Adapting response to a measles outbreak in a context of high vaccination and breakthrough cases: an example from Vaud, Switzerland, January to March 2024.

A measles outbreak with 51 cases occurred in the canton of Vaud, Switzerland, between January and March 2024. The outbreak was triggered by an imported case, and 37 (72.5%) subsequent cases were previously vaccinated individuals. Epidemiological investigations showed that vaccinated measles cases were symptomatic and infectious. In a highly vaccinated population, it is important to raise awareness among healthcare professionals to suspect and test for measles virus when an outbreak is declared, irrespective of the vaccination status of the patients.

Measles Vaccine Coverage and Disease Outbreaks: A Systematic Review of the Early Impact of COVID-19 in Low and Lower-Middle Income Countries.

Objectives: We aimed to evaluate changes to measles-containing vaccine (MCV) provision and subsequent measles disease cases in low- and lower-middle income countries (LICs, LMICs) in relation to the COVID-19 pandemic. Methods: A systematic search was conducted of MEDLINE, OVID EMBASE and PubMed records. Primary quantitative and qualitative research studies published from January 2020 were included if they reported on COVID-19 impact on MCV provision and/or measles outbreak rates within LICs and LMICs. Results: 45 studies were included. The change in MCV1 vaccination coverage in national and international regions ranged -13% to +44.4% from pre-COVID time periods. In local regions, the median MCV1 and overall EPI rate changed by -23.3% and -28.5% respectively. Median MCV2 rate was disproportionally impacted in local areas during COVID-interruption time-periods (-48.2%) with ongoing disruption in early-recovery time-periods (-17.7%). 8.9% of studies reported on vaccination status of confirmed measles cases; from these, 71%-91% had received no MCV dose. Conclusion: MCV vaccination coverage experienced ongoing disruption during the recovery periods after initial COVID-19 disruption. Vaccination in local area datasets notably experienced longer-term disruption compared to nationally reported figures.

[Effects of the vaccination campaign on hospitalization and mortality linked to measles in Brazil in the last decade]. / Efeitos da campanha de vacinação nas internações e mortalidade relacionados ao sarampo no Brasil na última década.

Measles is one of the main causes of morbidity and mortality in the pediatric population and it can be prevented with 100% effectiveness by vaccination. However, the disease remains active in throughout Brazil. The scope of this article is to evaluate the population's adherence to vaccination and the potential connection with hospitalizations and mortality in relation to measles in Brazil. This is an ecological study based on secondary data on mortality and hospitalizations due to measles and vaccination coverage against the disease in Brazil from 2013 to 2022. The peak of adherence to the measles vaccination schedule occurred in the 3 years that preceded the eradication of the disease in the country, which occurred in 2016. In this interval, there are the lowest hospitalization rates, with zero mortality from 2014 to 2017. On the other hand, there has been a marked drop in vaccination rates since 2019, when the disease resurfaced in Brazil. Concomitantly, hospitalization and mortality rates reach the highest recorded values. Population adherence to the complete measles vaccination schedule, which is essential to control the disease and related deaths, is insufficient, which is reflected in hospitalization and mortality rates.

O sarampo é uma das principais causas de morbidade e mortalidade na população pediátrica e pode ser prevenido com 100% de eficácia pela vacinação. No entanto, a doença permanece ativa no território brasileiro. O objetivo do artigo é avaliar a adesão da população à vacinação e a possível relação com hospitalização e mortalidade em relação ao sarampo no Brasil. Trata-se de um estudo ecológico realizado a partir de dados secundários de mortalidade e internações acerca do sarampo e da cobertura vacinal contra a doença no Brasil nos anos de 2013 a 2022. O ápice de adesão ao calendário vacinal contra o sarampo se deu nos três anos que precederam a erradicação da doença no país, ocorrida em 2016. Nesse intervalo, tem-se as menores taxas de internação, com a mortalidade zerada de 2014 a 2017. Em contrapartida, verifica-se, desde então, queda na taxas de vacinação, acentuadas a partir de 2019, quando a doença reaparece no Brasil. Concomitantemente, as taxas de internação e mortalidade atingem os valores mais altos registrados. A adesão populacional ao calendário vacinal completo contra o sarampo, essencial ao controle da doença e dos óbitos relacionados, está insuficiente, o que se reflete nas taxas de internações e mortalidade.

Applying Reverse Genetics to Study Measles Virus Interactions with the Host.

