Risk Of Measles Research Articles

Estimating the risk and spatial spread of measles in populations with high MMR uptake: Using school-household networks to understand the 2013 to 2014 outbreak in the Netherlands.

Measles outbreaks are still routine, even in countries where vaccination coverage exceeds the guideline of 95%. Therefore, achieving ambitions for measles eradication will require understanding of how unvaccinated children interact with others who are unvaccinated. It is well established that schools and homes are key settings for both clustering of unvaccinated children and for transmission of infection. In this study, we evaluate the potential for contacts between unvaccinated children in these contexts to facilitate measles outbreaks with a focus on the Netherlands, where large outbreaks have been observed periodically since the introduction of mumps, measles and rubella (MMR). We created a network of all primary and secondary schools in the Netherlands based on the total number of household pairs between each school. A household pair are siblings from the same household who attend a different school. We parameterised the network with individual level administrative school and household data provided by the Dutch Ministry for Education and estimates of school level uptake of the MMR vaccine. We analysed the network to establish the relative strength of contact between schools and found that schools associated with low vaccine uptake are highly connected, aided by a differentiated school system in the Netherlands (Coleman homophily index (CHI) = 0.63). We simulated measles outbreaks on the network and evaluated the model against empirical measles data per postcode area from a large outbreak in 2013 (2,766 cases). We found that the network-based model could reproduce the observed size and spatial distribution of the historic outbreak much more clearly than the alternative models, with a case weighted receiver operating characteristic (ROC) sensitivity of 0.94, compared to 0.17 and 0.26 for models that do not account for specific network structure or school-level vaccine uptake, respectively. The key limitation of our framework is that it neglects transmission routes outside of school and household contexts. Our framework indicates that clustering of unvaccinated children in primary schools connected by unvaccinated children in related secondary schools lead to large, connected clusters of unvaccinated children. Using our approach, we could explain historical outbreaks on a spatial level. Our framework could be further developed to aid future outbreak response.

Assessing measles risk transmission in Iran: a utilization of the World Health Organization’s programmatic risk assessment tool,2022

BackgroundDespite successful efforts to eliminate measles in Iran, imported measles cases continue to be reported. Because measles is endemic in neighboring countries. This research aims to evaluate the risk of measles transmission in different regions of Iran.MethodsMeasles case-based surveillance data of the Expanded Program of Immunization containing 31 provinces and 463 districts from 2019 to 2021 were assessed. The WHO Measles Programmatic Risk Assessment tool was used to evaluate the risk of disease transmission in four domains: population immunity, surveillance quality, program delivery performance, and threat assessment. scores were categorized as low, medium, high, or very high risk.ResultsDuring 2019–2021, the average incidence of measles was 1.9 per 1 million. Chabahar and Mashhad with 76 and ./6per million reported the highest and lowest incidence respectively. All 463 districts were categorized as low risk in risk assessment. Andimeshk, Chabahar, and Bojnurd obtained the highest risk scores with 27, 24, and 25 respectively. All districts were classified as low risk for population immunity. The average coverage of (MMR1) and (MMR2) was 95% or higher. All districts received the minimum points for surveillance quality.ConclusionAll regions are placed at a low level of disease transmission risk. However, the tool is not able to assess the risk at the rural or peripheral sectors level. The indicators used in this tool are the same for all countries with different epidemiological features (elimination, endemic). Sensitivity analysis can optimize the use of this tool for countries with different disease conditions.

Onward Virus Transmission after Measles Secondary Vaccination Failure.

