Measles vaccination - An underestimated prevention measure: Analyzing a fatal case in Hildesheim, Germany.

Measles and rubella are targeted for elimination in the WHO region Europe. To reach the elimination goal, vaccination coverage of 95% must be achieved and sustained, the genotype information has to be provided for 80% of all outbreaks and transmission chains of a certain variant must not be detected for >12 months. The latter information is collected at Germany's National Reference Center Measles, Mumps, Rubella (NRC MMR). We describe here an outbreak of measles occurring in Hildesheim. The outbreak comprised 43 cases and lasted 14 weeks. Surprisingly, a high number of vaccination failures was observed since 11 cases had received two doses of the MMR vaccine and 4 additional cases were vaccinated once. A 33-year-old woman passed away during the outbreak. She was the mother of 5 children between 4 and 16 years of age. Two schoolchildren contracted measles and passed it on to the rest of the family. Due to delivery bottlenecks, the vaccination of the mother was delayed. She developed measles-like symptoms 3 days after vaccination and was found dead on the morning of day 8 after vaccination. A post-mortem examination was done to identify the cause of death. Moreover, molecular characterization of the virus was performed to analyze whether she was infected by the wildtype virus circulating at that time in Hildesheim or whether the vaccine may have been a concomitant and aggravating feature of her death. The result showed that the samples taken from her at the time of death and during necropsy contained the wildtype measles virus variant corresponding to MVs/Gir Somnath.IND/42.16 (WHO Seq-ID D8-4683) that fueled the Hildesheim outbreak and circulated in Germany from March 2018 to March 2020. The vaccine virus was not detected. Moreover, two aspects uncovered by the post-mortem examination were remarkable; the woman died from giant cell pneumonia, which is a complication seen in immune-suppressed individuals and she was actively using cannabis. THC is known to influence the immune system, but literature reports describing the effects are limited.

Differential diagnosis on measles and rubella discarded cases highlights a sharp increase in parvovirus B19 infections in Milan, Northern Italy, in the first months of 2024.

In line with European trends, since 2023 Lombardy (Northern Italy) is experiencing a resurgence of measles and an increased number of reported cases of fever and rash. Measles discarded cases observed in our region within the context of measles and rubella surveillance from the first few months of 2024 (N = 30) were investigated for parvovirus B19 (B19V) and other rash-associated viruses. Thirteen cases tested positive for B19V DNA, representing a significant increase from previous years (on average 3 cases per year, p < 0.001) and ~40% of all B19V DNA-positive patients we detected since 2017. In 2024, B19V DNA-positive subjects spanned all ages, and the virus was predominant among adolescents and adults (84.6%). Two B19V infected patients were hospitalised, and likely cross-reacting anti-measles virus IgM were found in both. Our data align with the recent reports from the ECDC and various European countries, which are experiencing a surge in B19V infections, and underline the importance of comprehensive measles and rubella surveillance systems that can adapt to changing epidemiological trends.

Progress Toward Rubella and Congenital Rubella Syndrome Elimination - Worldwide, 2012-2022.

Rubella virus is a leading cause of vaccine-preventable birth defects. Infection during pregnancy can result in miscarriage, fetal death, stillbirth, or a constellation of birth defects, including cataracts, deafness, heart defects, and developmental delay, known as congenital rubella syndrome (CRS). A single dose of rubella-containing vaccine can provide lifelong protection against rubella. The Global Vaccine Action Plan 2011-2020 included a target to achieve elimination of rubella in at least five of the six World Health Organization (WHO) regions by 2020, and rubella elimination is a critical goal of the Immunization Agenda 2030. This report updates a previous report and describes progress toward rubella and CRS elimination during 2012-2022. During 2012-2022, among 194 WHO countries, the number that included rubella-containing vaccine (RCV) in their immunization schedules increased from 132 (68%) to 175 (90%) and the percentage of the world's infants vaccinated against rubella increased from 40% to 68%. Reported rubella cases declined 81%, from 93,816 in 2012 to 17,407 in 2022. Verification of rubella elimination was achieved in 98 (51%) of 194 countries by 2022, an increase from 84 (43%) countries in 2019. Despite significant progress in the introduction of RCV into routine immunization programs worldwide, approximately 25 million infants annually still do not have access to RCV. Nevertheless, even in complex settings, the increasing number of countries that have achieved and sustained rubella elimination demonstrates progress toward global rubella elimination.

