Impact analysis of rotavirus vaccination in various geographic regions in Western Europe.

BACKGROUND: Universal mass vaccination (UMV) against rotavirus has been implemented in many but not all European countries. This study investigated the impact of UMV on rotavirus incidence trends by comparing European countries with UMV: Belgium, England/Wales and Germany versus countries without UMV: Denmark and the Netherlands. METHODS: For this observational retrospective cohort study, time series data (2001-2016) on rotavirus detections, meteorological factors and population demographics were collected. For each country, several meteorological and population factors were investigated as possible predictors of rotavirus incidence. The final set of predictors were incorporated in negative binomial models accounting for seasonality and serial autocorrelation, and time-varying incidence rate ratios (IRR) were calculated for each age group and country separately. The overall vaccination impact two years after vaccine implementation was estimated by pooling the results using a random effects meta-analyses. Independent t-tests were used to compare annual epidemics in the pre-vaccination and post-vaccination era to explore any changes in the timing of rotavirus epidemics. RESULTS: The population size and several meteorological factors were predictors for the rotavirus epidemiology. Overall, we estimated a 42% (95%-CI 23;56%) reduction in rotavirus incidence attributable to UMV. Strongest reductions were observed for age-groups 0-, 1- and 2-years (IRR 0.47, 0.48 and 0.63, respectively). No herd effect induced by UMV in neighbouring countries was observed. In all UMV countries, the start and/or stop and corresponding peak of the rotavirus season was delayed by 4-7 weeks. CONCLUSIONS: The introduction of rotavirus UMV resulted in an overall reduction of 42% in rotavirus incidence in Western European countries two years after vaccine introduction and caused a change in seasonal pattern. No herd effect induced by UMV neighbouring countries was observed for Denmark and the Netherlands.

Can Flanders resist the measles outbreak? Assessing vaccination coverage in different age groups among Flemish residents.

The Belgian strategic plan to eliminate measles contains several vaccination strategies including routine immunisation programmes and catch-up campaigns. A new expanded programme on immunisation-based survey (2016) assessed the uptake of the recommended measles-mumps-rubella (MMR) vaccine in three different cohorts: toddlers, adolescents and parents of toddlers. A two-stage cluster sampling technique was used to select 875 toddlers (age 18-24 months) and 1250 adolescents (born in 2000) from 107 municipalities in Flanders. After consent of the parent(s), 746 (85.2%) families of toddlers and 1012 (81.0%) families of adolescents were interviewed at home. Measles vaccination coverage was high at 18-24 months (96.2%) and 81.5% were vaccinated at recommended age. Toddlers who had two siblings or a non-working mother or changed vaccinator were more at risk for not being vaccinated. Coverage of the teenager dose reached 93.5% and was lower in adolescents with educational underachievement or whose mother was part-time working or with a non-Belgian background. Only 56.0% of mothers and 48.3% of fathers remembered having received at least one measles-containing vaccine. Although measles vaccination coverage in toddlers meets the required standards for elimination, administration of the teenager dose of MMR vaccine and parent compliance to the recent measles catch-up campaign in Flanders leave room for improvement.

Rotavirus vaccination coverage and adherence to recommended age among infants in Flanders (Belgium) in 2012.

In Belgium, rotavirus vaccination has been recommended and partially reimbursed since October 2006. Through a retrospective survey in 2012, we estimated the coverage rate of the rotavirus vaccination in Flanders among infants born in 2010. Using a standardised questionnaire, 874 families were interviewed at home, collecting information on demographic characteristics, socio-economic background and documented vaccination history (updated from medical files and vaccination database, if needed). Adherence to the recommended age for vaccination (8, 12 and 16 weeks) was also assessed. The coverage rate for two doses of rotavirus vaccination was 92.2% (95% confidence interval: 90.2-93.8). Respectively 31.7% and 10.1% of the children received their first and second dose at the recommended age. Incomplete vaccination was often a deliberate choice of the parents. Only eight children (1%) were vaccinated after the maximum age of 26 weeks. Factors identified by multiple logistic regression as related to incomplete vaccination were: living in the province of Antwerp, unemployed mother, and three or more older siblings in the household. Four years after introduction, the coverage rates were surprisingly high for a vaccine that is not fully reimbursed and not readily available in the vaccinator's fridge, which is the case for the other recommended infant vaccines.