Measles in persons with secondary vaccination failure (SVF) may be less infectious than cases in unvaccinated persons. Our systematic review aimed to assess transmission risk for measles after SVF. We searched PubMed, Embase, and Web of Science databases from their inception dates. Inclusion criteria were articles describing persons who were exposed to measles-infected persons who had experienced SVF. Across the included 14 studies, >3,030 persons were exposed to measles virus from SVF cases, of whom 180 were susceptible, indicating secondary attack rates of 0%-6.25%. We identified 109 cases of SVF from the studies; 10.09% (n = 11) of case-patients transmitted the virus, resulting in 23 further cases and yielding an effective reproduction number of 0.063 (95% CI 0.0-0.5). These findings suggest a remarkably low attack rate for SVF measles cases, suggesting that, In outbreak situations, public health management of unvaccinated persons could be prioritized over persons with SVF.

Modeling the Cost of Vaccinating a Measles Zero-Dose Child in Zambia Using Three Vaccination Strategies.

Countries with moderate to high measles-containing vaccine coverage face challenges in reaching the remaining measles zero-dose children. There is growing interest in targeted vaccination activities to reach these children. We developed a framework for prioritizing districts for targeted measles and rubella supplementary immunization activities (SIAs) for Zambia in 2020, incorporating the use of the WHO's Measles Risk Assessment Tool (MRAT) and serosurveys. This framework was used to build a model comparing the cost of vaccinating one zero-dose child under three vaccination scenarios: standard nationwide SIA, targeted subnational SIA informed by MRAT, and targeted subnational SIA informed by both MRAT and measles seroprevalence data. In the last scenario, measles seroprevalence data are acquired via either a community-based serosurvey, residual blood samples from health facilities, or community-based IgG point-of-contact rapid diagnostic testing. The deterministic model found that the standard nationwide SIA is the least cost-efficient strategy at 13.75 USD per zero-dose child vaccinated. Targeted SIA informed by MRAT was the most cost-efficient at 7.63 USD per zero-dose child, assuming that routine immunization is just as effective as subnational SIA in reaching zero-dose children. Under similar conditions, a targeted subnational SIA informed by both MRAT and seroprevalence data resulted in 8.17-8.35 USD per zero-dose child vaccinated, suggesting that use of seroprevalence to inform SIA planning may not be as cost prohibitive as previously thought. Further refinement to the decision framework incorporating additional data may yield strategies to better target the zero-dose population in a financially feasible manner.

Evaluation of Vulnerable age Group of Measles and its Outcome in Under Five Children

Background: Measles continues to be a major public health problem worldwide, with a high mortality and morbidity. Unvaccinated young children are at highest risk of measles and its complication including death. Objectives: To assess the vulnerable age group of children for measles under five years of age and also to evaluate the demographic profile, common clinical complication, seasonal variation and outcome of measles among children of Bangladesh. Materials and Methods: This Retrospective observational study was done in the Infectious disease’s hospital, Dhaka during the period of July 2018 to June 2019.The data, were collected, compiled and analyzed. Result: During the study period, a total of 74 confirmed measles cases were selected. Among them, 0-<6-month age group were 21.62%, 6 months to <9 months were 40.54%, 9 months to <15 months were 9.46% and 15 months to <60 months were 28.38%. Highest number of measles cases were admitted in February (14.9%), March (16.2%) and April (14.9%) which are mainly the spring and early summer and lowest in winter. Most common complications of measles were pneumonia and diarrhea. Conclusion: Children below nine month of age who did not reach the vaccination age were found most vulnerable for measles. Occurrence of measles found predominantly in spring and early summer. Pneumonia and diarrhea are the common complications. BANGLADESH J CHILD HEALTH 2022; VOL 46 (2) : 76-81

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

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

Seroprevalence of Anti-Measles Immunoglobulin G in Pregnant Women Followed at Laquintinie Hospital and General Hospital of Douala

