Koen Van Herck

Effectiveness of rotavirus vaccination in prevention of hospital admissions for rotavirus gastroenteritis among young children in Belgium: case-control study

Objective To evaluate the effectiveness of rotavirus vaccination among young children in Belgium. Design Prospective case-control study. Setting Random sample of 39 Belgian hospitals, February 2008 to June 2010. Participants 215 children admitted to hospital with rotavirus gastroenteritis confirmed by polymerase chain reaction and 276 age and hospital matched controls. All children were of an eligible age to have received rotavirus vaccination (that is, born after 1 October 2006 and aged ≥14 weeks). Main outcome measure Vaccination status of children admitted to hospital with rotavirus gastroenteritis and matched controls. Results 99 children (48%) admitted with rotavirus gastroenteritis and 244 (91%) controls had received at least one dose of any rotavirus vaccine (P<0.001). The monovalent rotavirus vaccine accounted for 92% (n=594) of all rotavirus vaccine doses. With hospital admission as the outcome, the unadjusted effectiveness of two doses of the monovalent rotavirus vaccine was 90% (95% confidence interval 81% to 95%) overall, 91% (75% to 97%) in children aged 3-11 months, and 90% (76% to 96%) in those aged ≥12 months. The G2P[4] genotype accounted for 52% of cases confirmed by polymerase chain reaction with eligible matched controls. Vaccine effectiveness was 85% (64% to 94%) against G2P[4] and 95% (78% to 99%) against G1P[8]. In 25% of cases confirmed by polymerase chain reaction with eligible matched controls, there was reported co-infection with adenovirus, astrovirus and/or norovirus. Vaccine effectiveness against co-infected cases was 86% (52% to 96%). Effectiveness of at least one dose of any rotavirus vaccine (intention to vaccinate analysis) was 91% (82% to 95%). Conclusions Rotavirus vaccination is effective for the prevention of admission to hospital for rotavirus gastroenteritis among young children in Belgium, despite the high prevalence of G2P[4] and viral co-infection.

Rotavirus vaccines in Belgium: policy and impact.

Background: The current Belgian experience with rotavirus vaccination provides a unique perspective to look at the effect of vaccination. Shortly after introduction, a nation-wide recommendation was issued and despite the fact that both rotavirus vaccines are offered through partial reimbursement, vaccine uptake has already reached a high level (at least 90%). Methods: For the purpose of looking at the effectiveness of the Belgian rotavirus vaccination policy, 3 years after introduction, we retrospectively collated the publicly available data on the number of laboratory-confirmed rotavirus cases reported to a national network of sentinel laboratories during 1999 to 2010 and compared them with the available data on hospitalizations due to rotavirus gastroenteritis. Results: Both data sources (reported laboratory-diagnosed cases to a sentinel network as well as data on hospitalizations due to rotavirus gastroenteritis) show a decrease in the number of rotavirus infections and a 4- to 6-week delay in the onset of disease and the peak of incidence in the postvaccination period. Conclusions: Because this decline coincides with the increased vaccine uptake and is sustained during consecutive rotavirus seasons, the effect is mainly attributed to the rotavirus vaccination. The rapid increase in vaccine coverage, despite the partial reimbursement for the vaccines, is remarkable. Continued postlicensure surveillance is necessary to further investigate the effectiveness of the vaccines and to document the public health impact of the vaccination in reducing disease burden.

Malnutrition and associated factors in nursing home residents: a cross-sectional, multi-centre study.

BACKGROUND & AIMS Malnutrition is a common problem in the elderly living in nursing homes. A clear understanding of associated factors is missing. The aim of this study was to evaluate prevalence of malnutrition and to determine factors independently associated with malnutrition in this setting. METHODS A cross-sectional, multi-centre study was conducted in 23 nursing homes in Flanders, Belgium. The nutritional status was assessed using the Mini Nutritional Assessment (MNA). Data on possible associated factors were collected using validated scales. RESULTS The study included 1188 elderly residents; 38.7% were at risk for malnutrition and 19.4% were malnourished. The presence of a wound/pressure ulcer, a recent hospitalization (<3 months ago), being involved in a tailored nutritional intervention, and suffering from a lower cognitive state were significantly associated with malnutrition. Receiving additional meals provided by family members was negatively associated with malnutrition. CONCLUSION Malnutrition is a prevalent problem in nursing homes in Flanders. Systematic screening and well-defined tailored interventions should be further developed and evaluated in this population at risk.

