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Papers by baudouin standaert

Introduction: Rotavirus (RV) infection is the major cause of diarrhoea in children Methods: For e... more Introduction: Rotavirus (RV) infection is the major cause of diarrhoea in children Methods: For ethical and logistic reasons it is very difficult to organise a randomised clinical trial to assess early versus delayed vaccination strategies against RV. Hence, modelling can be interesting to assess different vaccination strategies. Based on literature review and database analysis the occurrence of DE in function of age over time (children Results: BestFit results to replicate the DE over time in children age Conclusion: Modelling techniques allow reliable estimates of the difference in number of RV DE if new interventions are programmed at different time points. In case of rotavirus vaccination different vaccination schedules spread over different time periods may occur. A one month difference in full vaccination protection can be dramatic as we can gain 5% of extra DE avoided with an earlier protection scheme. Given this difference, these results suggest the consequences of this earlier vaccination strategy on cost and QoL of the individual and his direct environment should be assessed.

Introduction: Despite widespread use of annual Pap screening by approx. 5.5 million Canadian wome... more Introduction: Despite widespread use of annual Pap screening by approx. 5.5 million Canadian women, an average of 1408 women are diagnosed with cervical cancer, and 416 die annually. The implementation of a cervical cancer vaccination program is fast approaching; however its long term impact is still unclear. A Monte-Carlo simulation model was used to explore the impact of a cervical cancer vaccine on incidence of invasive cervical cancer (ICC), mortality and life-years gained in Canada. Methods: The analysis was based on ICC incidence (9.2 per 100,000 women) and mortality (2.7 per 100,000 women) from the Canadian Cancer Registry (1990-2001). Other Canadian-specific data required were age-specific population demographics, life-expectancy, mean survival time for fatal ICC cases, and HPV 16/18 prevalence in cervical cancer. Using Microsoft® Excel, the model runs by replicating the latest annual cervical cancer incidence and mortality rate and simulating the HPV-infection rate at younger age subtracting from each cancer case a specific 'time to disease progression' distribution. Vaccination at age 11 (95% vaccine efficacy, 100% coverage, and lifetime duration of vaccine protection) was assessed. One-way sensitivity analyses were conducted to assess parameter uncertainties. Impact of vaccination at various ages were estimated nationally and for each of the 10 provinces. Results: In the base case analysis, vaccination at age 11 reduced ICC cases by 66% (from 1,408 to 474 cases) and related mortality by 66% (from 418 to 140 deaths). Results were similar for vaccination at age 15. The reduction in ICC cases and mortality for vaccination at age 25 was 40% and 53%, respectively. Total life-years gained for vaccinated females was 7,751 years. Similar reductions were observed for all provinces, varying slightly by age of vaccination. The results were sensitive to variation in prevalence of HPV 16/18 among cancer cases, coverage, and age of vaccination. Conclusion: In Canada, vaccinating females with a cervical cancer vaccine would result in substantial reduction in ICC cases and related mortality.

Value in Health, Dec 1, 2022

Value in Health, Oct 1, 2017

Value in Health, Nov 1, 2016

Value in Health, Nov 1, 2014

Human Vaccines & Immunotherapeutics, Apr 29, 2014

Vaccine, Feb 1, 2022

BACKGROUND Observational data on the reduction in hospitalisations after rotavirus vaccine introd... more BACKGROUND Observational data on the reduction in hospitalisations after rotavirus vaccine introduction in Belgium suggest that vaccine impact plateaued at an unexpectedly high residual hospitalisation rate. The objective of this analysis was to identify factors that influence real-world vaccine impact. METHODS Data were collected on hospitalisations in children aged ≤ 5 years with rotavirus disease from 11 hospitals since 2005 (the RotaBIS study). The universal rotavirus vaccination campaign started late in 2006. A mathematical model simulated rotavirus hospitalisations in different age groups using vaccine efficacy and herd effect, influenced by vaccine coverage, vaccine waning, and secondary infection sources. The model used optimisation analysis to fit the simulated curve to the observed data, applying Solver add-in software. It also simulated an 'ideal' vaccine introduction maximising hospitalisation reduction (maximum coverage, maximum herd effect, no waning), and compared this with the best-fit simulated curve. Modifying model input values identified factors with the largest impact on hospitalisations. RESULTS Compared with the 'ideal' simulation, observed data showed a slower decline in hospitalisations and levelled off after three years at a higher residual hospitalisation rate. The slower initial decline was explained by the herd effect in unvaccinated children. The higher residual hospitalisation rate was explained by starting the vaccine programme in November, near the rotavirus seasonal peak. This resulted in low accumulated vaccine coverage during the first rotavirus disease peak season, with the consequential appearance of secondary infection sources. This in turn reduced the herd effect, resulting in a diminished net impact. CONCLUSIONS Our results indicate that countries wishing to maximise the impact of rotavirus vaccination should start vaccinating well ahead of the rotavirus seasonal disease peak. This maximises herd effect during the first year leading to rapid and high reduction in hospitalisations. Secondary infection sources explain the observed data in Belgium better than vaccine waning.

MDM policy & practice, Jul 1, 2019

Transactions of The Royal Society of Tropical Medicine and Hygiene, Nov 1, 1988

In the first seroepidemiological survey in Burundi in 1984, only 59 acquired immunodeficiency syn... more In the first seroepidemiological survey in Burundi in 1984, only 59 acquired immunodeficiency syndrome (AIDS) cases were recognized. We report here clinical surveillance of AIDS cases in the 4 hospitals in Bujumbura during a 4-month period in 1986. The project was combined with a seroprevalence study of pregnant women in the 6 dispensaries in Bujumbura. 258 AIDS patients were recorded. 16% of the 925 pregnant women were seropositive for human immunodeficiency virus (HIV). The clinical characteristics of 120 adult AIDS patients were similar to those reported in Kinshasa or Kigali. From demographic findings we presume that the major mode of HIV transmission in Bujumbura is by sexual contact. The results of this study formed the starting point of prevention activities against AIDS in Burundi.