The main objective of this systematic review was to assess cancer risk, and mortality after cancer diagnosis, for exclusive users of Swedish snus, compared with non-users of tobacco. We followed international standards for systematic reviews and graded our confidence in the risk estimates using the GRADE approach. Our search gave 2450 articles, of which 67 were assessed in full text against our inclusion criteria. Of these, 14 cohort-studies and one case-control study were included in the review. The studies investigated risk of cancer in the oral cavity or oropharynx (3 studies), esophagus (1 study), stomach (1 study), pancreas (2 studies), colorectum (2 studies), anus (1 study) and lung (1 study), as well as malignant lymphoma (1 study), leukemia and multiple myeloma (1 study), melanoma (1 study), any cancer (1 study) and mortality after cancer diagnosis (4 studies). Cancer risk could only be evaluated in men as there was a general lack of data for women. All included studies were evaluated to have a moderate risk of bias, mostly related to validity of exposure information. An increased risk of cancer of the esophagus, pancreas, stomach and rectum as well as an association between use of snus and increased mortality after a cancer diagnosis was reported. Our confidence in the various risk estimates varied from moderate through low to very low.

Prevalence and persistence of Neisseria meningitidis carriage in Swedish university students.

The bacterium Neisseria meningitidis causes life-threatening disease worldwide, typically with a clinical presentation of sepsis or meningitis, but can be carried asymptomatically as part of the normal human oropharyngeal microbiota. The aim of this study was to examine N. meningitidis carriage with regard to prevalence, risk factors for carriage, distribution of meningococcal lineages and persistence of meningococcal carriage. Throat samples and data from a self-reported questionnaire were obtained from 2744 university students (median age: 23 years) at a university in Sweden on four occasions during a 12-month period. Meningococcal isolates were characterised using whole-genome sequencing. The carriage rate among the students was 9.1% (319/3488; 95% CI 8.2-10.1). Factors associated with higher carriage rate were age ≤22 years, previous tonsillectomy, cigarette smoking, drinking alcohol and attending parties, pubs and clubs. Female gender and sharing a household with children aged 0-9 years were associated with lower carriage. The most frequent genogroups were capsule null locus (cnl), group B and group Y and the most commonly identified clonal complexes (cc) were cc198 and cc23. Persistent carriage with the same meningococcal strain for 12 months was observed in two students. Follow-up times exceeding 12 months are recommended for future studies investigating long-term carriage of N. meningitidis.

Association between snus use and lipid status in Swedish men.

Snus is a common tobacco product in Sweden, but the cardiovascular risk profile for snus users is less known than for cigarette smokers. We examined the association of snus use with lipid status, particularly in comparison to non-tobacco use and cigarette smoking, using data from 5930 men in the Northern Sweden MONICA study. Tobacco use was self-reported in 1986 to 2014 (24.4% used snus) and blood samples were collected at the same time. Harmonized analyses on non-high-density lipoprotein (non-HDL) cholesterol, HDL cholesterol, and triglycerides were conducted in 2016 to 2018. Three hundred eighty-one snus users had also been examined more than once, allowing us to study the effect of discontinued use (achieved by 21.0%). In multivariable linear regression models, snus use was associated with higher HDL cholesterol and triglyceride concentrations compared to non-tobacco use (p values ≤ 0.04), and it was associated with higher HDL cholesterol concentrations and lower triglyceride concentrations compared to cigarette smoking (p values ≤ 0.02). Snus use was not associated with non-HDL cholesterol concentrations, irrespective of the comparison group (p values ≥ 0.07). There was no indication that higher intensity of snus use led to a worse lipid profile, given that high-consumers had higher HDL cholesterol concentrations than low-consumers (p value = 0.02), or that discontinuation of snus use led to a better lipid profile, given that continued users had lower triglyceride concentrations than discontinued users (p value = 0.03). Further studies are needed to confirm or refute our findings.

Factors associated with initiation and use of snus among adolescents.

