Challenges to Achieving Measles Elimination, Georgia, 2013-2018.
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SUBMITTER: Khetsuriani N
PROVIDER: S-EPMC7588556 | biostudies-literature | 2020 Nov
REPOSITORIES: biostudies-literature
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Challenges to Achieving Measles Elimination, Georgia, 2013-2018.
Khetsuriani Nino N Sanadze Ketevan K Chlikadze Rusudan R Chitadze Nazibrola N Dolakidze Tamar T Komakhidze Tamta T Jabidze Lia L Huseynov Shahin S Ben Mamou Myriam M Muller Claude C Zakhashvili Khatuna K Hübschen Judith M JM
Emerging infectious diseases 20201101 11
Controlling measles outbreaks in the country of Georgia and throughout Europe is crucial for achieving the measles elimination goal for the World Health Organization's European Region. However, large-scale measles outbreaks occurred in Georgia during 2013-2015 and 2017-2018. The epidemiology of these outbreaks indicates widespread circulation and genetic diversity of measles viruses and reveals persistent gaps in population immunity across a wide age range that have not been sufficiently address ...[more]
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Project description:IntroductionIn seven southern African countries (Botswana, Lesotho, Malawi, Namibia, South Africa, Swaziland and Zimbabwe), following implementation of a measles mortality reduction strategy starting in 1996, the number of annually reported measles cases decreased sharply to less than one per million population during 2006-2008. However, during 2009-2010, large outbreaks occurred in these countries. In 2011, a goal for measles elimination by 2020 was set in the World Health Organization (WHO) African Region (AFR). We reviewed the implementation of the measles control strategy and measles epidemiology during the resurgence in the seven southern African countries.MethodsEstimated coverage with routine measles vaccination, supplemental immunization activities (SIA), annually reported measles cases by country, and measles surveillance and laboratory data were analyzed using descriptive analysis.ResultsIn the seven countries, coverage with the routine first dose of measles-containing vaccine (MCV1) decreased from 80% to 65% during 1996-2004, then increased to 84% in 2011; during 1996-2011, 79,696,523 people were reached with measles vaccination during 45 SIAs. Annually reported measles cases decreased from 61,160 cases to 60 cases and measles incidence decreased to <1 case per million during 1996-2008. During 2009-2010, large outbreaks that included cases among older children and adults were reported in all seven countries, starting in South Africa and Namibia in mid-2009 and in the other five countries by early 2010. The measles virus genotype detected was predominantly genotype B3.ConclusionThe measles resurgence highlighted challenges to achieving measles elimination in AFR by 2020. To achieve this goal, high two-dose measles vaccine coverage by strengthening routine immunization systems and conducting timely SIAs targeting expanded age groups, potentially including young adults, and maintaining outbreak preparedness to rapidly respond to outbreaks will be needed.
| S-EPMC10292670 | biostudies-literature
Project description:In 2010, the World Health Assembly (WHA) set the following three milestones for measles control to be achieved by 2015: 1) increase routine coverage with the first dose of measles-containing vaccine (MCV1) among children aged 1 year to ?90% at the national level and to ?80% in every district, 2) reduce global annual measles incidence to less than five cases per 1 million population, and 3) reduce global measles mortality by 95% from the 2000 estimate* (1). In 2012, WHA endorsed the Global Vaccine Action Plan,† with the objective of eliminating measles§ in five of the six World Health Organization (WHO) regions by 2020. This report updates a previous report (2) and describes progress toward WHA milestones and regional measles elimination during 2000-2018. During 2000-2018, estimated MCV1 coverage increased globally from 72% to 86%; annual reported measles incidence decreased 66%, from 145 to 49 cases per 1 million population; and annual estimated measles deaths decreased 73%, from 535,600 to 142,300. During 2000-2018, measles vaccination averted an estimated 23.2 million deaths. However, the number of measles cases in 2018 increased 167% globally compared with 2016, and estimated global measles mortality has increased since 2017. To continue progress toward the regional measles elimination targets, resource commitments are needed to strengthen routine immunization systems, close historical immunity gaps, and improve surveillance. To achieve measles elimination, all communities and countries need coordinated efforts aiming to reach ?95% coverage with 2 doses of measles vaccine (3).
| S-EPMC6897527 | biostudies-literature
Project description:The global measles vaccination program has been extraordinarily successful in reducing measles-related disease and deaths worldwide. Eradication of measles is feasible because of several key attributes, including humans as the only reservoir for the virus, broad access to diagnostic tools that can rapidly detect measles-infectious persons, and availability of highly safe and effective measles-containing vaccines (MCVs). All 6 World Health Organization (WHO) regions have established measles elimination goals. Globally, during 2000-2018, measles incidence decreased by 66% (from 145 to 49 cases per million population) and deaths decreased by 73% (from 535 600 to 142 300), drastically reducing global disease burden. Routine immunization with MCV has been the cornerstone for the control and prevention of measles. Two doses of MCV are 97% effective in preventing measles, qualifying MCV as one of the most effective vaccines ever developed. Mild adverse events occur in <20% of recipients and serious adverse events are extremely rare. The economic benefits of measles vaccination are highlighted by an overall return on investment of 58 times the cost of the vaccine, supply chains, and vaccination. Because measles is one of the most contagious human diseases, maintenance of high (≥95%) 2-dose MCV coverage is crucial for controlling the spread of measles and successfully reaching measles elimination; however, the plateauing of global MCV coverage for nearly a decade and the global measles resurgence during 2018-2019 demonstrate that much work remains. Global commitments to increase community access to and demand for immunizations, strengthen national and regional partnerships for building public health infrastructure, and implement innovations that can overcome access barriers and enhance vaccine confidence, are essential to achieve a world free of measles.