Introduction: Pregnant women who have been in contact with the measles virus or vaccinated against this virus produce anti-measles antibodies of the IgG type. These will be transferred to the fetus via the placenta to protect it at birth before the vaccination age of 9 months. To this end, we set out to research the titer of anti-measles antibodies and the factors associated with this titer in pregnant women. Methodology: We conducted a cross-sectional study with analytical purposes, from June 2021 to February 2022(9 mois). The recruitment of participants took place in the maternity departments of Laquintinie Hospital and the General Hospital of Douala. Any pregnant woman consultant who had consulted in one of these two hospitals was included in this study. Consecutive sampling was adopted and a technical sheet was used to collect socio-demographic data and obstetric history of the participants. To study the antibody titer, a 5ml sample of venous blood was taken. The qualitative and quantitative investigation of immunoglobulin G in serum was carried out using the “Measles Virus IgG TM ” ELISA (IBM international). The protection titer was considered based on values ≥ 200 mIU/ml. The data collected were analyzed using Excel 2013 and SPSS 20 software and then the associated factors were searched using the odds ratio and the p-value. Results: A total of 160 pregnant women were recruited, the majority age group was 25-30 years old. The participants' histories showed that 16.85% had “had measles” and 1.25% had been in contact with infected children. The biological analysis showed that the titer of anti-measles antibodies was between 40 and 5,000 mIU/ml with a predominance of titer between 200 and 1000 mIU/ml. The status between the neutralizing antibody titer and the protective situation presented 78.13% of women who had a protective level (values ≥ 200 mIU/ml). We observed no significant association between protection status and any factors. Conclusion: A significant fraction of our study population presented an antibody titer lower than the protective level and could therefore not promote sufficient newborn birth in the prevaccination period, thus leaving a possibility of risk of neonatal measles.

Health system barriers to timely routine measles vaccinations in rural southwest China: a qualitative study on the perspectives of township vaccination professionals and village doctors

ObjectivesA well-functioning health system ensures timely routine measles vaccinations for age-appropriate children, minimising measles risk. However, there is limited knowledge about the impact of the performance of immunisation programmes in...

Estimation of the relationship between meteorological factors and measles using spatiotemporal Bayesian model in Shandong Province, China

BackgroundMeasles-containing vaccine (MCV) has been effective in controlling the spread of measles. Some countries have declared measles elimination. But recently years, the number of cases worldwide has increased, posing a challenge to the global goal of measles eradication. This study estimated the relationship between meteorological factors and measles using spatiotemporal Bayesian model, aiming to provide scientific evidence for public health policy to eliminate measles.MethodsDescriptive statistical analysis was performed on monthly data of measles and meteorological variables in 136 counties of Shandong Province from 2009 to 2017. Spatiotemporal Bayesian model was used to estimate the effects of meteorological factors on measles, and to evaluate measles risk areas at county level. Case population was divided into multiple subgroups according to gender, age and occupation. The effects of meteorological factors on measles in subgroups were compared.ResultsSpecific meteorological conditions increased the risk of measles, including lower relative humidity, temperature, and atmospheric pressure; higher wind velocity, sunshine duration, and diurnal temperature variation. Taking lowest value (Q1) as reference, RR (95%CI) for higher temperatures (Q2–Q4) were 0.79 (0.69–0.91), 0.54 (0.44–0.65), and 0.48 (0.38–0.61), respectively; RR (95%CI) for higher relative humidity (Q2–Q4) were 0.76 (0.66–0.88), 0.56 (0.47–0.67), and 0.49 (0.38–0.63), respectively; RR (95%CI) for higher wind velocity (Q2–Q4) were 1.43 (1.25–1.64), 1.85 (1.57–2.18), 2.00 (1.59–2.52), respectively. 22 medium-to-high risk counties were identified, mainly in northwestern, southwestern and central Shandong Province. The trend was basically same in the effects of meteorological factors on measles in subgroups, but the magnitude of the effects was different.ConclusionsMeteorological factors have an important impact on measles. It is crucial to integrate these factors into public health policies for measles prevention and control in China.

Predicting Measles Outbreaks in the United States: Evaluation of Machine Learning Approaches.