Rubella virus seropositivity after infection or vaccination as a risk factor for multiple sclerosis.

BACKGROUND: Multiple sclerosis (MS) is a demyelinating disease affecting millions of people worldwide. Hereditary susceptibility and environmental factors contribute to disease risk. Infection with Epstein-Barr virus (EBV) and human herpesvirus 6A (HHV-6A) have previously been associated with MS risk. Other neurotropic viruses, such as rubella virus (RV), are possible candidates in MS aetiopathogenesis, but previous results are limited and conflicting. METHODS: In this nested case-control study of biobank samples in a Swedish cohort, we analysed the serological response towards RV before the clinical onset of MS with a bead-based multiplex assay in subjects vaccinated and unvaccinated towards RV. The association between RV seropositivity and MS risk was analysed with conditional logistic regression. RESULTS: Seropositivity towards RV was associated with an increased risk of MS for unvaccinated subjects, even when adjusting for plausible confounders including EBV, HHV-6A, cytomegalovirus and vitamin D (adjusted odds ratio [AOR] = 4.0, 95% confidence interval [CI] 1.8-8.8). Cases also had stronger antibody reactivity towards rubella than controls, which was not seen for other neurotropic viruses such as herpes simplex or varicella zoster. Furthermore, we observed an association between RV seropositivity and MS in vaccinated subjects. However, this association was not significant when adjusting for the aforementioned confounders (AOR = 1.7, 95% CI 1.0-2.9). CONCLUSIONS: To our knowledge, these are the first reported associations between early RV seropositivity and later MS development. This suggests a broadening of the virus hypothesis in MS aetiology, where molecular mimicry between rubella epitopes and human central nervous system molecules could be an attractive possible mechanism.

Seroconversion and seroprevalence of TORCH infections in a pregnant women cohort study, Mombasa, Kenya, 2017-2019.

Women infected during pregnancy with TORCH (Toxoplasmosis, Other, Rubella, Cytomegalovirus, and Herpes simplex viruses) pathogens have a higher risk of adverse birth outcomes including stillbirth / miscarriage because of mother-to-child transmission. To investigate these risks in pregnant women in Kenya, we analyzed serum specimens from a pregnancy cohort study at three healthcare facilities. A sample of 481 participants was selected for TORCH pathogen antibody testing to determine seroprevalence. A random selection of 285 from the 481 participants was selected to measure seroconversion. These sera were tested using an IgG enzyme-linked immunosorbent assay against 10 TORCH pathogens. We found that the seroprevalence of all but three of the 10 TORCH pathogens at enrollment was >30%, except for Bordetella pertussis (3.8%), Treponema pallidum (11.4%), and varicella zoster virus (0.5%). Conversely, very few participants seroconverted during their pregnancy and were herpes simplex virus type 2 (n = 24, 11.2%), parvovirus B19 (n = 14, 6.2%), and rubella (n = 12, 5.1%). For birth outcomes, 88% of the participant had live births and 12% had stillbirths or miscarriage. Cytomegalovirus positivity at enrolment had a statistically significant positive association with a live birth outcome (p = 0.0394). Of the 10 TORCH pathogens tested, none had an association with adverse pregnancy outcome.

Assessing seropositivity of MMR antibodies in individuals aged 2-22: evaluating routine vaccination effectiveness after the 2003 mass campaign-a study from Iran's National Measles Laboratory.