AIM: We investigated factors associated with the initiation and continuation of snus use in adolescents in Norway. The associations with adolescents' own educational plans, the parents' educational level(s) and tobacco habits were estimated. METHODS: In this cross-sectional questionnaire-based study, 1465 patients aged 18-20 years participated. The questionnaire was administered at regular dental examinations in the public dental health service. To assess the association between individual factors and the initiation of tobacco habits, a generalised structural equation model with random effects at the clinic level was used. Binary responses were modelled using multilevel binary logistic regression, while the number of snus boxes used per month was modelled using a multilevel Poisson regression model. RESULTS: Of current (daily and occasional) tobacco users, 85% were snus users, including dual users of both snus and cigarettes. The median age of snus initiation was 16 years. Both parental snus use and smoking were associated with an increased risk of snus initiation, snus use and a higher amount of use. An increased risk of using snus was associated with male gender and with no educational plans or planning for further vocational education. The amount of snus used was higher among current snus users with a prior smoking history and among those planning for further vocational education. CONCLUSIONS: These findings may aid in developing and targeting tobacco prevention strategies aimed at young people. Tobacco prevention measures should start at the elementary school level. The strong association with parental tobacco habits underlines the importance of parents' influence on their children's tobacco use.

Current tobacco use and SARS-CoV-2 infection in two Norwegian population-based cohorts.

BACKGROUND: Clear evidence of an increased risk for SARS-CoV-2 infection among smokers has not been established. We aimed to investigate associations between cigarette smoking or use of snus (snuff) and other nicotine-containing products and a positive SARS-CoV-2 test, taking test behavior into account. METHODS: Current tobacco use and testing behavior during the pandemic were recorded by adult participants from the Norwegian Mother, Father and Child Cohort Study and The Norwegian Influenza Pregnancy Cohort. SARS-CoV-2 infection status was obtained from The Norwegian Surveillance System for Communicable Diseases (MSIS) in May 2021 (n = 78,860) and antibody measurements (n = 5581). We used logistic regression models stratified by gender and adjusted for age, education, region, number of household members, and work situation. RESULTS: Snus use was more common among men (26%) than women (9%) and more prevalent than cigarette smoking. We found no clear associations between cigarette smoking or snus and a COVID-19 diagnosis among men. Associations among women were conflicting, indicating that cigarette smoke was negatively associated with a diagnosis (OR 0.51, 95% CI 0.35, 0.75), while no association was found for snus use (OR 1.07, 95% CI 0.86, 1.34). Compared with non-users of tobacco, both cigarette smokers and snus users had increased odds of being tested for SARS-CoV-2. CONCLUSIONS: Cigarette smoking, but not snus use, was negatively associated with SARS-CoV-2 infection in women. The lack of an association between snus use and SARS-CoV-2 infection in this population with prevalent snus use does not support the hypothesis of a protective effect of nicotine.

Oral lesions associated with daily use of snus, a moist smokeless tobacco product. A cross-sectional study among Norwegian adolescents.

OBJECTIVE: Use of snus, a moist, smokeless tobacco product, may lead to local changes in the oral mucous membrane in the area where the snus is placed. It can also cause irreversible gingival retraction. This cross-sectional study aimed to investigate the relationship between use of snus, oral mucosal lesions (snus induced lesions) and gingival retractions among adolescents in Norway. MATERIAL AND METHODS: All 18-20 years olds visiting public dental health clinics in the south-eastern region of Norway between October 2015 and December 2016 were invited to participate. All participants (n = 1363) filled in an electronic questionnaire before a clinical examination. Of these, 216 used snus daily. RESULTS: Snus induced lesions were observed in 79.2% of daily snus using participants. In adjusted regression analyses, the odds of having a more severe lesion as opposed to a less severe lesion were 1.12 times greater for each additional box of snus used in a month (p < .01). Women were 46% less likely to have a severe lesion than men (p = .03). Gingival retractions were observed in 18.4% of the participants. The odds for dental retraction were significantly higher by 34% for each year of snus use. CONCLUSIONS: Most of the adolescents using snus had snus induced lesions, whereas approximately one-fifth had gingival retractions. The severity of the lesion and gingival retraction increased with the amount of snus boxes used and the duration of the snus use, respectively.

Assessment of the exposure to polycyclic aromatic hydrocarbons in users of various tobacco/nicotine products by suitable urinary biomarkers.