Measles, a highly contagious viral infection, is resurging in the United States, driven by international importation and declining domestic vaccination coverage. Despite this resurgence, measles outbreaks are still rare events that are difficult to predict. Improved methods to predict outbreaks at the county level would facilitate the optimal allocation of public health resources. We aimed to validate and compare extreme gradient boosting (XGBoost) and logistic regression, 2 supervised learning approaches, to predict the US counties most likely to experience measles cases. We also aimed to assess the performance of hybrid versions of these models that incorporated additional predictors generated by 2 clustering algorithms, hierarchical density-based spatial clustering of applications with noise (HDBSCAN) and unsupervised random forest (uRF). We constructed a supervised machine learning model based on XGBoost and unsupervised models based on HDBSCAN and uRF. The unsupervised models were used to investigate clustering patterns among counties with measles outbreaks; these clustering data were also incorporated into hybrid XGBoost models as additional input variables. The machine learning models were then compared to logistic regression models with and without input from the unsupervised models. Both HDBSCAN and uRF identified clusters that included a high percentage of counties with measles outbreaks. XGBoost and XGBoost hybrid models outperformed logistic regression and logistic regression hybrid models, with the area under the receiver operating curve values of 0.920-0.926 versus 0.900-0.908, the area under the precision-recall curve values of 0.522-0.532 versus 0.485-0.513, and F2 scores of 0.595-0.601 versus 0.385-0.426. Logistic regression or logistic regression hybrid models had higher sensitivity than XGBoost or XGBoost hybrid models (0.837-0.857 vs 0.704-0.735) but a lower positive predictive value (0.122-0.141 vs 0.340-0.367) and specificity (0.793-0.821 vs 0.952-0.958). The hybrid versions of the logistic regression and XGBoost models had slightly higher areas under the precision-recall curve, specificity, and positive predictive values than the respective models that did not include any unsupervised features. XGBoost provided more accurate predictions of measles cases at the county level compared with logistic regression. The threshold of prediction in this model can be adjusted to align with each county's resources, priorities, and risk for measles. While clustering pattern data from unsupervised machine learning approaches improved some aspects of model performance in this imbalanced data set, the optimal approach for the integration of such approaches with supervised machine learning models requires further investigation.

Risk factors for measles outbreak in Al-Dali Governorate, Yemen

Background: In addition to the recent civil war in Yemen, the COVID-19 pandemic resulted in a collapse of the health system, a decline in vaccination coverage, and the spread of numerous outbreaks. In 2022, a measles outbreak impacted Al Dali governorate. This study aimed to describe the demographics of measles patients, measles risk factors, and disease outcomes in Al Dali Governorate, Yemen. Methods: All measles-infected children who sought medical attention at Al Tadhamon Hospital in Al Dali, Yemen, between February and December 2022 were included in this prospective and observational study. Results: During the study period, 154 parents gave their consent to enroll their children in this study; 88 (57.1%) were males, and 66 (42.9%) were females. The mean age of the children was 3.56±2.90 (0.3–12 years). More than half of the mothers (n=88, [57.1%]) were illiterate or had a basic educational level, while most of the fathers (n=126, [81.8%]) were well-educated. Nutritional status was normal in most children (n=146, [94.8%]), and all children were unvaccinated. Most children (n=152, [98.7]) came from areas having measles and most of them (n=130, [84.4]) were in contact with measles cases. Health facilities were close (<3 km) to many children (n=151 [98.1]), and house ventilation was good in 66.2% (n=102) of cases while crowdedness was found in 135 (87.7) cases. Family members were 7 or more in 90 (58.4) cases. Two children under the age of 5 years died because of the disease. Conclusion: Our study showed that the main risk factor for the recent measles outbreak in Al Dali governorate was lack of vaccination, as all involved children were unvaccinated. Routine immunization needs to be reinforced through health centers in different districts and community education about the dangers of the disease and the benefits of the vaccines should be enhanced to prevent outbreaks from recurring.