BACKGROUND AND PURPOSE: The seroprevalence of antibodies against measles, mumps, and rubella (MMR) was evaluated 17 years following a mass vaccination campaign in individuals aged 2 to 22 years who had received routine immunization but were not eligible for an extended immunization program. METHODS: Samples were acquired from Iran's National Measles Laboratory (NML), with individuals showing positive IgM results excluded. Out of the samples collected in 2020, a random selection of 290 serum samples was chosen, representing individuals between the ages of 2 and 22 years from diverse regions in the country. These samples were subjected to analysis using an enzyme-linked immunosorbent assay (ELISA) to quantify specific IgG antibodies against MMR. RESULTS: The seroprevalence rates of antibodies for measles, mumps, and rubella were determined to be 76.2%, 89.3%, and 76.9%, respectively. Younger age groups exhibited higher seropositivity rates for measles and mumps, whereas the 7- to 11-year-old group demonstrated the highest seropositivity rate for rubella. A reduction in antibody status was observed from younger to older age groups, particularly those aged 17-22. CONCLUSION: The study unveiled suboptimal antibody levels for measles and rubella, highlighting the necessity for further investigation and potential adjustments to future vaccination strategies. Moreover, the decline in antibody status post-vaccination can accumulate in seronegative individuals over time, elevating the risk of outbreaks.

Rubella epidemiology in Lesotho after vaccine introduction: a five-year review, 2018-2022.

BACKGROUND: The rubella virus is a major contributor to birth defects globally and is preventable by vaccination. In 2020, the world was supposed to be free of both rubella and Congenital Rubella Syndrome (CRS) however this goal has yet to be realized with only 93 out of 194 WHO member states confirmed rubella-free in 2020. METHODS: A retrospective measles and rubella case-based surveillance data record review was conducted from 2018 to 2022 to document rubella epidemiology after the introduction of rubella vaccination in Lesotho and progress toward elimination. All samples submitted for surveillance purposes and tested for rubella were considered but only filtered according to inclusion and exclusion criteria. Descriptive statistics were used to analyse the data. RESULTS: Of the 1041 samples that were tested for rubella between 2018 and 2022, 10 (1%) were confirmed measles positive and were excluded from further analysis. The median age of the respondents was 6.0 (IQR 4.0-8.0.) years. About 643 (62.4%) of respondents were in the age category of 5 - <13 years. Rubella prevalence was 1% (95% CI; 0.5 -1.8%). The non-measles, non-rubella rash illness rate of 2 per 100 000 population was obtained at the national level each year of the study period but by only 2 of the country's 10 districts in 2021. CONCLUSIONS: The study showed low rubella prevalence. Rubella infection was predominant in those aged 5 - < 13 years. Failure to meet surveillance targets at certain time points during the study period may have led to an underestimation of rubella cases. There is a need to improve the quality of measles and rubella surveillance in Lesotho. Supplementary immunization activities would also be useful in closing immunity gaps, limiting outbreaks, and advancing rubella and CRS elimination in Lesotho.

[Analysis of serum IgM antibody and viral nucleic acid test results in measles and rubella cases in China from 2014 to 2023].

Objective: To analyze the results of serum IgM antibody and viral nucleic acid testing in measles and rubella cases in China from 2014 to 2023. Methods: Surveillance data on measles and rubella during 2014-2023 were obtained from the Chinese Disease Prevention and Control Information System, and cases that underwent measles/rubella IgM antibody testing and viral nucleic acid testing were included in the study. Information on the number of cases, vaccination status, and laboratory test results was collected, and laboratory test results were compared among cases with different times of rash or onset and different doses of vaccination. Results: From 2014 to 2023, the total number of measles and rubella surveillance cases was 581 746, and the number of measles and rubella cases that underwent both IgM antibody and viral nucleic acid testing was 39 124 and 21 766, respectively, with a double-positive rate of IgM antibody and viral nucleic acid testing of 63.73% (for measles) and 41.68% (for rubella). The single-positive rate for IgM antibody was 21.12% (for measles) and 27.15% (for rubella). The single-positive rate for viral nucleic acid tests was 13.84% (for measles) and 28.19% (for rubella). According to different days of rash or onset (0-3, 4-5, 6-10 and >10), samples of 24 629 (62.95%) measles cases and 15 785 (72.52%) rubella cases were from within 3 days of rash or onset, and the single positive rate of viral nucleic acid detection was 16.90% (for measles) and 32.07% (for rubella). The single positive rate of IgM antibody increased gradually with the time of onset (measles: χ2trend=314.098, P<0.001, rubella: χ2trend=763.846, P<0.001), and reached 31.66% (for measles) and 53.12% (for rubella) after 10 days of rash or onset. Depending on the number of vaccination doses (1, 2,≥3), the single positive rate of viral nucleic acid detection ranged from 12.93% to 20.29% (for measles) and from 25.30% to 27.88% (for rubella). The single positive rate of IgM antibody detection ranged from 36.89% to 47.47% (for measles) and from 22.81 to 41.15% (for rubella). Conclusions: Combined testing of serum IgM antibody and viral nucleic acids could facilitate laboratory confirmation of measles and rubella cases and was also important for measles and rubella elimination efforts.

