Changes in pneumococcal carriage prevalence and factors associated with carriage in Norwegian children, four years after introduction of PCV13.

BACKGROUND: Streptococcus pneumoniae carriage is often asymptomatic but can cause invasive pneumococcal disease. Pneumococcal carriage is a prerequisite for disease, with children as main reservoir and transmitters. Childhood carriage can therefore be used to determine which serotypes circulate in the population and which may cause disease in the non-vaccinated population. In 2006, a pneumococcal conjugate vaccine (PCV7) was introduced into the Norwegian Childhood Immunisation Programme, which was replaced by the more valent PCV13 in 2011. We investigated changes in pneumococcal carriage prevalence 4 years after switching to PCV13 compared to three previous surveys, and analysed factors associated with carriage in children. METHODS: We conducted a cross-sectional study in Norway, autumn 2015, among children attending day-care centres. We collected questionnaire data and nasopharyngeal swabs to identify pneumococcal serotypes. We compared the carriage prevalence in 2015 with surveys conducted in the same setting performed before widespread vaccination (2006; n = 610), 2 years after PCV7 introduction (2008; n = 600), and 2 years after switching to PCV13 (2013; n = 874). Using multilevel logistic regression we determined the association between pneumococcal carriage and previously associated factors. RESULTS: In 2015, 896 children participated, with age ranging from 8 to 80 months. The overall carriage prevalence was 48/100 children [95%CI 44-53] in 2015, 38% [29-46] lower than in 2006 pre-PCV7, and 23% [12-32] lower than in 2013, 2 years after switching to PCV13. The PCV13 carriage prevalence was 2.8/100 children [1.9-4.2] in 2015. Increasing age (p < 0.001), recent antimicrobial use (odds ratio = 0.42 [0.21-0.57]) and being vaccinated (odds ratio = 0.37 [0.29-0.47]) were negatively associated with carriage. CONCLUSIONS: Our study showed a continued decrease in overall pneumococcal carriage, mainly fuelled by the decline in vaccine serotypes after vaccine introduction. Childhood vaccination with PCV13 should be continued to keep low PCV13 carriage, transmission and disease. Furthermore, the low prevalence of PCV13-type carriage in children endorse the choice of not recommending PCV13 in addition to the 23-valent pneumococcal polysaccharide vaccine to most medical risk groups in Norway, as little disease caused by these serotypes can be expected.

A review of the evidence to inform pneumococcal vaccine recommendations for risk groups aged 2 years and older.

For decades, vaccination with the 23-valent polysaccharide pneumococcal vaccine (PPV23) has been available for risk groups aged ⩾2 years to prevent invasive pneumococcal disease (IPD). Recently, a 13-valent pneumococcal conjugated vaccine (PCV13) has been licensed for use in all age groups. PCV13 may induce better protection than PPV23 because of different immunogenic properties. This called for a revision of vaccine recommendations for risk groups. We therefore reviewed literature on risk groups for IPD, and effectiveness and safety of pneumococcal vaccines and supplemented that with information from public health institutes, expert consultations and data on IPD epidemiology. We included 187 articles. We discuss the implications of the heterogenic vulnerability for IPD within and between risk groups, large indirect effects of childhood immunization, and limited knowledge on additional clinical benefits of PCV13 in combination with PPV23 for the Norwegian recommendations. These are now step-wise and consider the need for vaccination, choice of pneumococcal vaccines, and re-vaccination interval by risk group.

Mechanisms underlying muscle fatigue differ between multiple sclerosis patients and controls: a combined electrophysiological and neuroimaging study.

Increased sense of fatigue is an important and conspicuous symptom in multiple sclerosis (MS). Muscle fatigue is associated with increased sense of fatigue in MS (Steens et al., 2011). The aim of this study was to investigate mechanisms that can explain muscle fatigue in MS patients and controls. We assessed changes in cortical activation (BOLD), voluntary activation (twitch interpolation) and muscle force during a sustained maximal voluntary contraction (MVC) in twenty MS patients and twenty healthy controls. In control participants, individual differences in force decline (mean 65% MVC, 8 SD) during the sustained maximal contraction could be accounted for by differences in maximal voluntary force (R(2): 0.49, p = 0.001); stronger participants presented a larger force decline. The small decline in voluntary activation (mean 7.8%, 11.8 SD) did not contribute significantly to the force decline. During the sustained contraction, the force decline was accompanied by an increase in cortical activation in the main motor areas. In MS patients, the differences in the decline in force (mean 67% MVC, 9 SD) were significantly associated (R(2): 0.51, p = 0.001) with a decline in voluntary activation (mean 20.1%, 20.6 SD) and not with maximal force or decline in rest twitch. The corresponding cortical activation in motor areas showed an increase in the first two intervals of the sustained contraction but declined during the last interval. Our data indicate that muscle fatigue during a sustained contraction in MS patients is associated with changes in the voluntary activation that are not sufficiently compensated by increased cortical activation. Control participants, however, show increased cortical activation to compensate for these fatigue-related changes in voluntary activation and the major cause of force decline is therefore to be found in the periphery (muscles).

Easy access to vaccination was important for adherence during the 2016-2019 HPV catch-up vaccination in Norway.

