Dataset Information

The introduction of 'No jab, No school' policy and the refinement of measles immunisation strategies in high-income countries.

ABSTRACT:

Background

In recent years, we witnessed a resurgence of measles even in countries where, according to WHO guidelines, elimination should have already been achieved. In high-income countries, the raise of anti-vaccination movements and parental vaccine hesitancy are posing major challenges for the achievement and maintenance of high coverage during routine programmes. Italy and France approved new regulations, respectively in 2017 and 2018, aimed at raising immunisation rates among children by introducing mandatory vaccination at school entry.

Methods

We simulated the evolution of measles immunity profiles in seven distinct countries for the period 2018-2050 and evaluated the effect of possible adjustments of immunisation strategies adopted in the past on the overall fraction and age distribution of susceptible individuals in different high-income demographic settings. The proposed model accounts for country-specific demographic components, current immunity gaps and immunisation activities in 2018. Vaccination strategies considered include the enhancement of coverage for routine programmes already in place and the introduction of a compulsory vaccination at primary school entry in countries where universal school enrolment is likely achieved.

Results

Our model shows that, under current vaccination policies, the susceptible fraction of the population would remain below measles elimination threshold only in Singapore and South Korea. In the UK, Ireland, the USA and Australia either the increase of coverage of routine programmes above 95% or the introduction of a compulsory vaccination at school entry with coverage above 40% are needed to maintain susceptible individuals below 7.5% up to 2050. Although the implementation of mandatory vaccination at school entry would be surely beneficial in Italy, strategies targeting adults would also be required to avoid future outbreaks in this country.

Conclusions

Current vaccination policies are not sufficient to achieve and maintain measles elimination in most countries. Strategies targeting unvaccinated children before they enter primary school can remarkably enhance the fulfilment of WHO targets.

SUBMITTER: Trentini F

PROVIDER: S-EPMC6524211 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature

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Publications

The introduction of 'No jab, No school' policy and the refinement of measles immunisation strategies in high-income countries.

Trentini Filippo F Poletti Piero P Melegaro Alessia A Merler Stefano S

BMC medicine 20190517 1

<h4>Background</h4>In recent years, we witnessed a resurgence of measles even in countries where, according to WHO guidelines, elimination should have already been achieved. In high-income countries, the raise of anti-vaccination movements and parental vaccine hesitancy are posing major challenges for the achievement and maintenance of high coverage during routine programmes. Italy and France approved new regulations, respectively in 2017 and 2018, aimed at raising immunisation rates among child ...[more]

PMID: 31096986

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Project description:The current policy of measles vaccination at 9 months of age was decided in the mid-1970s. The policy was not tested for impact on child survival but was based on studies of seroconversion after measles vaccination at different ages. The authors examined the empirical evidence for the six underlying assumptions.Secondary analysis.These assumptions have not been research issues. Hence, the authors examined case reports to assess the empirical evidence for the original assumptions. The authors used existing reviews, and in December 2011, the authors made a PubMed search for relevant papers. The title and abstract of papers in English, French, Portuguese, Spanish, German and Scandinavian languages were assessed to ascertain whether the paper was potentially relevant. Based on cumulative measles incidence figures, the authors calculated how many measles cases had been prevented assuming everybody was vaccinated at a specific age, how many 'vaccine failures' would occur after the age of vaccination and how many cases would occur before the specific age of vaccination. In the combined analyses of several studies, the authors used the Mantel-Haenszel weighted RR stratifying for study or age groups to estimate common trends.African community studies of measles infection.Consistency between assumptions and empirical evidence and the predicted effect on mortality.In retrospect, the major assumptions were based on false premises. First, in the single study examining this point, seronegative vaccinated children had considerable protection against measles infection. Second, in 18 community studies, vaccinated measles cases ('vaccine failures') had threefold lower case death than unvaccinated cases. Third, in 24 community studies, infants had twofold higher case death than older measles cases. Fourth, the only study examining the assumption that 'vaccine failures' lead to lack of confidence found the opposite because vaccinated children had milder measles infection. Fifth, a one-dose policy was recommended. However, the two randomised trials of early two-dose measles vaccination compared with one-dose vaccination found significantly reduced mortality until 3 years of age. Thus, current evidence suggests that the optimal age for a single dose of measles vaccine should have been 6 or 7 months resulting in fewer severe unvaccinated cases among infants but more mild 'vaccine failures' among older children. Furthermore, the two-dose trials indicate that measles vaccine reduces mortality from other causes than measles infection.Many lives may have been lost by not determining the optimal age of measles vaccination. Since seroconversion continues to be the basis for policy, the current recommendation is to increase the age of measles vaccination to 12 months in countries with limited measles transmission. This policy may lead to an increase in child mortality.