Anti-rubella seroprevalence assessment in an adult sample population in Italy.

Introduction: Despite global immunization efforts, rubella remains a public health concern, particularly in high- and middle-income countries. This study focused on rubella seroprevalence in the province of Florence, Italy, aiming to identify susceptibility clusters, especially among women in their childbearing age. Methods: A cross-sectional study was conducted between April 2018 and December 2019, enrolling 430 adult subjects (age over 18 years). Serum samples were collected, and anti-rubella antibodies were quantified using the ELISA test. Data were analyzed descriptively and compared by sex, nationality, and age groups using statistical tests. Results: The overall rubella seroprevalence was high (92.3%), with no significant differences between genders or nationalities. Among childbearing-age females (18-49 years), the highest seroprevalence was observed in the 30-39 age group (94.1%). However, susceptibility clusters exceeding the 5% threshold set by WHO were identified, especially in females aged 40-49 years (7.0%). Conclusions: Despite high overall seroprevalence, the study identified pockets of susceptibility, even in childbearing age women. Continuous monitoring, targeted immunization strategies, and public health interventions are recommended to maintain rubella elimination, emphasizing the importance of sustained vaccination efforts to protect vulnerable populations.

Rubella in Poland in 2021. / Rózyczka w Polsce w 2021 roku.

INTRODUCTION: Rubella is a viral infectious disease, and humans are the only reservoir of the virus. In 2020, all WHO member countries conducted epidemiological surveillance for rubella, and almost all (99%) had access to rubella testing at laboratories operating under the WHO Global Measles and Rubella Laboratory Network. OBJECTIVES: The aim of this study was to evaluate epidemiological indicators of rubella 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, 50 cases of rubella were registered, 48 fewer than in 2020 (98 cases). There was also a decrease in incidence to 0.13 per 100,000, compared to 0.26 per 100,000 in 2020. The highest incidence, regardless of gender and residential environment, was recorded in the 0-4 age group (1.23 per 100 thousand). No cases of congenital rubella syndrome were reported in 2021. CONCLUSIONS: In 2021, there was a decrease in the number of rubella cases in Poland, which could be a result of the COVID-19 pandemic and the introduced restrictions. In addition, rubella was registered 99% on the basis of clinical diagnoses, without the required laboratory confirmation, which means that other rash diseases could be registered as rubella.

Quantification of Waning Immunity After Measles Vaccination-Evidence From a Seroprevalence Study.

We aimed to quantify rates of waning immunity after measles vaccination from seroprevalence data collected in a study of a population with high vaccination coverage and a fixed vaccination schedule. Data were collected during a national survey (the Immunological Survey) carried out in the Slovak Republic in 2018. The average rate of waning immunity against measles after the first dose of measles, mumps, and rubella (MMR) vaccine (ages 1.5-10 years) was 9.7% per year from the geometric mean titer value of 2,634 mUI/mL. The average waning rate after the second dose of MMR vaccine (ages 10-33 years) was significantly lower: 4.8% per year from the lower geometric mean titer of 1,331 mUI/mL. This decline in antibody levels suggests that vaccine-induced protection may be compromised and results in an increase in the proportion of seronegative/borderline individuals. These outcomes may provide a valuable source for critical assessment of direct and indirect effects of MMR vaccination.

Rubella.