The study of virus-host interactions is essential to achieve a comprehensive understanding of the viral replication process. The commonly used methods are yeast two-hybrid approach and transient expression of a single tagged viral protein in host cells followed by affinity purification of interacting cellular proteins and mass spectrometry analysis (AP-MS). However, by these approaches, virus-host protein-protein interactions are detected in the absence of a real infection, not always correctly compartmentalized, and for the yeast two-hybrid approach performed in a heterologous system. Thus, some of the detected protein-protein interactions may be artificial. Here we describe a new strategy based on recombinant viruses expressing tagged viral proteins to capture both direct and indirect protein partners during the infection (AP-MS in viral context). This way, virus-host protein-protein interacting co-complexes can be purified directly from infected cells for further characterization.

Dual RNA-seq Analysis of Patients' Cells and Viral Genome After Measles Infection.

During the infection of a host cell by an infectious agent, a series of gene expression changes occurs as a consequence of host-pathogen interactions. Unraveling this complex interplay is the key for understanding of microbial virulence and host response pathways, thus providing the basis for new molecular insights into the mechanisms of pathogenesis and the corresponding immune response. Dual RNA sequencing (dual RNA-seq) has been developed to simultaneously determine pathogen and host transcriptomes enabling both differential and coexpression analyses between the two partners as well as genome characterization in the case of RNA viruses. Here, we provide a detailed laboratory protocol and bioinformatics analysis guidelines for dual RNA-seq experiments focusing on - but not restricted to - measles virus (MeV) as a pathogen of interest. The application of dual RNA-seq technologies in MeV-infected patients can potentially provide valuable information on the structure of the viral RNA genome and on cellular innate immune responses and drive the discovery of new targets for antiviral therapy.

Setup of Aerosol Delivery System to Prevent Measles Virus Infection in Nonhuman Primate Model.

Measles virus is one of the most contagious airborne human viruses which keeps causing outbreaks in numerous countries over the world despite the existence of an efficient vaccine. Fusion inhibitory lipopeptides were shown to inhibit viral entry into target cells, and their adequate administration into the respiratory tract may provide a novel preventive approach against airborne infections. Aerosol delivery presents the best administration route to deliver such preventive compounds to the upper and lower respiratory tract. This approach offers a conceptually new strategy to protect the population at risk against infection by respiratory viruses, including measles. It is a noninvasive needle-free approach, which may be used when antiviral protection is required, without any medical assistance. In this chapter, we describe the nebulization approach of lipopeptide compounds in nonhuman primates and the subsequent measles virus challenge.

Culturing Immortalized Human Airway Epithelial Cells at an Air-Liquid Interface for Measles Virus Infection.

Measles virus (MeV) infection of airway surface epithelial cells provides a site for final amplification before being released back into the environment via coughing and sneezing. Multiple cell lines have served as models of polarized epithelia for MeV infection, such as Caco2 cells (intestinal derived human epithelia) or MDCK cells (kidney derived canine epithelia). In this chapter, we describe the materials and air-liquid interface (ALI) culture conditions for maintaining four different cell lines derived from human airway epithelial cells: 16HBE14o-, Calu-3, H358, and NuLi-1. We provide methods for confirming transepithelial electrical resistance (TER) and preparing samples for microscopy as well as expected results from apical or basolateral MeV delivery. Polarized human airway derived cells serve as tissue culture models for investigating targeted questions about how MeV exits a human host. In addition, these methods are generalizable to studies of other respiratory viruses or the biology of ALI airway epithelial cells.

Measles Foci Reduction Neutralization Test (FRNT).

The plaque reduction neutralization test (PRNT) and the enzyme-linked immunosorbent assay (ELISA) are both widely used to assess immunity to infectious diseases such as measles, but they use two different measurement principles: ELISA measures the ability of antibodies to bind to virus components, while the PRNT detects the aptitude of antibodies to prevent the infection of a susceptible cell. As a result, detection of measles virus (MV) neutralizing antibodies is the gold standard for assessing immunity to measles. However, the assay is laborious and requires experience and excellent technical skills. In addition, the result is only available after several days. Therefore, the classical PRNT is not suitable for high-throughput testing. By using an immunocolorimetric assay (ICA) to detect MV-infected cells, the standard PRNT has been developed into a focus reduction neutralization test (FRNT). This assay is faster and has improved specificity. The FRNT described here is extremely useful when immunity to measles virus needs to be assessed in patients with a specific medical condition, such as immunocompromised individuals in whom presumed residual immunity needs to be assessed. The FRNT is not generally recommended for use with large numbers of specimens, such as in a seroprevalence study.