Impact of rotavirus vaccination on laboratory confirmed cases in Belgium

Rotavirus vaccines were introduced in Belgium in 2006 and recommended in the universal schedule in January 2007. We measured the impact of rotavirus vaccination through an active laboratory-based surveillance system. In 2008, the number of laboratory confirmed rotavirus cases declined by 61.4% (95% CI 60.2-62.6%) compared to the 2005-2006 pre-vaccination period, with the highest decline in children<1 year (80.1%; 95% CI 78.7-81.4%). The rotavirus season was delayed compared to pre-vaccination seasons. Laboratory data provide a crude estimation of vaccination impact, but analysis of in-patient data will be needed to assess the impact on severe disease.

Antibody persistence and immune memory in healthy adults following vaccination with a two-dose inactivated hepatitis A vaccine: Long-term follow-up at 15 years†

Long‐term persistence of vaccine‐induced immune response in adults was assessed annually for 15 years following primary immunization with a two‐dose inactivated hepatitis A vaccine. In 1992, 119 and 194 subjects aged 17–40 years and naïve for hepatitis A virus (HAV) were enrolled in two studies to receive 1,440 ELISA units (El.U) of inactivated hepatitis A vaccine (Havrix™, GlaxoSmithKline Biologicals, Belgium) according to a standard 0, 6 or an extended 0, 12 months schedule, respectively. Serum samples were taken 1 month after the second vaccine dose and every consecutive year up to 15 years after primary vaccination for measurement of anti‐HAV antibody concentrations (NCT00291876 and NCT00289757).

The Combined Relationship of Occupational and Leisure-Time Physical Activity With All-Cause Mortality Among Men, Accounting for Physical Fitness

The aim of this study was to assess the combined relationship of occupational physical activity and leisure-time physical activity with all-cause mortality among men, while accounting for physical fitness. The prospective Belgian Physical Fitness Study included 1,456 male workers aged 40-55 years who were free of coronary heart disease at baseline. Baseline data were collected through questionnaires and clinical examinations from 1976 to 1978. To estimate physical fitness, a submaximal graded exercise test was performed on a bicycle ergometer. Total mortality was registered during a mean follow-up period of 16.9 years. Main results were obtained through Cox proportional hazards regression analysis. A total of 145 deaths were registered during follow-up. After adjustment for confounders, a significantly increased mortality rate was observed in workers who had low levels of both physical activity types (hazard ratio = 2.07, 95% confidence interval: 1.03, 4.19) but also in workers combining high occupational physical activity and low leisure-time physical activity (hazard ratio = 2.04, 95% confidence interval: 1.07, 3.91); the latter finding was particularly pronounced among workers with a low physical fitness level. The present results confirm the existence of a complex interplay among different physical activity settings and fitness levels in predicting mortality.

Benefits of early hepatitis B immunization programs for newborns and infants.

Despite the availability of safe and effective hepatitis B virus (HBV) vaccines for >20 years, strategies targeting risk groups failed to sufficiently control hepatitis B disease at the population level; this is mainly because of difficulties in risk identification and in program implementation. Hence, the global burden of disease of HBV still is substantial. The World Health Organization recommends universal vaccination against hepatitis B to ultimately eliminate HBV; this recommendation had been progressively implemented to reach 168 countries with a universal program by the end of 2006. However, hepatitis B immunization is currently becoming endangered of losing its place on the agendas of governments, agencies, and international organizations, mainly because of the increasing success of these immunization programs and the interest in newer vaccine-preventable diseases and the related programs. This publication aims to show that vaccination programs targeting newborns and infants are preferable to achieve this goal. The benefits of universal HBV vaccination for newborns and infants are: higher impact on chronic carrier rate and transmission; established potential of high vaccine coverage in this age group; opportunities to combine HBV vaccination with existing universal vaccination programs for newborns and infants; and impact on perinatal transmission, if vaccination is started shortly after birth. Moreover, the safety, immunogenicity, and long-term efficacy of newborn and infant HBV vaccination have been proven extensively. In summary, newborn and infant HBV vaccination programs should be considered the preferred strategy, capable of providing important and sustained impact on global HBV incidence, even if they have a delayed impact on sexual transmission of HBV.