Spotting a potential threat: Measles among pediatric solid organ transplantation recipients.

Low-vaccination rates worldwide have led to the re-emergence of vaccine-preventable infections, including measles. Immunocompromised patients, including pediatric solid organ transplant (SOT) recipients, are at risk for measles because of suboptimal vaccination, reduced or waning vaccine immunity, lifelong immunosuppression, and global re-emergence of measles. To review published cases of measles in pediatric SOT recipients to heighten awareness of its clinical manifestations, summarize diagnostic and treatment strategies, and identify opportunities to optimize prevention. We conducted a literature review of published natural measles infections in SOT recipients ≤21 years of age, summarizing management and outcomes. We describe measles epidemiology, recommended diagnostics, treatment, and highlight prevention strategies. There are seven published reports of measles infection in 12 pediatric SOT recipients, the majority of whom were unvaccinated or incompletely vaccinated. Subjects had atypical or severe clinical presentations, including lack of rash and complications, most frequently with encephalitis and pneumonitis, resulting in 33% mortality. Updated recommendations on testing and vaccination are provided. Treatment options beyond supportive care and vitamin A are limited, with no approved antivirals. While measles is infrequently reported in pediatric SOT recipients, morbidity and mortality remain significant. A high index of suspicion is warranted in susceptible SOT recipients with clinically compatible illness or exposure. Providers must recognize this risk, educate families, and be aware of both classic and atypical presentations of measles to rapidly identify, isolate, and diagnose measles in pediatric SOT recipients. Continued efforts to optimize measles vaccination both pre- and post-SOT are warranted.

Dietary Vitamin A Intake and the Incidence of Diarrhea and Respiratory Infection among Sudanese Children

The relationship of vitamin A deficiency and child survival has been documented in a number of studies but not in others, yet the relationship of vitamin A with child morbidity remains controversial. We prospectively examined the relationship of dietary vitamin A intake and the incidences of diarrhea and respiratory infection among 28,753 Sudanese children between the ages of 6 mo and 6 y. Total dietary vitamin A intake was strongly and inversely associated with the risk of diarrhea (multivariate risk in top relative to bottom quintile = 0.58, 95% confidence interval = 0.47–0.72); we also observed a strong inverse association with the risk of having cough and fever (0.60, 0.45–0.81). On the other hand, we noted a significantly positive association of dietary vitamin A intake and incidence of cough alone (1.69, 1.52–1.88), a sign that may be associated with a healthy respiratory epithelium. Vitamin A intake was also negatively associated with the risk of measles. These prospective data emphasize the importance of adequate dietary vitamin A intake to protect the health of children in developing countries.

Prevention of Health Care–Associated Measles Transmission in a Pediatric Clinic

Abstract Objective Preventive measures in the setting of a suspected measles case in a hospital setting are important to stop the secondary spread. In this report, we evaluated the prevention attempts after two suspected cases of measles were reported in a pediatric clinic. Methods We evaluated prevention interventions including isolation, intravenous immunoglobulin, or measles–mumps–rubella (MMR) vaccine after two patients were diagnosed with maculopapular rash compatible with measles in the pediatric clinic. Results There were 50 patients (29 were outpatients, 21 were inpatients), 19 health care personnel (HCP), and 50 caregivers who were in contact with index cases. All of the HCP and 40 of the caregivers were immune to measles. Additional dose of MMR vaccine was recommended to five of the outpatients by phone. A total of 12 patients who were being followed up as inpatients (8 patients aged 6–12 months, 4 patients aged ≥ 12 months) were vaccinated with one dose of MMR vaccine. Only a 12-year-old male patient was admitted due to complaints suggesting measles after 14 days from discharge. It was learned that he had received a single dose of vaccine before so he was recommended an additional dose of MMR vaccine by the phone, but he did not go to the health institution on the day of the call. Conclusion Postexposure prophylaxis is effective to prevent measles transmission. Although young infants have the highest risk for transmission of measles in a health care–associated outbreak, adolescents and older children who are single vaccinated also have high risk for clinical measles.

