Measles resurgence in Brazil: analysis of the 2019 epidemic in the state of São Paulo

Challenges for Sustaining Measles Elimination: Post-Verification Large-Scale Import-Related Measles Outbreaks in Mongolia and Cambodia, Resulting in the Loss of Measles Elimination Status

The Western Pacific Region's pursuit of measles elimination has seen significant progress and setbacks. Mongolia and Cambodia were the first two middle-income countries in the Western Pacific to be verified as having eliminated measles by the Western Pacific Regional Verification Commission for Measles and Rubella Elimination, in March 2014 and 2015, respectively. However, both countries experienced large-scale or prolonged importation-related measles outbreaks shortly afterwards, leading to the re-establishment of endemic transmission. We describe the path to initial elimination in both countries and explore these outbreaks' characteristics, factors contributing to the loss of elimination status, and implications for broader elimination efforts. Data sources include case-based epidemiological and laboratory surveillance reports, historical immunization coverage, genotype data, and published reports of in-depth outbreak investigations. In Mongolia, a single prolonged and large-scale outbreak revealed a hidden immunity gap among young adults and was driven in part by nosocomial transmission, leading to significant morbidity and mortality and loss of elimination status. Cambodia suffered multiple importations from neighboring endemic countries during the global measles resurgence in 2018-2019, complicated by cross-border mobility and significant nosocomial amplification, and the country was ultimately unable to sufficiently distinguish independent chains of transmission, leading to loss of elimination status. Our findings highlight the importance of broadening population immunity assessments beyond children to include adults and specific high-risk groups. Robust routine immunization programs, supplemented by tailored SIAs, are crucial for preventing and managing outbreaks. Additionally, strong outbreak preparedness plans, rapid response strategies, and cross-border collaboration and the global effort to prevent multiple resurgences and large-scale importation-induced outbreaks are vital for maintaining elimination status. The experiences of Mongolia and Cambodia underscore the challenges of sustaining measles elimination in the face of importation risks, shared borders with endemic countries, healthcare system gaps, and population movements. Strengthening the global coordination and synchronization of measles elimination activities is imperative to protect the gains achieved and prevent future setbacks.

Neutralizing antibody titers against D8 genotype and persistence of measles humoral and cell-mediated immunity eight years after the first dose of measles, mumps, and rubella vaccine in Brazilian children

OBJECTIVE

Assess the level of measles vaccine-induced neutralizing antibodies against the D8 genotype and the persistence of humoral and cell-mediated immunity in children who received their first dose of the measles, mumps, and rubella vaccine eight years previously.

METHODS

Measles-specific IgG and neutralizing antibodies were determined in serum using ELISA and plaque reduction neutralization test, respectively. Cellular response was evaluated from peripheral blood mononuclear cells (PBMC). IFN-γ-secreting cells, memory B and T cells, and immunological mediators were assayed by ELISpot, flow cytometry, and multiplex liquid microarray assay, respectively.

RESULTS

Antibody concentrations declined over time; however, the vaccine-induced neutralizing antibodies' effect against D8 and vaccinal genotypes persisted. PBMC stimulated with the vaccine virus exhibited specific IFN- γ-measles-secreting responses in most participants. Participants with high levels of neutralizing antibodies showed a higher proportion of activated B cells compared to participants with low levels of neutralizing antibodies, while proportions of memory CD4+ and CD8+ T cells were similar between these groups. PBMC supernatant cytokine levels showed a significant difference between stimulated and non-stimulated conditions for IL-2, TNF-α, IL-10, and CXCL10.

CONCLUSION

Despite the decline in antibody concentrations over time, the participants still demonstrated neutralizing capacity against the measles D8 genotype five to eight years after the second dose of the measles, mumps, and rubella vaccine. Additionally, most of the enrolled children exhibited cell-mediated immunity responses to measles virus stimulation.

Descriptive Analysis of Measles Outbreak in Liberia, 2022

Background

Liberia reported a large outbreak of measles involving all the counties in 2022. We conducted a descriptive analysis of the measles surveillance data to understand the trend of the outbreak and guide further policy action to prevent future outbreaks.