Polycyclic aromatic hydrocarbons (PAHs) occur naturally (bitumen and oils) and are formed during all incomplete combustions of organic materials. PAH exposure sources are manifold and include specific workplaces, ambient air, various foodstuffs, tobacco smoke and some medications. At least four members of this class of chemicals have been classified as proven or probable human carcinogens. Assessment of the exposure to PAHs with suitable methods is of importance, particularly in users of new-generation tobacco/nicotine products, which are intended to replace combustible cigarettes (CCs), a major source of non-occupational exposure to PAHs. In a clinical study comprising a period of 74 h under confinement, we investigated the exposure to naphthalene (Nap), fluorene (Flu), phenanthrene (Phe), pyrene (Pyr) and benzo[a]pyrene (BaP) by measuring urinary monohydroxy-PAH (OH-PAH) derived from these parent compounds in habitual users of CCs, electronic cigarettes (ECs), heated tobacco products (HTPs), oral tobacco (OT), and nicotine replacement therapy products (NRTs). Non-users (NU) of any tobacco/nicotine products served as (negative) control group. Smokers exhibited the highest levels for all PAH biomarkers measured, almost all of which were significantly different from the NU and user groups of all other products investigated. CC smokers were the only group which showed a significant relationship between almost all PAH biomarkers and dose markers such as daily consumption, urinary nicotine equivalents (Nequ) and plasma cotinine (CotP). The ratios in urinary OH-PAH between CC and all other groups were dependent on the biomarker and range from < 2 to > 10. These ratios could at least partly be explained by the enzymes involved, their region-selectivity and inducibility by smoking. In conclusion, cigarette smokers (CC) were the only group, which showed product use dependent exposure to PAHs, whereas users of EC, HTP, NRT and OT were not distinguishable from NU of any tobacco/nicotine products.

Smoking cessation aids and strategies: a population-based survey of former and current smokers in Norway.

BACKGROUND: In Norway, tobacco consumption is equally divided between combustible (cigarettes) and non-combustible (snus) tobacco. In the process of quitting, people who smoke can choose between several smoking cessation aids and strategies based on what is available on the market or what are recommended as cessation aids. A quit attempt may be planned or unplanned and consist of a gradual decline in consumption or an abrupt quitting. This study explores smoking cessation aids and strategies used at the latest quit attempt among people who have ever smoked. How prevalent is the use of various cessation aids and strategies, and do they correlate with each other? Are there any differences in successful quits depending on the use of a specific cessation aid or strategy? METHOD: We used repeated cross-sectional representative surveys in Norway for 2017, 2018, 2019 and 2020. The analytic sample consists of people aged 20 years or older who have ever smoked daily, more precisely current daily smokers with at least one quit attempt (n = 476), and former daily smokers who quit in 2012 or later (n = 397). Participants answered questions on cessation aids and strategies used at their last quit attempt. Logistic regression analysis was used to estimate the associations between cessation aids and strategies and sociodemographic and smoking-related variables and successful quit attempts. RESULTS: Fifty-six percent of people who ever smoked daily reported any use of cessation aids, and nicotine replacement therapy (NRT), snus and e-cigarettes were the most commonly used cessation aids. Snus and web/mobile use was associated with successful quits, while NRT was associated with unsuccessful quit attempts. When exclusive use was separated from the combined use of several aids, only snus was associated with successful quits. CONCLUSION: Snus use was found to be a "stand-alone" cessation aid, and only weakly associated with the use of other cessation aids. Further investigation of cessation aid preferences is needed, especially among smokers with little or no contact with health services and/or for whom traditional cessation aids have no appeal.

Chemical characterization of tobacco-free "modern" oral nicotine pouches and their position on the toxicant and risk continuums.