A review of the efficacy, immunogenicity and tolerability of a combined hepatitis A and B vaccine

Hepatitis A and B are two of the most common vaccine-preventable liver diseases and continue to be a significant cause of morbidity and mortality worldwide, with their severity related to the individuals age upon initial infection. Twinrix (GlaxoSmithKline), a combined vaccine providing protection against both hepatitis A and B, has been available in more than 72 countries worldwide since 1997. This paper provides a critical review of clinical data on the efficacy, immunogenicity and tolerability of the combined vaccine, with particular focus on the clinical benefits of dual vaccination.Hepatitis A and B are two of the most common vaccine-preventable liver diseases and continue to be a significant cause of morbidity and mortality worldwide, with their severity related to the individual’s age upon initial infection. Twinrix™ (GlaxoSmithKline), a combined vaccine providing protection against both hepatitis A and B, has been available in more than 72 countries worldwide since 1997. This paper provides a critical review of clinical data on the efficacy, immunogenicity and tolerability of the combined vaccine, with particular focus on the clinical benefits of dual vaccination.

Model based estimates of long-term persistence of inactivated hepatitis A vaccine-induced antibodies in adults.

BACKGROUND In this paper, we review the results of existing statistical models of the long-term persistence of hepatitis A vaccine-induced antibodies in light of recently available immunogenicity data from 2 clinical trials (up to 17 years of follow-up). METHODS Healthy adult volunteers monitored annually for 17 years after the administration of the first vaccine dose in 2 double-blind, randomized clinical trials were included in this analysis. Vaccination in these studies was administered according to a 2-dose vaccination schedule: 0, 12 months in study A and 0, 6 months in study B (NCT00289757/NCT00291876). Antibodies were measured using an in-house ELISA during the first 11 years of follow-up; a commercially available ELISA was then used up to Year 17 of follow-up. Long-term antibody persistence from studies A and B was estimated using statistical models for longitudinal data. Data from studies A and B were modeled separately. RESULTS A total of 173 participants in study A and 108 participants in study B were included in the analysis. A linear mixed model with 2 changepoints allowed all available results to be accounted for. Predictions based on this model indicated that 98% (95%CI: 94-100%) of participants in study A and 97% (95%CI: 94-100%) of participants in study B will remain seropositive 25 years after receiving the first vaccine dose. Other models using part of the data provided consistent results: ≥95% of the participants was projected to remain seropositive for ≥25 years. CONCLUSION This analysis, using previously used and newly selected model structures, was consistent with former estimates of seropositivity rates ≥95% for at least 25 years.

Occupational and leisure time physical activity in contrasting relation to ambulatory blood pressure

BackgroundWhile moderate and vigorous leisure time physical activities are well documented to decrease the risk for cardiovascular disease, several studies have demonstrated an increased risk for cardiovascular disease in workers with high occupational activity. Research on the underlying causes to the contrasting effects of occupational and leisure time physical activity on cardiovascular health is lacking. The aim of this study was to examine the relation of objective and self-report measures of occupational and leisure time physical activity with 24-h ambulatory systolic blood pressure (BP).MethodsResults for self-reported physical activity are based on observations in 182 workers (60% male, mean age 51 years), while valid objective physical activity data were available in 151 participants. The usual level of physical activity was assessed by 5 items from the Job Content Questionnaire (high physical effort, lifting heavy loads, rapid physical activity, awkward body positions and awkward positions of head or arms at work) and one item asking about the general level of physical activity during non-working time. On a regular working day, participants wore an ambulatory BP monitor and an accelerometer physical activity monitor during 24 h. Associations were examined by means of Analysis of Covariance.ResultsWorkers with an overall high level of self-reported occupational physical activity as well as those who reported to often lift heavy loads at work had a higher mean systolic BP at work, at home and during sleep. However, no associations were observed between objectively measured occupational physical activity and BP. In contrast, those with objectively measured high proportion of moderate and vigorous leisure time physical activity had a significantly lower mean systolic BP during daytime, while no differences were observed according to self-reported level of leisure time physical activity.ConclusionsThese findings suggest that workers reporting static occupational physical activities, unlike general physically demanding tasks characterized by dynamic movements of large muscle groups, are related to a higher daily systolic BP, while high objective levels of moderate and vigorous leisure time physical activity are related to lower daytime systolic BP. Ambulatory systolic BP may be a physiological explanatory factor for the contrasting effects of occupational and leisure time physical activity.