Rumen metabolism of 22:6n-3 in vitro is dependent on its concentration and inoculum size, but less dependent on substrate carbohydrate composition.

Ruminal disappearance of linoleic and linolenic acid has been studied extensively. Less is known of the metabolism of docosahexaenoic acid (22:6n-3). The aim of this study was to identify factors which affect the disappearance of 22:6n-3 during in vitro batch incubations using rumen fluid from sheep. In experiment 1, the effect of the rumen fluid/buffer ratio (0.2 or 0.4), substrate (cellulose or cellulose/glucose), time of 22:6n-3 addition (0.08 mg/mL after 0 or 6 h of incubation) and incubation time (24 or 48 h) was evaluated. A mixture design was used in experiment 2 to evaluate the effect of carbohydrate type (cellulose, glucose, cellobiose and starch) on 22:6n-3 disappearance (0.08 mg/mL). In experiment 3, several concentrations of 22:6n-3 (0.05-0.30 mg/mL) were evaluated with different substrate mixtures (combinations of cellobiose, starch and cellulose). In a final experiment, the effect of the rumen fluid/buffer ratio (0.20, 0.35 and 0.50) and substrate (glucose, cellobiose and starch) was evaluated. In this experiment, 22:6n-3 was added as a proportion of rumen fluid ranging from 0.1 to 0.4 mg/mL rumen fluid, contrary to former experiments where concentrations were relative to culture medium. Low levels of 22:6n-3 (0.05 mg/mL) allowed extensive metabolism whereas increasing amounts of 22:6n-3 hampered its disappearance. A greater proportion of rumen fluid resulted in increased disappearance of 22:6n-3. The effect of carbohydrate type was small compared with the former two factors. These results suggest that in vitro metabolism of 22:6n-3 is mostly dictated by the conditions at the start of the incubation, i.e., inoculum, probably reflecting the density of bacteria able to metabolize 22:6n-3.

Higher proportion of G2P[4] rotaviruses in vaccinated hospitalized cases compared with unvaccinated hospitalized cases, despite high vaccine effectiveness against heterotypic G2P[4] rotaviruses.

The overall vaccine effectiveness of the monovalent rotavirus vaccine in an observational, prospective, multicentre, hospital-based case-control study in Belgium (RotaBel) was 90%. However, rotavirus genotype and co-infecting pathogens are important parameters to take into account when assessing vaccine effectiveness. In this study we specifically investigated the effect of rotavirus genotypes and co-infecting pathogens on vaccine effectiveness of the monovalent vaccine. In addition, we also investigated the effect of co-infecting pathogens on disease severity. From February 2008 to June 2010 stool samples of rotavirus gastroenteritis cases of a random sample of 39 Belgian hospitals were collected and subsequently genotyped. Fisher's exact tests were performed to investigate the relationships between rotavirus genotype, co-infecting pathogens and disease severity. The vaccine effectiveness of a full series of the monovalent rotavirus vaccine against hospitalized rotavirus gastroenteritis caused by G1P[8] rotavirus strains was 95% (95% CI 77.5-98.7). Against G2P[4], the vaccine effectiveness was 85% (95% CI: 63.7-93.8). G4P[8]- and G3P[8]-specific vaccine effectiveness was 90% (95% CI 19.2-98.7) and 87% (95% CI -5.2 to 98.4), respectively. A post-hoc analysis showed that the genotype distribution was significantly related to the vaccination status (p <0.001), whereby G2P[4] strains were proportionally more prevalent in vaccinated cases than in unvaccinated cases. No statistical associations were found between co-infection status and vaccination status, Vesikari severity score or rotavirus genotype. The high vaccine effectiveness against the individual genotypes implies robust protection of the monovalent rotavirus vaccine against hospitalized rotavirus gastroenteritis caused by the major human rotavirus genotypes. The prevalence of G2P[4] requires continued monitoring.