Nancy Thiry

Economic Evaluations of Varicella Vaccination Programmes

Chickenpox infections are generally mild but due to their very high incidence among healthy children they give rise to considerable morbidity and occasional mortality. With the development of a varicella vaccine in the early 1970s and its progressive licensing in many countries, interest in the efficiency of varicella immunisation programmes grew. The objective of this review was to discuss the methodological aspects and results of published economic evaluations of varicella vaccination. From this, we attempted to make recommendations.A computerised search was carried out; 17 full economic evaluations of varicella vaccination were retrieved. The review identified the methodological divergences and similarities between the articles in four areas: study design, epidemiological data, economic data and model characteristics. We assessed to what extent the applied methods conform to general guidelines for the economic evaluation of healthcare interventions and compared the studies’ results.The desirability of a universal vaccination programme depends on whose perspective is taken. Despite variability in data and model assumptions, the studies suggest that universal vaccination of infants is attractive to society because large savings occur from averted unproductive days for parents. For the healthcare payer, universal vaccination of infants does not generate savings. Vaccination of susceptible adolescents has been proposed by some authors as a viable alternative; the attractiveness of this is highly dependent on the negative predictive value of anamnestic screening. Targeted vaccination of healthcare workers and immunocompromised individuals appears relatively cost effective. Findings for other target groups are either contradictory or provide insufficient evidence for any unequivocal recommendations to be made. High sensitivity to vaccine price was reported in most studies.This review highlights that some aspects of these studies need to be further improved before final recommendations can be made. First, more transparency, completeness and compliance to general methodological guidelines are required. Second, because of the increasing severity of varicella with age, it is preferable and in some cases essential to use dynamic models for the assessment of universal vaccination strategies. Third, most studies focused on the strategy of vaccinating children only while their results depended heavily on disputable assumptions (regarding vaccine effectiveness and impact on herpes zoster). Since violation of these assumptions could have important adverse public health effects, we suggest pre-adolescent vaccination as a more secure alternative. This option deserves more attention in future analyses.

The seroepidemiology of primary varicella-zoster virus infection in Flanders (Belgium)

Abstract. The age-specific seroprevalence of varicella-zoster virus (VZV) antibodies was assessed in a sample of the Flemish (Belgian) population. ELISA tests were used to analyse 1673 sera from subjects aged 1 to 44 years (October 1999 – April 2000). Chickenpox infections in Flanders appear to affect children at a younger age than in other European countries since 47.37% (95% CI: 37.33–57.41) is already immune at 2 years of age. For older age-groups, the prevalence is similar to that of most European countries: 80.19% (95% CI: 72.60–87.78) at 5 years, 92.52% (95% CI: 87.54–97.51) at 9 years and 100%≥40 years. The accuracy of non-positive recollections of varicella histories among Flemish 10 to 17-year olds was examined on the basis of a second (residual) serum bank. In this group, VZV seroprevalence was almost always 100% (or nearly 100%), irrespective of age, degree of reliability (negative or uncertain answers) or level of ascertainment (child personally or parents). The limited size of this second data set did not allow for an accurate assessment of the negative predictive value of such recollections. Conclusion: since varicella-zoster virus predominantly affects very small children and is generally perceived as benign, the required high coverage rate of a universal childhood varicella vaccination programme may be hard to attain. Adolescent strategies can minimise the population risks involved but the accuracy of non positive antecedents of chickenpox needs to be documented to assess the efficiency of such strategies.

Varicella vaccination in Europe: are we ready for a universal childhood programme?

Safe and effective vaccines against varicella zoster virus (VZV), the aetiological agent of varicella and shingles, have been available in Europe for the last 5–10xa0years. The USA has had a universal childhood vaccination policy since 1995 and this has resulted in a dramatic decrease in the incidence, morbidity and mortality related to varicella. The economic and medical burden of VZV has led to discussions regarding both the desirability and feasability of a similar routine immunisation policy for all European children. This article examines the epidemiology of varicella in Europe and how the data emerging from the USA can be used to achieve adequate prevention of the disease. It looks into the current evidence of the health economic evaluation of universal varicella vaccination and explores the concerns surrounding such a policy, including the postulated impact on the incidence of zoster. In conclusion, the Society of Independent European Vaccination Experts (SIEVE) recommends that the immunisation of susceptible adolescents needs to be urgently implemented, in addition to the current recommendations targeting high-risk patients, their close contacts with a negative history of varicella and seronegative health-care workers. A universal policy, optimally incorporating a two-dose schedule, will be needed to finally reduce the burden of disease of varicella from a societal point of view. The SIEVE recommends the implementation of such a policy as soon as financially and practically possible.