As compared with cigarette smoking, use of Swedish snus is associated with significantly fewer health risks. Nicotine pouches (NPs), a new form of oral nicotine product, are smokeless and tobacco-free, comprising a nicotine-containing cellulose matrix inside a fiber pouch. NPs are similar in appearance/use to snus, but without tobacco, have the potential to further reduce tobacco-related harm. This study aimed to evaluate toxicant levels of NPs to estimate their position on the tobacco/nicotine product continuums of toxicant delivery and risk. NPs, snus and nicotine replacement therapy products (NRTs) were analyzed for 24-26 compounds applicable to oral tobacco, and their levels were compared. Twenty of these compounds were further used to compare the toxicant profile of NPs, as well as estimated daily toxicant exposure from NP use, with that of tobacco/nicotine products spanning the risk continuum. Of the compounds measured, 22 (NPs), 22 (lozenge NRT), 20 (gum NRT), and 11 (snus) were not quantifiable. Compared with snus, NPs had lower levels of 10 HPHCs and comparable/undetectable levels of a further 13. Across the product categories, NPs and NRTs had the lowest toxicant profiles and estimations of relative toxicant exposure. Based on the present chemical analysis and estimated exposure, use of NPs appears likely to expose users to lower levels of toxic compounds than Swedish snus, which is recognized to offer reduced levels of harm than associated with tobacco smoking. We conclude that NPs should be placed close to NRTs on the tobacco/nicotine product toxicant delivery continuum, although further studies will be needed to confirm this.

Can alternative nicotine products put the final nail in the smoking coffin?

This review describes the evolution of smoking prevalence in countries with relatively high adoption of alternative nicotine products such as e-cigarettes, heated tobacco, and snus compared to neighboring countries where these products are less prevalent. The data indicate that countries with high adoption of alternative nicotine products have been able to achieve lower smoking rates. The findings suggest that adoption of alternative nicotine products may help in reduce smoking prevalence faster than traditional tobacco control measures solely focused on prevention and cessation.

Swedish snuff (snus) and risk of cardiovascular disease and mortality: prospective cohort study of middle-aged and older individuals.

BACKGROUND: Cigarette smoking is a well-known risk factor for cardiovascular disease (CVD), but whether smokeless tobacco such as snuff is associated with the risk of CVD is still unclear. We investigated the association of the use of Swedish oral moist snuff (snus) with a broad range of CVDs and CVD mortality. METHODS: We used data from a population-based cohort of 41,162 Swedish adults with a mean baseline age of 70 (56-94) years who completed questionnaires regarding snus use and other lifestyle habits and health characteristics. Participants were followed up for incident cardiovascular outcomes and death over 8 years through linkage to the Swedish National Patient and Death Registers. Hazard ratios (HR) were estimated by Cox proportional hazards regression. We conducted analyses among all subjects as well as among never smokers to reduce residual confounding from smoking. RESULTS: After adjustment for smoking and other confounders, snus use was not associated with myocardial infarction, heart failure, atrial fibrillation, aortic valve stenosis, abdominal aortic aneurysm, stroke, or CVD mortality. However, in never smokers, snus use was associated with a statistically significant increased risk of total and ischemic stroke (HRs [95% confidence intervals] = 1.52 [1.01-2.30] and 1.63 [1.05-2.54], respectively) and non-significantly positively associated with some other CVDs. CONCLUSIONS: In this middle-aged and elderly Swedish population, current Swedish snus use was not associated with the risk of major heart and valvular diseases, abdominal aortic aneurysm, or CVD mortality in the entire study population, but was linked to an increased risk of stroke in never smokers.

No association between moist oral snuff (snus) use and oral cancer: pooled analysis of nine prospective observational studies.

Aims: Worldwide, smokeless-tobacco use is a major risk factor for oral cancer. Evidence regarding the particular association between Swedish snus use and oral cancer is, however, less clear. We used pooled individual data from the Swedish Collaboration on Health Effects of Snus Use to assess the association between snus use and oral cancer. Methods: A total of 418,369 male participants from nine cohort studies were followed up for oral cancer incidence through linkage to health registers. We used shared frailty models with random effects at the study level, to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) adjusted for confounding factors. Results: During 9,201,647 person-years of observation, 628 men developed oral cancer. Compared to never-snus use, ever-snus use was not associated with oral cancer (adjusted HR 0.90, 95% CI: 0.74, 1.09). There were no clear trends in risk with duration or intensity of snus use, although lower intensity use (⩽ 4 cans/week) was associated with a reduced risk (HR 0.65, 95% CI: 0.45, 0.94). Snus use was not associated with oral cancer among never smokers (HR 0.87, 95% CI: 0.57, 1.32). Conclusions: Swedish snus use does not appear to be implicated in the development of oral cancer in men.

