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.

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.

Introduction: The ability of Swedish snus to serve as a smoking cessation aid has been documented in several observational, population surveys from Scandinavia, but randomised clinical trials provide more reliable information on efficacy. Aims: To perform a systematic review and meta-analysis of randomised clinical trials of Swedish snus as an aid to smoking cessation. Methods: Literature searches were conducted in MedLine, Cochrane Library, and Embase to identify relevant clinical trials. The primary outcome was defined as biologically confirmed smoking cessation during around six months. Meta-analyses based on primary subject data tested for effect of allocated treatment as well as selected baseline characteristics. Results: There were two relevant clinical trials, one conducted at five sites in the US (n = 250), the other at two sites in Serbia (n = 319). Based on the primary outcome, success was higher in the treated group in both Serbia (5.7% vs 1.9%) and the US (4.0% vs 1.6%). Meta-analysis estimated the relative success rate at 2.83 (95% CI 1.03–7.75), which was of borderline significance (exact p = 0.06, chi-squared p = 0.03). For smoking cessation in the last 4 weeks of each study, rates were 12.4% for snus and 6.6% for placebo (RR 1.86, 95% CI 1.09-3.18). Efficacy of snus was not clearly related to any baseline characteristic. Conclusions: Swedish snus increased quit rates similarly in US and Serbia. These results confirm and extend previous information based on observational population surveys.