A study on relationship between the incidence of measles and nosocomial exposure at measles epidemic season in Chongqing.

After measles vaccine supplementary immunization, the epidemiological characteristics of measles have changed in Chongqing, China. In addition, according to data from the National Measles Surveillance Information System, the proportion of measles cases with a history of hospital visit 7 to 21 days prior to onset of measles increased year by year to 32.1% in 2016. Further studies are necessary to eliminate the influence of nosocomial exposure on measles. We performed a case-control study in seven districts of Chongqing from June to August 2016 to identify risk factors for measles virus infection and susceptibility. Laboratory-confirmed measles who younger than 5 years old were matched with one control by age and residence. We interviewed case patients and controls regarding potential risk factors for measles virus infection and susceptibility. Unadjusted and adjusted matched odds ratios and 95% confidence intervals (CIs) were calculated using non-conditional logistic regression. After a cross-sectional analysis of the behavioral characteristics of visiting hospitals in the case and control groups, it was found that there was a difference between the two groups in the choice of hospitals visited for the first time (χ2 = 35.500, P = .000), and that nosocomial transmission risk tended to develop in outpatient services of respiratory medicine. After analysis using one-way ANOVA, the relationship between hospital visits prior to onset and the incidence risk of measles was that visiting hospitals five times within 1 to 3 weeks prior to onset affected the incidence (OR = 44.866, 95%CI = 5.938–338.981). The relationship between the number of types of hospitals visited prior to onset and the risk of nosocomial exposure to measles showed that visiting any community hospital, children’s hospital, or general hospital had no risk, but visiting two or more of these hospitals affected the incidence (OR = 6.928, 95%CI = 3.849–13.754). Based on further analysis, the relationship between the number of hospital visits after onset and the risk of nosocomial exposure to measles was that the chances of visiting hospitals increased after onset. Risks of nosocomial exposure to measles and infections are high in pediatric hospitals. Nosocomial exposure risk factors should be considered when controlling measles.

Vaccine Coverage in Children Younger Than 1 Year of Age during Periods of High Epidemiological Risk: Are We Preparing for New Outbreaks?

Background: According to WHO, infectious disease control can be achieved if the vaccine coverage (VC) exceeds 90%. In recent years there has been a declining trend in VC which could lead to the recurrence of infectious diseases. Objectives: The study analyzed the determinants of VC and of parental decisions regarding immunization in children aged 0–1 year monitored during two high-risk epidemiological periods (the measles epidemic and the COVID-19 pandemic period). Methods: A retrospective observational cohort study-data regarding vaccination of children younger than 1 year of age during the periods January 2019–June 2019 (measles epidemic) and January 2020–June 2020 (COVID-19 pandemic) were analyzed. 2.850 children from 2019 and 2.823 children from 2020 were enrolled. Family physicians interacted with 2840 parents or legal guardians in 2019 and with 2800 parents or legal guardians in 2020, during the infants’ consults providing medical information and answer to their questions and worries regarding their immunization. Data on immunization schedules on the determinants of parents’ decisions regarding vaccination were evaluated. Results: During 2019–2020, VC has followed a declining trend for each type of vaccine included in the Romanian National Immunization Program; the most affected were infants aged 9–12 months during both periods: in 9-month aged infants, the MMR vaccine VC was 67.49% in 2019 vs. 59.04% in 2020 (p < 0.004). In the 12 months aged infants, the MMR VC was 64.29% in 2019 vs. 55.88% in 2020 (p < 0.005). For the Hexavalent vaccine administered at the age of 11 months, the VC was 71.59% in 2019 vs. 62.08% in 2020 (p < 0.001). The determinants of parents’ decisions regarding vaccination included parental hesitance 2019—25% vs. 2020—35%, fear on side effects 2019—32% vs. 2020—45%, vaccination denial 2019—7% vs. 2020—10%. Conclusion: We found a declining trend in the VC in Romania during the epidemic and pandemic periods. The decrease in VC for MMR generated a major risk for new measles outbreaks Permanent awareness educational campaigns regarding infectious disease risk are needed, accompanied by the empowerment of primary care and the emergence of an immunization management program based on national regulatory legislation.