Rubella is an acute illness caused by rubella virus and characterised by fever and rash. Although rubella is a clinically mild illness, primary rubella virus infection in early pregnancy can result in congenital rubella syndrome, which has serious medical and public health consequences. WHO estimates that approximately 100 000 congenital rubella syndrome cases occur per year. Rubella virus is transmitted through respiratory droplets and direct contact. 25-50% of people infected with rubella virus are asymptomatic. Clinical disease often results in mild, self-limited illness characterised by fever, a generalised erythematous maculopapular rash, and lymphadenopathy. Complications include arthralgia, arthritis, thrombocytopenic purpura, and encephalitis. Common presenting signs and symptoms of congenital rubella syndrome include cataracts, sensorineural hearing impairment, congenital heart disease, jaundice, purpura, hepatosplenomegaly, and microcephaly. Rubella and congenital rubella syndrome can be prevented by rubella-containing vaccines, which are commonly administered in combination with measles vaccine. Although global rubella vaccine coverage reached only 70% in 2020 global rubella eradiation remains an ambitious but achievable goal.

Measles in vulnerable populations: An outbreak in Roma settlements of Loire-Atlantique, France, 2019.

In May 2019, a measles outbreak occurred in the French subregion of Loire-Atlantique, particularly affecting Roma settlements. Various obstacles hindered the implementation of postexposure measures among Roma population, resulting in the spread of the cases to other settlements. Suspected cases of measles were immediately investigated and concerned settlements were visited for measles-mumps-rubella (MMR) vaccination. From July 1 to September 3, 2019, a first and then a second Health Reserve team helped for vaccination on the affected and then also the measles-free settlements. Vaccination uptake was monitored with the use of the department's vaccination center immunization registry. Genotyping of selected samples was performed for comparison with viruses circulating at the same time in France and Romania. As of September 16 2019, 109 cases of measles were confirmed among Roma population, including 99 (91%) children under 15 years. Of the 85 people eligible for vaccination, 60 (71%) had not been vaccinated and 23 (27%) had an unknown vaccination status. Sequence comparison revealed that 28/29 sequenced D8 strains were 100% identical to the strain responsible for a large number of cases throughout France in 2019, and to two sequences reported in Romania among sporadic cases. The vaccination campaign resulted in 1136 people on 35 settlements receiving at least one dose of MMR vaccine and in the increase of one-dose MMR vaccine coverage at 24 months from 43% (23/53) to 91% (48/53). With measles transmission continuing in Europe, efforts must be made to meet immunization coverage targets, particularly in hard-to-reach communities where outbreaks may be difficult to control.

Seroepidemiology study of rubella virus antibodies among neonates and pregnant women at hospitals in Henan province, China.

Rubella virus infection can cause vertical transmission to the fetus during pregnancy. In China's Henan province, rubella surveillance needs to be well-established. In this research, a total of 1933 neonates and 2502 pregnant women were enrolled, and their sera for IgG and IgM antibodies against rubella were tested by chemiluminescence assay. Of 1933 neonates' sera tested, the seropositive of rubella IgG was 68.7%. The seroprevalence of rubella IgM in neonates was 0.4%. 30.9% of neonates had negative results for IgG and IgM antibodies. Two thousand five hundred and two pregnant women participated in the serosurvey, and 79.3% were rubella IgG positive. Rubella IgG seropositivity in pregnant women differed by age and number of births. 0.8% of the pregnant women had positive results for IgM against the rubella virus. The seronegative of rubella IgG and IgM antibodies in pregnant women was 19.8%. Due to the negative rubella-specific IgG antibody, many neonates remain at risk of rubella virus infection. Rubella virus continues to spread since some neonates and pregnant women with rubella-specific IgM antibody positive have been detected. Rubella vaccination may be introduced for childbearing-age women to increase immunity levels against rubella with periodic sero-surveillance.

Contribution of parvovirus B19 in suspected cases of measles/rubella in Osaka, Japan, between 2011 and 2021.