| S-EPMC8482021 | biostudies-literature
Project description:The global measles vaccination program has been extraordinarily successful in reducing measles-related disease and deaths worldwide. Eradication of measles is feasible because of several key attributes, including humans as the only reservoir for the virus, broad access to diagnostic tools that can rapidly detect measles-infectious persons, and availability of highly safe and effective measles-containing vaccines (MCVs). All 6 World Health Organization (WHO) regions have established measles elimination goals. Globally, during 2000-2018, measles incidence decreased by 66% (from 145 to 49 cases per million population) and deaths decreased by 73% (from 535 600 to 142 300), drastically reducing global disease burden. Routine immunization with MCV has been the cornerstone for the control and prevention of measles. Two doses of MCV are 97% effective in preventing measles, qualifying MCV as one of the most effective vaccines ever developed. Mild adverse events occur in <20% of recipients and serious adverse events are extremely rare. The economic benefits of measles vaccination are highlighted by an overall return on investment of 58 times the cost of the vaccine, supply chains, and vaccination. Because measles is one of the most contagious human diseases, maintenance of high (≥95%) 2-dose MCV coverage is crucial for controlling the spread of measles and successfully reaching measles elimination; however, the plateauing of global MCV coverage for nearly a decade and the global measles resurgence during 2018-2019 demonstrate that much work remains. Global commitments to increase community access to and demand for immunizations, strengthen national and regional partnerships for building public health infrastructure, and implement innovations that can overcome access barriers and enhance vaccine confidence, are essential to achieve a world free of measles.
| S-EPMC8482021 | biostudies-literature
Project description:BackgroundVaccination has reduced the global incidence of measles to the lowest rates in history. However, local interruption of measles virus transmission requires sustained high levels of population immunity that can be challenging to achieve and maintain. The herd immunity threshold for measles is typically stipulated at 90-95%. This figure does not easily translate into age-specific immunity levels required to interrupt transmission. Previous estimates of such levels were based on speculative contact patterns based on historical data from high-income countries. The aim of this study was to determine age-specific immunity levels that would ensure elimination of measles when taking into account empirically observed contact patterns.MethodsWe combined estimated immunity levels from serological data in 17 countries with studies of age-specific mixing patterns to derive contact-adjusted immunity levels. We then compared these to case data from the 10 years following the seroprevalence studies to establish a contact-adjusted immunity threshold for elimination. We lastly combined a range of hypothetical immunity profiles with contact data from a wide range of socioeconomic and demographic settings to determine whether they would be sufficient for elimination.ResultsWe found that contact-adjusted immunity levels were able to predict whether countries would experience outbreaks in the decade following the serological studies in about 70% of countries. The corresponding threshold level of contact-adjusted immunity was found to be 93%, corresponding to an average basic reproduction number of approximately 14. Testing different scenarios of immunity with this threshold level using contact studies from around the world, we found that 95% immunity would have to be achieved by the age of five and maintained across older age groups to guarantee elimination. This reflects a greater level of immunity required in 5-9-year-olds than established previously.ConclusionsThe immunity levels we found necessary for measles elimination are higher than previous guidance. The importance of achieving high immunity levels in 5-9-year-olds presents both a challenge and an opportunity. While such high levels can be difficult to achieve, school entry provides an opportunity to ensure sufficient vaccination coverage. Combined with observations of contact patterns, further national and sub-national serological studies could serve to highlight key gaps in immunity that need to be filled in order to achieve national and regional measles elimination.