Understanding the transmission dynamics of a large-scale measles outbreak in Southern Vietnam

ObjectivesSouthern Vietnam experienced a large measles outbreak of over 26,000 cases during 2018-2020. We aimed to understand and quantify the measles spread in space-time dependence and the transmissibility during the outbreak. MethodsMeasles surveillance reported cases between January 2018 and June 2020, vaccination coverage, and population data at provinicial level were used. To illustrate the spatio-temporal pattern of disease spread, we employed the endemic-epidemic multivariate time series model decomposing measles risk additively into autoregressive, spatio-temporal, and endemic components. Likelihood-based estimation procedures were performed to determine the time-varying reproductive number Re of measles. ResultsOur analysis showed that the incidence of measles was associated with vaccination coverage heterogeneity and spatial interaction between provincial units. The risk of infections was dominated by between-province transmission (36.1% to 78.8%), followed by local endogenous transmission (4.1% to 61.5%). In contrast, the endemic behavior had a relatively small contribution (2.4% to 33.4%) across provinces. In the exponential phase of the epidemic, Re was above the threshold with a maximum value of 2.34 (95% CI: 2.20-2.46). ConclusionLocal vaccination coverage and human mobility are important factors contributing to the measles dynamics in Southern Vietnam, and the high risk of inter-provincial transmission is of most concern. Strengthening the disease surveillance is recommended, and further research is essential to understand the relative contribution of population immunity and control measures in measles epidemics.

Measles immunity in medical center staff after changes in national and local hospital vaccination policies

BackgroundMeasles vaccination was introduced in Taiwan in 1978, and the disease was declared eliminated in Taiwan in 2007. However, new cases have been reported unpredictably since then. Hospital medical staff are at particularly high risk for measles. We evaluated the immunity status of hospital medical staff after changes in national and local hospital vaccination policies.MethodsThis retrospective study was conducted in a tertiary care medical center from January 2008 to June 2018. Data were retrieved from all healthcare workers receiving employment medical examinations. Those with a full medical record including the geometrical mean titer (GMT) of anti-measles IgG were included. Age and sex differences in the GMT were analyzed by Student’s t-tests and Chi-squared tests. Univariate and multivariate logistic regression analysis were used to determine the odds of immunity.ResultsThe IgG positive rate increased with age group (p < 0.001). Seropositive rates for the birth before 1977 and after 1978 groups were 94.8% and 70.2% (p < 0.001). The odds ratio was also significantly different between both cohorts (1.000 vs. 0.423, p = 0.002). Staff in the examination department showed the lowest positive percentage of 70.3% (95% CI: 66.9–73.7%), whereas staff in preventive and long-term care services disclosed the highest positive percentage of 83.2% (95% CI: 76.1–90.2%). Subgroups 2015, 2017, and 2018 (p = 0.046, 0.046, 0.049), after the vaccination booster policy was launched, showed significant increases in seropositivity.ConclusionsImmunity efficacy is better in birth groups before 1977, which was highly related to natural infection before national policy launched. The policy of vaccination is an effective method, but medical staff attains inadequate protective antibody levels for maintenance of herd immunity. A pre-employment policy of screening a third booster vaccine of measles (or MMR) is recommended to lower the incidence of disease spreading and avoid outbreaks.

Evaluating Measles Incidence Rates Using Machine Learning and Time Series Methods in the Center of Iran, 1997-2020.