Prenatal nicotine exposure was associated with long-term impact on the cardiovascular system and regulation-Review.

AIM: The aim of this structured review was to discuss knowledge of nicotine use during pregnancy and long-term effects on children's cardiovascular function. METHODS: PubMed and MEDLINE were searched for original papers that covered various forms of nicotine exposure during pregnancy and this identified 314 papers published in English from inception of the databases to 1 March 2021. The research focus was prenatal exposure that had long-term effects on the cardiovascular system. The search was expanded from the reference list of the selected papers, which identified another 17 papers. RESULTS: The 34 original papers that were included covered 172,696 subjects from foetuses to 19 years of age. Cardiovascular autonomic dysfunction was discussed in 12 of the papers and 16 studies reported on blood pressure. The remaining studies covered structural or functional changes in arterial wall or heart. There were convincing data on autonomic dysfunction and increased blood pressure. Some data were conflicting and problems with misclassification of exposure were evident. CONCLUSION: Prenatal nicotine exposure was associated with long-term developmental changes in the cardiovascular system and regulation. There were no safe periods, doses or nicotine products during pregnancy and women should abstain when planning a pregnancy.

The health impact of smokeless tobacco products: a systematic review.

INTRODUCTION: The objective was to systematically review studies on health outcomes from smokeless tobacco (SLT) products. METHODS: We analysed published literature on the health outcomes from SLT use between 01/01/2015 to 01/02/2020, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol using PubMed, Embase, Scopus, and Google Scholar. RESULTS: Of 53 studies included, six were global, 32 from Asia, Middle East and Africa (AMEA), nine from USA and six from Europe. 'Poor'-rated studies predominated (23;43%), in particular, for global (4;66%) and AMEA (16;50%). Health outcomes differed between SLT-products and regions; those in AMEA were associated with higher mortality (overall, cancer, Coronary heart disease (CHD), respiratory but not cardiovascular disease (CVD)), and morbidity (CVD, oral and head and neck cancers), with odds ratios up to 38.7. European studies showed no excess mortality (overall, CVD, from cancers) or morbidity (ischemic heart disease (IHD), stroke, oral, head and neck, pancreatic or colon cancers) from several meta-analyses; single studies reported elevated risk of rectal cancer and respiratory disorders. Pooled study data showed protection against developing Parkinson's disease. US studies showed mixed results for mortality (raised overall, CHD, cancer and smoking-related cancer mortality; no excess risk of respiratory or CVD mortality). Morbidity outcomes were also mixed, with some evidence of increased IHD, stroke and cancer risk (oral, head and neck). No studies reported on switching from cigarettes to SLT-products. CONCLUSION: Our review demonstrates stark differences between different SLT-products in different regions, ranging from zero harm from European snus to greatly increased health risks in AMEA. The literature on the safety profile for SLT-products for harm reduction is incomplete and potentially misinforming policy and regulation.

Tobacco Smoking and Smokeless Tobacco Use among Domestic and International Medical Students in Hungary.

BACKGROUND: Medical students as future physicians will have an important role in tobacco control; therefore, their tobacco use behavior is of particular interest. Consumption of combustible tobacco (cigarettes, waterpipes, cigars, and pipes) is prevalent throughout Europe, whereas smokeless tobacco use is common mainly in the Nordic countries. Objectives: Aim of our study is to assess tobacco use among medical students from different countries studying in Hungary with special focus on students from Norway where smokeless tobacco is widely used. A self-administered questionnaire survey was carried out to measure current tobacco use. Results: The survey included 1337 students from Hungary, Norway, Germany, and from other countries (Multinational group). The lowest prevalence of cigarette smoking was found among students from Norway (13.0%) when compared with students from Hungary (21.5%), Germany (34.2%), or with students in the Multinational group (29.5%). Conversely, prevalence of smokeless tobacco use was the highest among students from Norway (40.9%) when compared with students from Hungary (1.4%), Germany (2.6%), or with students in the Multinational group (6.2%). Waterpipes, cigars, and pipes were rarely used, mostly only 1-3 times a month in all groups. More than half of Norwegian students used some form of tobacco (smokeless and/or combustible tobacco). Conclusions: Considering the impending role of medical students in tobacco control, faculties of medicine should sensitize their students on the topic of possible health risks associated with combustible and smokeless tobacco products. Culturally tailored tobacco cessation programs need to be offered to medical students coming from different cultural backgrounds.