Between September and October 2019, the Norwegian Institute for Public Health (NIPH) surveyed women born between 1991 and 1996 who were offered catch-up vaccination for human papilloma virus (HPV). The aim was to identify determinants of vaccine schedule adherence. A random sample of 10,000 women who were offered catch-up vaccination were invited to participate in the survey. We defined adherence as receiving all three doses. Determinants of HPV vaccination adherence were investigated using descriptive, univariable and multivariable logistic regression analyses providing adjusted odds ratios (aOR). Data from 3,762 respondents who received at least one dose were included. Overall, 92.1% (95% CI = 89.3-91.9) of those initiating vaccination adhered to the complete schedule. The following factors were significantly associated with HPV vaccination adherence compared to non-adherence: country of origin (aOR = 0.43; 95% CI = 0.47-0.97), having children (aOR = 0.51; 95% CI = 0.35-0.73), ease of finding out where to get vaccinated (aOR = 1.94; 95% CI = 1.69-2.23), preference for receiving information from health authorities (aOR = 1.37; 95% CI = 1.04-1.81) and vaccination being readily available (aOR = 2.28; 95% CI = 1.50-3.37). Information from NIPH via SMS and social media were negatively associated for Norwegians (aOR = 0.68, 95% CI = 0.46-1.01) and positively associated for those whose country of origin was not Norway (aOR = 1.48, 95% CI = 0.69-3.14; not significant). Those who did not adhere to the full vaccination schedule reported that they had forgotten (40.4%; 95% CI = 33.5-47.8) or had no time (32.9%; 95% CI = 26.2-40.4). Despite NIPH's targeted communication campaign, the main barriers for HPV vaccination adherence were difficulty to find out where to get the vaccine, forgetting to take the vaccine or not having time to complete the schedule.

Sociodemographic determinants of catch-up HPV vaccination completion between 2016-2019 in Norway.

Between 2016 and 2019, a catch-up human papillomavirus (HPV) vaccination took place in Norway for women born between 1991 and 1996. The aim of this study was to identify sociodemographic determinants of complete vaccination (3 doses) and partial vaccination (1-2 doses). A random sample of 10,000 women who were offered catch-up HPV vaccination were invited. We assessed the association between sociodemographic characteristics and vaccination completion using univariable and multivariable multinomial logistic regression.Of 4,967 respondents, 3,464 (63%) received complete vaccination and 298 (7%) received partial vaccination. 30% did not receive any vaccination and functioned as reference group. Compared with having Norwegian caregivers, having a caregiver from non-western countries decreased the odds of partial and complete vaccination (aOR = 0.57; 95%CI = 0.35-0.95 and aOR = 0.57; 95%CI = 0.44-0.74). Having a caregiver from other western countries decreased the odds of complete vaccination (aOR = 0.72; 95%CI = 0.52-0.98). Residing in Norway for 10 years or longer significantly increased the odds of complete vaccination (aOR = 2.65; 95%CI = 1.58-4.43). Being in a relationship significantly increased the odds of partial vaccination compared with being single (aOR = 1.50; 95%CI = 1.02-2.21). Being married (aOR = 0.66; 95%CI = 0.50-0.86) and having children (aOR = 0.53; 95%CI = 0.42-0.68) decreased the odds of complete vaccination. Having university education increased the odds of both partial and complete vaccination (aOR = 2.19; 95%CI = 1.47-3.25 and aOR = 4.11; 95%CI = 3.33-5.06).Having a caregiver born outside of Norway, having children and being married decreased the odds of receiving complete HPV vaccination. This highlights the need to target communication around HPV vaccination toward different ethnic communities and include more specific messaging that having children and being married does not necessarily prevent HPV infections.

International links between Streptococcus pneumoniae vaccine serotype 4 sequence type (ST) 801 in Northern European shipyard outbreaks of invasive pneumococcal disease.

BACKGROUND: Pneumococcal disease outbreaks of vaccine preventable serotype 4 sequence type (ST)801 in shipyards have been reported in several countries. We aimed to use genomics to establish any international links between them. METHODS: Sequence data from ST801-related outbreak isolates from Norway (n = 17), Finland (n = 11) and Northern Ireland (n = 2) were combined with invasive pneumococcal disease surveillance from the respective countries, and ST801-related genomes from an international collection (n = 41 of > 40,000), totalling 106 genomes. Raw data were mapped and recombination excluded before phylogenetic dating. RESULTS: Outbreak isolates were relatively diverse, with up to 100 SNPs (single nucleotide polymorphisms) and a common ancestor estimated around the year 2000. However, 19 Norwegian and Finnish isolates were nearly indistinguishable (0-2 SNPs) with the common ancestor dated around 2017. CONCLUSION: The total diversity of ST801 within the outbreaks could not be explained by recent transmission alone, suggesting that harsh environmental and associated living conditions reported in the shipyards may facilitate invasion of colonising pneumococci. However, near identical strains in the Norwegian and Finnish outbreaks does suggest that transmission between international shipyards also contributed to those outbreaks. This indicates the need for improved preventative measures in this working population including pneumococcal vaccination.