Measles IgG Avidity Assay.

Measles IgG avidity assays determine the overall strength of molecular binding between measles-specific IgG antibodies and measles virus antigens. Avidity results can distinguish recent from distant measles virus infections. Individuals who are immunologically naïve to measles virus develop low-avidity antibodies upon measles virus infection or first-time vaccination. Within 4-6 months, antibodies mature to high avidity. Measles avidity assays are most useful in the context of measles elimination. In such settings, avidity and epidemiological and clinical information are used to classify measles breakthrough infections for control and surveillance purposes and to assist in case confirmation when other laboratory results are inconclusive or nonexistent. We present a highly accurate end-titer measles avidity assay that delivers results based on IgG quality (avidity) that are independent of IgG concentration.

Multiplex Bead Assay for the Serological Surveillance of Measles and Rubella.

There is increasing interest in evaluating antibody responses to multiple antigen targets in a single assay. Immunity to measles and rubella are often evaluated together because immunity is provided through combined vaccines and because routine immunization efforts and surveillance for measles and rubella pathogens are combined in many countries. The multiplex bead assay (MBA) also known as the multiplex immunoassay (MIA) described here combines the measurement of measles- and rubella-specific IgG antibodies in serum quantitatively according to international serum standards and has been successfully utilized in integrated serological surveillance.

Coverage and determinants of second-dose measles vaccination among under-five children in East Africa countries: a systematic review and meta-analysis.

Background: One of the biggest breakthroughs of contemporary medicine is measles vaccination. It is essential for the total elimination of measles. Understanding the magnitude and determinants of effective second-dose measles vaccination coverage is a critical task. Accordingly, we set out to check the best available evidence of the pooled second-dose measles vaccination coverage among under-five children in East Africa. Method: We searched electronic databases such as PubMed, Google Scholar, Cochrane, and others. Two reviewers separately carried out the search of the Joanna Briggs Institute, selection of studies, critical appraisal, and data extraction. A third party was involved in resolving the disagreement among the reviewers. Seven studies included in this study, four from Ethiopia, two from Kenya, and one from Tanzania were cross-sectional and published in English language, with publication dates before 29 November 2023. Articles lacking full-text, the intended outcome, and that are not qualitative studies were excluded from the analysis. The Microsoft Excel checklist was used to extract the data and then exported to STATA 11. In addition, I2, Funnel plots, and Egger's test were employed to measure heterogeneity and detect publication bias, respectively. A random effect model was used. Result: The meta-analysis includes a total sample size of 4,962 children from seven articles. The pooled prevalence of second-dose measles vaccination among under-five children in East Africa was found to be 32.22% [95% CI; (18.82, 45.63)], and the significant factors were as follows: birth order (1.72; OR = 95% CI: 1.32, 2.23), information about measles-containing second-dose vaccine (MCV 2) (7.39; OR = 95% CI: 5.21, 10.50), mother's marital status (1.47; OR = 95% CI: 1.05, 2.07), complete immunization for other vaccines (2.17; OR = 95% CI: 1.49, 3.17), and distance of vaccination site (3.31; OR = 95% CI: 2.42, 4.53). Conclusion: The current study found that pooled prevalence of second-dose measles vaccination coverage among under-five children was still very low. It was also observed that birth order, distance of the vaccination site, complete immunization for other vaccines, mother's marital status, and information about MCV were factors associated with second-dose measles vaccination. These factors imply that there is a need for countries and their partners to act urgently to secure political commitment, expand primary health service and health education, and increase vaccination coverage.

Measles in Poland in 2021. / Odra w Polsce w 2021 roku.