Potential Application of USP Paddle and Basket Dissolution Methods in Discriminating for Portioned Moist Snuff and Snus Smokeless Tobacco Products.

The focus of the study was to develop discriminatory dissolution methods for portioned snus and moist snuff sub-categories of smokeless tobacco products (STPs) using USP basket and paddle apparatuses. Skoal Classic Wintergreen (SCW) and CORESTA CRP1.1 pouches were used as test products. The dissolution was performed at 10, 20, 30, 40, and 50 rpm basket or paddle speed in 500 ml artificial saliva pH 6.8. The products were also characterized for assay, pH, particle size, and loss on drying. The dissolution profiles were evaluated for amount/% of nicotine dissolved, time to reach plateau, and profiles comparison by f2 and f1 factors. The nicotine assay was 13.3 ± 0.2 and 7.6 ± 0.1 mg/pouch for SCW and CRP1.1, respectively. The nicotine dissolved in 30 min from SCW and CRP1.1 were 38.4-81.8 and 37.6-88.1, and 50.5-64.9 and 72.3-92.1% by paddle and basket methods, respectively. The f2 and f1 values were ≤ 39.2 and ≥ 42.1 and ≤ 43.2 and ≥ 34.1 for basket methods and paddle methods. RSD were less than 20% at all points of dissolution profiles, and dissolution plateau were achieved in 30 min at some of the tested conditions. In summary, dissolution methods based on basket and paddle can be used as a performance test for STPs.

Tobacco harm reduction: Past history, current controversies and a proposed approach for the future.

Tobacco harm reduction remains a controversial topic in tobacco control. Tobacco harm reduction involves providing tobacco users who are unwilling or unable to quit using nicotine products with less harmful nicotine-containing products for continued use. The skepticism towards harm reduction is based in part on the experience with low-yield tar/nicotine cigarettes, which were presumed to be associated with lower health risks than higher yield cigarettes and marketed as such by cigarette manufacturers. Only later did the field learn that these cigarettes were a deceptive way for cigarette manufacturers to allay the health concerns over cigarette smoking. Since this experience, there has been a proliferation of tobacco products that might potentially serve as a means to reduce tobacco harm. Some members of the tobacco control community believe that these products have great potential to reduce mortality and morbidity among smokers who completely switch to them. Others believe that we will be addicting another generation to tobacco products. This paper reviews the past history, the current tobacco landscape and controversies, and an approach that might rapidly reduce the yearly half-million deaths associated with cigarette smoking in the U.S.

Meningococcal carriage in Norwegian teenagers: strain characterisation and assessment of risk factors.

Teenagers have a higher risk of invasive meningococcal disease (IMD) than the general population. This cross-sectional study aimed to characterise strains of Neisseria meningitidis circulating among Norwegian teenagers and to assess risk factors for meningococcal carriage. Oropharyngeal swabs were collected from secondary-school students in southeastern Norway in 2018-2019. Meningococcal isolates were characterised using whole genome sequencing. Risk factors for meningococcal carriage were assessed from questionnaire data. Samples were obtained from 2296 12-24-year-olds (majority 13-19-year-olds). N. meningitidis was identified in 167 (7.3%) individuals. The highest carriage rate was found among 18-year-olds (16.4%). Most carriage isolates were capsule null (40.1%) or genogroup Y (33.5%). Clonal complexes cc23 (35.9%) and cc198 (32.3%) dominated and 38.9% of carriage strains were similar to invasive strains currently causing IMD in Norway. Use of Swedish snus (smokeless tobacco) (OR 1.56, 95% CI 1.07-2.27), kissing >two persons/month (OR 2.76, 95% CI 1.49-5.10) and partying >10 times/3months (OR 3.50, 95% CI 1.45-8.48) were associated with carriage, while age, cigarette smoking, sharing of drinking bottles and meningococcal vaccination were not. The high meningococcal carriage rate among 18-year-olds is probably due to risk-related behaviour. Use of Swedish snus is possibly a new risk factor for meningococcal carriage. Almost 40% of circulating carriage strains have invasive potential.