Methods

We analyzed the measles surveillance data from Epi week 1 to 51, 2022. All the laboratory-confirmed cases, clinically compatible and epidemiologically linked cases were included in the analysis, the variables of interest included the patient's age, sex, place of residence, measles classification, measles vaccination status, and outcome. We cleaned and analyzed the data using R version 4.2.0 and Arc GIS Pro. The demographic characteristics of the cases were presented, the progression of the cases was presented in Epicurve and the spatial distribution and the case fatality rate (CFR) of the case were presented at the district level using the Arc GIS Pro.

Results

The median age of the cases was 4 years (interquartile range: 2-8 years). Children under five years of age constituted 60% of the cases (4836/8127), and females accounted for 52% (4204/8127) of the cases. Only 1% (84/8127) of the cases had documentary evidence of receiving at least one dose of measles-containing vaccine (MCV). Only 3 out of 92 health districts in the country did not report a case of measles during the period under review. The overall cases fatality rate was 1% however CFR of up to 10% were reported in some districts.

Conclusion

The outbreak of measles involved almost all the districts of the country, exposing a possible nationwide suboptimal immunization coverage for MCV. The high CFR reported in some districts needs further investigation.

[Stratification of risk areas for measles transmission: a systematic reviewEstratificación de las zonas de riesgo de transmisión del sarampión: revisión sistemática]

Objective

To perform a systematic review of scientific publications addressing the use of stratification methods to define risk areas for measles transmission.

Method

Articles published in English, Portuguese, and Spanish in journals indexed in the SciELO, PubMed, and LILACS databases were selected. The search terms risk assessment AND measles were used without date limits. Editorials, opinion articles, individual-level observational studies, and publications that did not focus on the application of methods to stratify measles transmission risk areas were excluded. Year of publication, authorship, country where the study was performed, objective, geographic level of analysis, method used, indicators, and limitations were recorded in a data form.

Results

Thirteen articles published between 2011 and 2022 in nine countries from the six World Health Organization (WHO) regions were selected. Of these, 10 referred to the Measles Risk Assessment Tool developed by the WHO/Centers for Disease Control and Prevention. Only one study adapted the tool to the local context. The risk stratification indicators used in the selected studies focused on a combination of the following dimensions: population immunity, quality of surveillance systems, and epidemiologic status. The systematic output of data with adequate quality and coverage was a noteworthy aspect hindering risk stratification.

Conclusion

There seems to be limited dissemination of measles risk stratification strategies, especially at local levels. The need to train human resources to process and interpret risk analyses as part of the routine of surveillance services is emphasized.

The pervasive association between political ideology and COVID-19 vaccine uptake in Brazil: an ecologic study

BACKGROUND

Despite the unequivocal benefits of vaccination, vaccine coverage has been falling in several countries in the past few years. Studies suggest that vaccine hesitancy is an increasingly significant phenomenon affecting adherence to vaccines. More recently, during the COVID-19 pandemic, political views have emerged as an additional influencing factor for vaccine hesitancy.

METHODS

In this ecologic study, we used information from publicly available databases to investigate the association between political ideology, depicted by the percentage of votes for the right-wing candidate Jair Bolsonaro in the presidential elections of 2018 and 2022, and COVID-19 vaccination in Brazilian municipalities. The primary endpoint was the COVID-19 vaccination index, calculated as the number of COVID-19 vaccine doses administered up to September 2022 divided by the number of inhabitants in each municipality. The analysis was conducted using Pearson correlation coefficients and linear regression models adjusted for HDI, the percentage of male voters, the percentage of voters who were older than 50 years old, and the percentage of voters with a middle school education or less. In addition, we explored whether the effect of the percentage of Bolsonaro voters on the COVID-19 vaccination index was modified in different quartiles of HDI using an interaction term.