RECOMMENDATIONS FOR THE USE OF THE 23-VALENT POLYSACCHARIDE PNEUMOCOCCAL VACCINE IN ADULTS: A BELGIAN CONSENSUS REPORT.

Abstract A multidisciplinary expert panel, appointed by the High Council for Public Health, evaluated the scientific evidence on which the recommendations for the appropriate use of the pneumococcal vaccine was based and reviewed the studies that became available since previous reports. The conclusions of the working group, presented in this manuscript, resulted in an update of the Belgian recommendations for pneumococcal vaccination.

ECONOMIC EVALUATIONS OF PNEUMOCOCCAL VACCINATION STRATEGIES IN ADULTS. A SUMMARY OF THE RESULTS.

Abstract With the view to re-evaluate the current evidence about the efficiency of adult pneumococcal vaccination, we searched the Medline database to collect recent full economic evaluations on this topic. We included a literature review based on studies published up to June 2001 and 5 other studies published between July 2001 and April 2004. Based on these articles’ results, pneumococcal vaccination of the elderly aged between 65 and 75 years is found to be relatively cost-effective for the health care payer. There is also evidence that vaccination of HIV+ patients and of young military personnel may be justifiable on the basis of economic evaluation including direct medical costs only. Conclusions about universal vaccination of younger adults (< 65 years) and of high-risk groups could not be drawn because of controversial results. An accurate assessment of the efficiency of adult pneumococcal vaccination is however hard to achieve given the difficulties in collecting valid input data (e.g. for the incidence and mortality of the disease) and given the remaining uncertainties about the vaccine efficacy for non-invasive disease. Finally, by lack of data, none of the studies estimated the impact of vaccination on antimicrobial resistance.

Economic Evaluation of Varicella Vaccination Programmes: A Review of the Literature. The Authors' Reply

The article explains that if decision makers are willing to adopt the recommended societal perspective, universal infant varicella vaccination is very desirable since large savings are expected to occur in all economic evaluations adopting this perspective. By contrast, if decision makers do not wish to consider the time lost by parents or caregivers and prefer to adopt the more narrow healthcare payers perspective, then, the results of the studies taking such a perspective all indicate that universal infant varicella vaccination results in high net costs, whilst showing a low efficiency in saving life-years and averting deaths, in comparison with other programmes.

Economic evaluation of pneumococcal vaccines for adults aged over 50 years in Belgium

ABSTRACT Streptococcus pneumoniae causes a high disease burden including pneumonia, meningitis and septicemia. Both a polysaccharide vaccine targeting 23 serotypes (PPV23) and a 13-valent conjugate vaccine (PCV13) are indicated for persons aged over 50 years. We developed and parameterized a static multi-cohort model to estimate the incremental cost-effectiveness and budget-impact of these vaccines at different uptake levels. Using three different vaccine efficacy scenarios regarding non-invasive pneumococcal pneumonia and extensive uni- and multivariate sensitivity analyses, we found a strong preference for PPV23 over PCV13 in all age groups at willingness to pay levels below €300 000 per quality adjusted life year (QALY). PPV23 vaccination would cost on average about €83 000, €60 000 and €52 000 per QALY gained in 50–64, 65–74 and 75–84 year olds, whereas for PCV13 this is about €171 000, €201 000 and €338 000, respectively. Strategies combining PPV23 and PCV13 vaccines were most effective but generally less cost-effective. When assuming a combination of increased duration of PCV13 protection, increased disease burden preventable by PCV13 and a 75% reduction of the PCV13 price, PCV13 could become more attractive in <75 year olds, but would remain less attractive than PPV23 from age 75 years onwards. These observations are independent of the assumption that PPV23 has 0% efficacy against non-invasive pneumococcal pneumonia. Pneumococcal vaccination would be most cost-effective in Belgium, when achieving high uptake with PPV23 in 75–84 year olds, as well as by negotiating a lower market-conform PPV23 price to improve uptake and cost-effectiveness.