INTRODUCTION: Measles is one of the most contagious childhood diseases, and the behavior also occurs in adults. This is a multi-year vaccination covered by an elimination program coordinated by the World Health Organization (WHO). Elimination of measles in the country is conditional on a 95% incidence of infection with two victims, monitoring the epidemiological situation, registering all suspected cases of measles, and monitoring by the WHO Reference Laboratory. In our country, the Department of Virology of the NIZP PZH-PIB in Warsaw serves as the head of the Department of Virology. OBJECTIVES: The aim of this study was to evaluate epidemiological indicators of measles in Poland in 2021 compared to previous years, taking into account the impact of the COVID-19 pandemic. MATERIAL AND METHODS: The assessment of the epidemiological situation was based on a review of data from the bulletin, "Infectious Diseases and Poisons in Poland in 2021" (5), and the assessment of the immunization status of the population was based on data from the bulletin, "Immunization in Poland in 2021" (6). Classification of cases was made based on the definition used in the 2021 surveillance (7). Data from the epidemiological surveillance system "EpiBase" were also used. RESULTS: In 2021, 13 measles cases were registered in Poland (incidence 0.03 per 100,000), 44.8% less than in 2020 and 80% less than the median in 2014-2018. In 2021, the highest incidence was recorded at 0.32 per 100,000 children aged 0-4 years. 6 patients (46.2%) were hospitalized; no deaths due to measles were reported. 32 suspected measles cases were recorded, with over a hundred cases expected. Vaccination status of children aged 3 with the first dose was 90.8%, and the second dose was given to children at the age of 9. - 84.6%. CONCLUSIONS: Epidemiological indicators of measles in 2021 in Poland compared to 2020 have decreased. A similar trend observed throughout Europe. This is related to the extinguishment of outbreaks that occurred before the pandemic, mainly in 2019.

Real-Time Use of a Dynamic Model To Measure the Impact of Public Health Interventions on Measles Outbreak Size and Duration - Chicago, Illinois, 2024.

Measles is a highly infectious, vaccine-preventable disease that can cause severe illness, hospitalization, and death. A measles outbreak associated with a migrant shelter in Chicago occurred during February-April 2024, in which a total of 57 confirmed cases were identified, including 52 among shelter residents, three among staff members, and two among community members with a known link to the shelter. CDC simulated a measles outbreak among shelter residents using a dynamic disease model, updated in real time as additional cases were identified, to produce outbreak forecasts and assess the impact of public health interventions. As of April 8, the model forecasted a median final outbreak size of 58 cases (IQR = 56-60 cases); model fit and prediction range improved as more case data became available. Counterfactual analysis of different intervention scenarios demonstrated the importance of early deployment of public health interventions in Chicago, with a 69% chance of an outbreak of 100 or more cases had there been no mass vaccination or active case-finding compared with only a 1% chance when those interventions were deployed. This analysis highlights the value of using real-time, dynamic models to aid public health response, set expectations about outbreak size and duration, and quantify the impact of interventions. The model shows that prompt mass vaccination and active case-finding likely substantially reduced the chance of a large (100 or more cases) outbreak in Chicago.

Measles Outbreak Associated with a Migrant Shelter - Chicago, Illinois, February-May 2024.

Measles, a highly contagious respiratory virus with the potential to cause severe complications, hospitalization, and death, was declared eliminated from the United States in 2000; however, with ongoing global transmission, infections in the United States still occur. On March 7, 2024, the Chicago Department of Public Health (CDPH) confirmed a case of measles in a male aged 1 year residing in a temporary shelter for migrants in Chicago. Given the congregate nature of the setting, high transmissibility of measles, and low measles vaccination coverage among shelter residents, measles virus had the potential to spread rapidly among approximately 2,100 presumed exposed shelter residents. CDPH immediately instituted outbreak investigation and response activities in collaboration with state and local health departments, health care facilities, city agencies, and shelters. On March 8, CDPH implemented active case-finding and coordinated a mass vaccination campaign at the affected shelter (shelter A), including vaccinating 882 residents and verifying previous vaccination for 784 residents over 3 days. These activities resulted in 93% measles vaccination coverage (defined as receipt of ≥1 recorded measles vaccine dose) by March 11. By May 13, a total of 57 confirmed measles cases associated with residing in or having contact with persons from shelter A had been reported. Most cases (41; 72%) were among persons who did not have documentation of measles vaccination and were considered unvaccinated. In addition, 16 cases of measles occurred among persons who had received ≥1 measles vaccine dose ≥21 days before first known exposure. This outbreak underscores the need to ensure high vaccination coverage among communities residing in congregate settings.

Immunity against measles, mumps, rubella, and varicella among homeless individuals in Germany - A nationwide multi-center cross-sectional study.