RESULTS

Five thousand five hundred sixty-three Brazilian municipalities were included in the analysis. For both the 2018 and 2022 elections, the percentage of votes for Jair Bolsonaro was significantly and inversely associated with COVID-19 vaccine uptake after adjustment for the sociodemographic characteristics of the voters (change in mean vaccination index in 2018 for each 1% increase in Bolsonaro voters -0.11, 95% confidence interval [CI] -0.13 to -0.08, p < 0.001; change in mean vaccination index in 2022 for each 1% increase in Bolsonaro voters -0.09, 95% CI -0.11 to -0.07, p < 0.001). We also found a statistically significant interaction between the primary predictor of interest and HDI scores, with a more significantly detrimental effect of the right-wing political stance in municipalities in the lower HDI quartiles (interaction p < 0.001 for the first HDI quartile; p = 0.001 for the second HDI quartile).

CONCLUSION

Our findings suggest that political ideologies have influenced COVID-19 vaccine hesitancy in Brazilian municipalities, affecting communities inequitably. The politicization of vaccines is a new challenge for vaccine programs. Strategies to face these challenges should include joint efforts from governments and civil society for a common public health goal.

Reduced Prevalence of Measles Antibodies in a Cohort of Brazilian Children under 15 Years of Age

Measles is a highly contagious acute febrile disease responsible for sporadic but explosive outbreaks worldwide. Although it was considered eliminated from the Americas, the disease reemerged in 2017. This reemergence was linked to reduced immunization rates. Vaccination, early identification of cases, and blocking of the transmission chain are the most effective tools to combat measles, for which there is not a specific antiviral treatment. In this Brazilian prospective cross-sectional study, we investigated the prevalence of measles antibodies in children, a population vulnerable to significant morbidity and mortality from exposure to infection. Between December 2018 to November 2019, blood samples from 252 children were collected and assessed for the presence of measles-specific IgG antibodies and an overall prevalence of 75.8% was observed. We further stratified the cohort into age subgroups, none of which exhibited antibody presence levels above the herd immunity threshold of 94%. Moreover, the calculated number of secondary cases resulting from a case in any age group ranged from 3 to 4, demonstrating that even with partial vaccination coverage this disease is still concerning and highly transmissible. Despite global warnings about measles and previous efforts to combat the advance of the disease, data on antibody prevalence and vaccination coverage in several countries are still concerning and indicate that significant parts of the population could be affected. Seroprevalence studies like this one are important to highlight actual epidemiological conditions and emphasize the need for additional strategies to encourage immunization and avoid the potential impacts of measles, particularly in children who can be severely affected.

Identificação de áreas de risco e fatores associados à epidemia de sarampo de 2019 no Estado de São Paulo, Brasil

O objetivo foi analisar a ocorrência de clusters e fatores associados ao ressurgimento de casos de sarampo da maior epidemia do período pós-eliminação, ocorrida no Estado de São Paulo, Brasil, em 2019. Fatores sociossanitários e assistenciais foram analisados por modelos de Poisson inflacionado de zero (ZIP) e ZIP com efeito espacial estruturado e não estruturado. A estatística de varredura SCAN foi usada para analisar a ocorrência de clusters de casos. Foram identificados clusters de casos de alto risco em municípios que compõem a região intermediária de São Paulo. No modelo ZIP, foram observadas como fatores de risco no nível municipal as variáveis chefes de domicílio menores de 18 anos (RR ajustado = 1,39; ICr95%: 1,27-1,53), desigualdade na distribuição de renda (RR ajustado = 36,67; ICr95%: 26,36-51,15), desocupação em maiores de 18 anos (RR ajustado = 1,10; ICr95%: 1,08-1,12) e iluminação pública inexistente (RR ajustado = 1,05; ICr95%: 1,04-1,05). Nos modelos ZIP com efeito espacial estruturado e não estruturado, foram identificados como fatores de risco os indicadores chefes de domicílio menores de 18 anos (RR ajustado = 1,36; ICr95%: 1,04-1,90) e desigualdade na distribuição dos rendimentos do trabalho (RR ajustado = 3,12; ICr95%: 1,02-9,48). Em ambos os modelos, a cobertura de agentes de saúde se apresentou como fator de proteção. Os achados reforçam a importância de intensificar as ações de vigilância de sarampo articuladas à Estratégia Saúde da Família, especialmente em áreas de maior vulnerabilidade social, para garantir coberturas vacinais equânimes e satisfatórias e reduzir o risco de reemergência da doença.