Background:Measles is a feverish condition labeled among the most infectious viral illnesses in the globe. Despite the presence of a secure, accessible, affordable and efficient vaccine, measles continues to be a worldwide concern.Methods:This epidemiologic study used machine learning and time series methods to assess factors that placed people at a higher risk of measles. The study contained the measles incidence in Markazi Province, the center of Iran, from Apr 1997 to Feb 2020. In addition to machine learning, zero-inflated negative binomial regression for time series was utilized to assess development of measles over time.Results:The incidence of measles was 14.5% over the recent 24 years and a constant trend of almost zero cases were observed from 2002 to 2020. The order of independent variable importance were recent years, age, vaccination, rhinorrhea, male sex, contact with measles patients, cough, conjunctivitis, ethnic, and fever. Only 7 new cases were forecasted for the next two years. Bagging and random forest were the most accurate classification methods.Conclusion:Even if the numbers of new cases were almost zero during recent years, age and contact were responsible for non-occurrence of measles. October and May are prone to have new cases for 2021 and 2022.

1344. Predicting Measles Outbreaks in the United States: Application of Different Modeling Approaches

Abstract Background Although measles is still rare in the United States (U.S.), there have been recent resurgent outbreaks in the U.S. To improve the accuracy of prediction given the rarity of measles events, we used machine learning (ML) algorithms to model measles case predictions at the U.S. county level. Methods The main outcome was occurrence of ≥1 measles case at the U.S. county level. Two ML prediction models were developed (HDBSCAN, a clustering algorithm, and XGBoost, a gradient boosting algorithm) and compared with traditional logistic regression. We included 28 predictors in the following categories: sociodemographics, population statistics, measles vaccination coverage, healthcare access, and exposure to measles via international air travel. The models were trained on 2014 case data and validated on 2018 case data. Models were compared using area under the receiver operating curve (AUC), sensitivity, specificity, positive predictive value (PPV), and F2 score (combined measure of sensitivity and PPV). Results There were 667 measles cases in 2014 and 375 in 2018 in the U.S. We identified U.S. counties for 635 (95.2%) cases in 2014 and 366 (97.6%) cases in 2018 through published sources, corresponding to 81/3143 (2.6%) counties in 2014 and 64/3143 (2.0%) counties in 2018 with ≥1 measles case. HDBSCAN had the highest sensitivity (0.92), but lowest AUC (0.68) and PPV (0.04) (Table). XGBoost had the highest F2 score (0.49), best balance of sensitivity (0.72) and specificity (0.94), and AUC = 0.92. Logistic regression had high AUC (0.91) and specificity (1.00) but the lowest sensitivity (0.16). Conclusion Machine learning approaches outperformed logistic regression by maximizing sensitivity to predict counties with measles cases, an important criterion to consider to prevent or prepare for future outbreaks. XGBoost or logistic regression could be considered to maximize specificity. Prioritizing sensitivity versus specificity may depend on county resources, priorities, and measles risk. Different modeling approaches could be considered to optimize surveillance efforts and develop effective interventions for timely response. Disclosures Stephanie Kujawski, PhD MPH, Merck &amp; Co., Inc. (Employee, Shareholder) Boshu Ru, Ph.D., Merck &amp; Co. Kenilworth, NJ (NYSE: MRK) (Employee, Shareholder) Amar K. Das, MD, PhD, Merck (Employee) richard baumgartner, PhD, Merck (Employee) Shuang Lu, MBA, MS, Merck (Employee) Matthew Pillsbury, PhD, Merck &amp; CO. (Employee, Shareholder) Joseph Lewnard, PhD, Merck (Consultant, Grant/Research Support) James H. Conway, MD, FAAP, GSK (Advisor or Review Panel member)Merck (Advisor or Review Panel member)Moderna (Advisor or Review Panel member)Pfizer (Advisor or Review Panel member)Sanofi Pasteur (Research Grant or Support) Manjiri D. Pawaskar, PhD, Merck &amp; Co., Inc. (Employee, Shareholder)