Introduction: Homeless individuals suffer a high burden of vaccine-preventable infectious diseases. Moreover, they are particularly susceptible to adverse infection outcomes with limited access to the health care system. Data on the seroprevalence of measles, mumps, rubella, and varicella within this cohort are missing. Methods: The seroprevalence of measles, mumps, rubella, and varicella was determined within the homeless population in Germany. Predictors of lacking immune protection were determined using multivariable logistic regression analysis. Results: Homeless individuals in Germany (n = 611) showed a seroprevalence of 88.5% (95% CI: 85.8-91.0) for measles, 83.8% (95% CI: 80.6-86.6) for mumps, 86.1% (95% CI: 83.1-88.7) for rubella, and 95.7% (95% CI 93.8-97.2) for varicella. Measles seroprevalences declined from individuals born in 1965 to individuals born in 1993, with seroprevalences not compatible with a 95% threshold in individuals born after 1980. For mumps, seroprevalences declined from individuals born in 1950 to individuals born in 1984. Here, seroprevalences were not compatible with a 92% threshold for individuals born after 1975. Seronegativity for measles, mumps and rubella was associated with age but not with gender or country of origin. Discussion: Herd immunity for measles and mumps is not achieved in this homeless cohort, while there was sufficient immune protection for rubella and varicella. Declining immune protection rates in younger individuals warrant immunization campaigns also targeting marginalized groups such as homeless individuals. Given that herd immunity thresholds are not reached for individuals born after 1980 for measles, and after 1975 for mumps, vaccination campaigns should prioritize individuals within these age groups.

Measles outbreak investigation in Berhet District, North Shewa, Ethiopia.

Introduction: Measles, though usually self-limiting, can have severe consequences influenced by factors such as vaccination and nutrition, notably vitamin A deficiency and malnutrition. Despite progress, contextual changes and implementation issues have hampered efforts, resulting in increased outbreaks and cases of measles. This study seeks to pinpoint outbreak features, risk factors, and strategies for preventing and controlling measles. Methods: A descriptive cross-sectional study and a 1:2 unmatched case-control study design were employed. All 101 suspected measles cases listed on the line-list were included in the descriptive research, with 60 measles patients and 120 controls included in the case-control investigation. Line-list data were cleaned and analyzed using a pivot table in Microsoft Excel 2016. Subsequently, the data were cleaned, entered into Epi Info 7.2, and exported to SPSS 26 for analysis. Results: Twenty cases occurred per 10,000 individuals. Men accounted for 67.3% of cases, with ages ranging from 5 months to 45 years and mean and standard deviations of 9.6 and 7.6, respectively. Age group of 5-14 years comprised 57.4% of cases, followed by 1-4 years with 24.8%. Being unvaccinated against measles showed an adjusted odds ratio (AOR) of 12.06 (95% CI: 3.12-46.52). Travel history to regions with active cases had an AOR of 5.73 (95% CI: 1.78-18.38). Contact with a measles patient showed an AOR of 10.3 (95% CI: 3.48-30.5). Understanding the measles transmission mechanism had an AOR of 0.164 (95% CI: 0.049-0.55), and awareness of the disease's preventability had an AOR of 0.233 (95% CI: 0.67-0.811). All factors were independently associated with the illness. Conclusion: This outbreak affected a broader age range with a high attack rate, mainly in the age group of 5-14-years. Over 35% of cases lacked measles vaccination, indicating low administrative vaccine coverage. Factors contributing to the outbreak include lack of measles vaccination, travel to areas with active disease, contact with cases, and insufficient knowledge of measles transmission and prevention strategies among mothers and caregivers.

Second dose of measles-containing vaccine coverage and associated factors among children aged 24-36 months in Gondar city, Central Gondar, Northwest Ethiopia, 2023.

Background: Measles caused 207,000 deaths worldwide in 2019. Ethiopia ranks among the top 10 countries in the world with the highest number of measles cases. However, the coverage of the second dose of measles-containing vaccine (MCV2) remains low. To increase coverage, the government of Ethiopia launched a nationwide measles vaccination campaign. Despite this intervention, the coverage is still below target, and there is scarce information in the study area. Therefore, this study aimed to assess MCV2 coverage and associated factors among children aged 24-36 months in Gondar city, Central Gondar, Northwest Ethiopia, 2023. Methods: A community-based cross-sectional study was conducted among 621 children aged 24-36 months using a systematic random sampling technique from 25 April to 25 May. A pre-tested, interviewer-administered, and structured questionnaire was used and collected using Kobo Toolbox and then transferred to Stata version 17 for further analysis. The binary logistic regression model was used to identify factors, and the presence of an association was declared using a p-value of <0.05. Similarly, an adjusted odds ratio with a 95% confidence interval was used to interpret the direction and strength of an association. Results: A total of 621 children, with a response rate of 98.1%, participated in the study. The coverage of the second dose of MCV was 75.68% (95% CI: 72.1-78.9). The following factors were significantly associated with measles-containing vaccine second dose (MCV2) coverage: father as the household head (AOR: 3.06, 95% CI: 1.43-6.44), first birth order (AOR: 4.45, 95% CI: 1.21-16.3), four and above antenatal care (ANC) follow-ups (AOR: 5.18, 95% CI:1.62-16.5), postnatal care (PNC) service utilization (AOR: 2.57, 95% CI:1.27-5.15), at least two doses of vitamin A uptake (AOR: 6.39, 95% CI: 2.67-15.2), mothers having high awareness (AOR: 1.97, 95% CI:1.15-3.4), and good perception (AOR: 3.6, 95% CI: 2-6.47) about measles vaccination. Conclusion and recommendations: The coverage of MCV2 in the study area is lower than the national and global target of above 95%. Head of household, birth order, ANC follow-up, PNC service utilization, vitamin A uptake, awareness, and perception of mothers about measles vaccination were significant factors for MCV2 coverage. Creating awareness, increasing the perception of mothers about measles vaccination, and strengthening the ANC and PNC services will increase the coverage.