| S-EPMC6760101 | biostudies-literature
Project description:INTRODUCTION:Despite availability of safe and cost-effective vaccines to prevent it, measles remains one of the significant causes of death among children under five years of age globally. The World Health Organization (WHO) European Region has seen a drastic decline in measles and rubella cases in recent years, and a few of the once common measles genotypes are no longer detected. Buoyed by this success, all Member States of the Region reconfirmed their commitment in 2010 to eliminating measles and rubella, and made this a central objective of the European Vaccine Action Plan 2015-2020 (EVAP). Nevertheless, sporadic outbreaks continue, recently affecting primarily adolescents and young adults with no vaccination or an incomplete vaccination history. The European Regional Verification Commission for Measles and Rubella Elimination was established in 2011 to evaluate the status of measles and rubella elimination based on documentation submitted annually by each country's national verification committee. DISCUSSION:Each country's commitment to eliminate measles and rubella is influenced by competing health priorities, and in some cases lack of capacity and resources. All countries need to improve case-base surveillance for both measles and rubella, ensure documentation of each outbreak and strengthen the link between epidemiology and laboratory data. Achieving high coverage with measles- and rubella-containing vaccines will require a multisectoral approach to address the root causes of lower uptake in identified communities including service delivery challenges or vaccine safety concerns caused by circulating myths about vaccination. CONCLUSIONS:The WHO European Region has made steady progress towards eliminating measles and rubella and over half of the countries interrupted endemic transmission of both diseases by 2015. The programmatic challenges in disease surveillance, vaccination service delivery and communication in the remaining endemic countries should be addressed through periodic evaluation of the strategies by all stakeholders and exploring additional opportunities to accelerate the ongoing elimination activities.
| S-EPMC6524644 | biostudies-literature
Project description:IntroductionMeasles is caused by the highly infectious measles virus, MeV, for which there is an effective vaccine. Monitoring of progress of measles elimination requires enhanced surveillance and tracking of MeV strains, including documenting the absence of an endemically circulating strain. Due to a reduction in the number of circulating genotypes, additional sequence information, beyond the standardized 450 nucleotide window of the nucleoprotein (N450), is required to corroborate the information from epidemiological investigations and, ideally, fill in gaps in the surveillance data.MethodsThis study applies MeV sequencing tools, namely the N450, the non-coding region between the matrix and fusion genes (MF-NCR), and the complete coding sequence of the genome (WGS-t), to clinical specimens obtained from cases occurring over a three-year time period in Canada. This data was systematically analyzed, including with Bayesian evolutionary analysis by sampling trees (BEAST) of the WGS-t.Results and discussionOf the 143 reported cases, N450, MF-NCR, and WGS-t sequences were obtained from 101, 81, and 75 cases, respectively. The BEAST analysis confirmed that the two most frequently detected lineages (B3 named strain MVi/Marikina City.PHL/10.18 and D8 named strain MVs/Gir Somnath.IND/42.16) were the result of repeated importations. Of the 16 outbreaks occurring during the study period, the analysis conclusively corroborated the epidemiological information for 13. BEAST analysis of the WGS-t convincingly demonstrated the expansion of two outbreaks by the inclusion of additional contemporary cases for which the epidemiological investigation had been unable to identify links. Furthermore, the analysis revealed the existence of three additional unrecognized outbreaks among the cases categorized as unknown source. One outbreak was without WGS-t and could not be resolved.ConclusionMeasles WGS-t data corroborated and expanded upon the outbreak analysis from traditional epidemiological investigations of measles outbreaks. However, both are needed for fulsome investigations in elimination settings.
| S-EPMC11611582 | biostudies-literature
Project description:Background:Control efforts for measles and rubella are intensifying globally. It becomes increasingly important to identify and reach remaining susceptible populations as elimination is approached. Methods:Serological surveys for measles and rubella can potentially measure susceptibility directly, but their use remains rare. In this study, using simulations, we outline key subtleties in interpretation associated with the dynamic context of age-specific immunity, highlighting how the patterns of immunity predicted from disease surveillance and vaccination coverage data may be misleading. Results:High-quality representative serosurveys could provide a more accurate assessment of immunity if challenges of conducting, analyzing, and interpreting them are overcome. We frame the core disease control and elimination questions that could be addressed by improved serological tools, discussing challenges and suggesting approaches to increase the feasibility and sustainability of the tool. Conclusions:Accounting for the dynamical context, serosurveys could play a key role in efforts to achieve and sustain elimination.
| S-EPMC6049004 | biostudies-literature
Project description:Although there have been many epidemiological reports of the inter-country transmission of measles, systematic analysis of the global transmission dynamics of the measles virus (MV) is limited. In this study, we applied phylogeographic analysis to characterize the global transmission dynamics of the MV using large-scale genetic sequence data (obtained for 7456 sequences) from 115 countries between 1954 and 2015. These analyses reveal the spatial and temporal characteristics of global transmission of the virus, especially in Australia, China, India, Japan, the UK, and the USA in the period since 1990. The transmission is frequently observed, not only within the same region but also among distant and frequently visited areas. Frequencies of export from measles-endemic countries, such as China, India, and Japan are high but decreasing, while the frequencies from countries where measles is no longer endemic, such as Australia, the UK, and the USA, are low but slightly increasing. The world is heading toward measles eradication, but the disease is still transmitted regionally and globally. Our analysis reveals that countries wherein measles is endemic and those having eliminated the disease (apart from occasional outbreaks) both remain a source of global transmission in this measles elimination era. It is therefore crucial to maintain vigilance in efforts to monitor and eradicate measles globally.
| S-EPMC5408688 | biostudies-literature
Project description: Not available
| S-EPMC10971764 | biostudies-literature