Project description:ObjectiveTo support evidence informed decision-making, we systematically examine the effectiveness and cost-effectiveness of community engagement interventions on routine childhood immunisation outcomes in low-income and middle-income countries (LMICs) and identify contextual, design and implementation features associated with effectiveness.DesignMixed-methods systematic review and meta-analysis.Data sources21 databases of academic and grey literature and 12 additional websites were searched in May 2019 and May 2020.Eligibility criteria for selecting studiesWe included experimental and quasi-experimental impact evaluations of community engagement interventions considering outcomes related to routine child immunisation in LMICs. No language, publication type, or date restrictions were imposed.Data extraction and synthesisTwo independent researchers extracted summary data from published reports and appraised quantitative risk of bias using adapted Cochrane tools. Random effects meta-analysis was used to examine effects on the primary outcome, full immunisation coverage.ResultsOur search identified over 43 000 studies and 61 were eligible for analysis. The average pooled effect of community engagement interventions on full immunisation coverage was standardised mean difference 0.14 (95% CI 0.06 to 0.23, I2=94.46). The most common source of risk to the quality of evidence (risk of bias) was outcome reporting bias: most studies used caregiver-reported measures of vaccinations received by a child in the absence or incompleteness of immunisation cards. Reasons consistently cited for intervention success include appropriate intervention design, including building in community engagement features; addressing common contextual barriers of immunisation and leveraging facilitators; and accounting for existing implementation constraints. The median intervention cost per treated child per vaccine dose (excluding the cost of vaccines) to increase absolute immunisation coverage by one percent was US$3.68.ConclusionCommunity engagement interventions are successful in improving outcomes related to routine child immunisation. The findings are robust to exclusion of studies assessed as high risk of bias.

Project description:BackgroundIn the 21st century, increases in immunisation coverage and decreases in under-5 mortality have substantially reduced the global burden of measles mortality. However, the assessment of measles mortality burden is highly dependent on estimates of case-fatality ratios for measles, which can vary according to geography, health systems infrastructure, prevalence of underlying risk factors, and measles endemicity. With imprecise case-fatality ratios, there is continued uncertainty about the burden of measles mortality and the effect of measles vaccination. In this study, we aimed to update the estimations of case-fatality ratios for measles, to develop a prediction model to estimate case-fatality ratios across heterogeneous groupings, and to project future case-fatality ratios for measles up to 2030.MethodsWe did a review of the literature to identify studies examining measles cases and deaths in low-income and middle-income countries in all age groups from 1980 to 2016. We extracted data on case-fatality ratios for measles overall and by age, where possible. We developed and examined several types of generalised linear models and determined the best-fit model according to the Akaike information criterion. We then selected a best-fit model to estimate measles case-fatality ratios from 1990 to 2015 and projected future case-fatality ratios for measles up to 2030.FindingsWe selected 124 peer-reviewed journal articles published between Jan 1, 1980, and Dec 31, 2016, for inclusion in the final review-85 community-based studies and 39 hospital-based studies. We selected a log-linear prediction model, resulting in a mean case-fatality ratio of 2·2% (95% CI 0·7-4·5) in 1990-2015. In community-based settings, the mean case-fatality ratio was 1·5% (0·5-3·1) compared with 2·9% (0·9-6·0) in hospital-based settings. The mean projected case-fatality ratio in 2016-2030 was 1·3% (0·4-3·7).InterpretationCase-fatality ratios for measles have seen substantial declines since the 1990s. Our study provides an updated estimation of case-fatality ratios that could help to refine assessment of the effect on mortality of measles control and elimination programmes.FundingBill & Melinda Gates Foundation.

Dataset Information

The introduction of 'No jab, No school' policy and the refinement of measles immunisation strategies in high-income countries.

Background

Methods

Results

Conclusions

Publications

The introduction of 'No jab, No school' policy and the refinement of measles immunisation strategies in high-income countries.

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