A measles and rubella vaccine microneedle patch in The Gambia: a phase 1/2, double-blind, double-dummy, randomised, active-controlled, age de-escalation trial.

BACKGROUND: Microneedle patches (MNPs) have been ranked as the highest global priority innovation for overcoming immunisation barriers in low-income and middle-income countries. This trial aimed to provide the first data on the tolerability, safety, and immunogenicity of a measles and rubella vaccine (MRV)-MNP in children. METHODS: This single-centre, phase 1/2, double-blind, double-dummy, randomised, active-controlled, age de-escalation trial was conducted in The Gambia. To be eligible, all participants had to be healthy according to prespecified criteria, aged 18-40 years for the adult cohort, 15-18 months for toddlers, or 9-10 months for infants, and to be available for visits throughout the follow-up period. The three age cohorts were randomly assigned in a 2:1 ratio (adults) or 1:1 ratio (toddlers and infants) to receive either an MRV-MNP (Micron Biomedical, Atlanta, GA, USA) and a placebo (0·9% sodium chloride) subcutaneous injection, or a placebo-MNP and an MRV subcutaneous injection (MRV-SC; Serum Institute of India, Pune, India). Unmasked staff ransomly assigned the participants using an online application, and they prepared visually identical preparations of the MRV-MNP or placebo-MNP and MRV-SC or placebo-SC, but were not involved in collecting endpoint data. Staff administering the study interventions, participants, parents, and study staff assessing trial endpoints were masked to treatment allocation. The safety population consists of all vaccinated participants, and analysis was conducted according to route of MRV administration, irrespective of subsequent protocol deviations. The immunogenicity population consisted of all vaccinated participants who had a baseline and day 42 visit result available, and who had no protocol deviations considered to substantially affect the immunogenicity endpoints. Solicited local and systemic adverse events were collected for 14 days following vaccination. Unsolicited adverse events were collected to day 180. Age de-escalation between cohorts was based on the review of the safety data to day 14 by an independent data monitoring committee. Serum neutralising antibodies to measles and rubella were measured at baseline, day 42, and day 180. Analysis was descriptive and included safety events, seroprotection and seroconversion rates, and geometric mean antibody concentrations. The trial was registered with the Pan African Clinical Trials Registry PACTR202008836432905, and is complete. FINDINGS: Recruitment took place between May 18, 2021, and May 27, 2022. 45 adults, 120 toddlers, and 120 infants were randomly allocated and vaccinated. There were no safety concerns in the first 14 days following vaccination in either adults or toddlers, and age de-escalation proceeded accordingly. In infants, 93% (52/56; 95% CI 83·0-97·2) seroconverted to measles and 100% (58/58; 93·8-100) seroconverted to rubella following MRV-MNP administration, while 90% (52/58; 79·2-95·2) and 100% (59/59; 93·9-100) seroconverted to measles and rubella respectively, following MRV-SC. Induration at the MRV-MNP application site was the most frequent local reaction occurring in 46 (77%) of 60 toddlers and 39 (65%) of 60 infants. Related unsolicited adverse events, most commonly discolouration at the application site, were reported in 35 (58%) of 60 toddlers and 57 (95%) of 60 infants that had received the MRV-MNP. All local reactions were mild. There were no related severe or serious adverse events. INTERPRETATION: The safety and immunogenicity data support the accelerated development of the MRV-MNP. FUNDING: Bill & Melinda Gates Foundation.