Erythema infectiosum, caused by human parvovirus B19 (B19V), is difficult to diagnose by its clinical symptoms and is often misdiagnosed as measles or rubella. Timely confirmation of measles/rubella or other viral etiologies via laboratory tests can provide an accurate picture of the infection status, which can appropriate response. The purpose of this study was to determine the contribution of B19V as an etiological agent for fever-rash in suspected cases of measles and rubella in Osaka Prefecture between 2011 and 2021. Of 1356 suspected cases, 167 were confirmed with measles and 166 with rubella using nucleic acid testing (NAT). Of the remaining 1023 cases, 970 from which blood specimens could be obtained were screened by real-time polymerase chain reaction for B19V, from which 136 (14%) tested positive. Of the positives cases, 21% were young children (9 years and younger), while 64% were adults (20 years and older). Phylogenetic tree analysis showed that 93 samples belonged to genotype 1a. The importance of B19V in the etiology of fever-rash illness was revealed in this study. The importance of laboratory diagnosis by NAT in maintaining the status of measles elimination and to eliminate rubella was reaffirmed.

Differential diagnosis of fever and rash cases negative for measles and rubella to complement surveillance activities.

In the quest to eliminate measles virus (MV) and rubella virus (Ruv), every suspected case must be properly identified and diagnosed. Since 2017, in Milan (Italy), a total of 978 measles and rubella suspected cases (fever and rash) were investigated and 310 were not laboratory confirmed (discarded cases). To improve surveillance activities, we investigated the presence in discarded cases of 8 other viral pathogens commonly associated with rash: human herpesvirus 6 (HHV-6) and 7 (HHV-7), parvovirus B19 (B19V), enterovirus (EV), Epstein-Barr virus (EBV), human adenovirus (HAdV), cytomegalovirus (HCMV), and SARS-CoV-2. Differential diagnosis was carried out on 289 discarded cases by multiplex real-time PCR assays. At least one pathogen was detected in 188 cases (65.1%) with HHV-7 being the most frequently detected virus. No difference in the number of detected infections overtime was observed and infections were identified in all age groups. As expected, most HHV-6, EV, HAdV, and HCMV-positive cases were found in children aged 0-4 years and HHV-7 was most frequent in the 15-39 age group. In light of the World Health Organization measles elimination goal, the introduction of laboratory methods for differential diagnosis is required for the final classification of clinically compatible cases. The used screening panel allowed us to increase the percentage of virus-positive cases to 87.5%, allowing us to clarify viral involvement and epidemiology, improve diagnosis, and strengthen surveillance activities. As all investigated pathogens were detected, this diagnostic panel was a suitable tool to complement MV and RuV surveillance activities.

Progress Toward Rubella Elimination - World Health Organization South-East Asia Region, 2013-2021.

During 2013, the 11 countries of the World Health Organization (WHO) South-East Asia Region* (SEAR) adopted the goals of measles elimination and rubella and congenital rubella syndrome (CRS) control† by 2020. During 2019, SEAR countries declared a broader goal for eliminating both measles and rubella§ by 2023 (1). Before 2013, only five SEAR countries had introduced rubella-containing vaccine (RCV). This report updates a previous report and describes progress toward rubella elimination in SEAR during 2013-2021 (2). During 2013-2021, six SEAR countries introduced RCV; all countries in the Region now use RCV in routine immunization. Routine immunization coverage with the first dose of a rubella-containing vaccine (RCV1) increased >600%, from 12% during 2013 to 86% during 2021, and an estimated 515 million persons were vaccinated via RCV supplementary immunization activities (SIAs)¶ during 2013-2021. During this time, annual reported rubella incidence declined by 80%, from 5.5 to 1.1 cases per million population. Maldives and Sri Lanka are verified as having achieved rubella elimination; Bhutan, North Korea, and Timor-Leste have halted endemic transmission of rubella virus for >36 months. SEAR has made substantial progress toward rubella elimination; however, intensified measures are needed to achieve elimination.

Progress Toward Measles and Rubella Elimination - Indonesia, 2013-2022.

In 2019, Indonesia and the other countries in the World Health Organization South-East Asia Region adopted the goal of measles and rubella elimination by 2023. This report describes Indonesia's progress toward measles and rubella elimination during 2013-2022. During this period, coverage with a first dose of measles-containing vaccine (MCV) decreased from 87% to 84%, and coverage with a second MCV dose decreased from 76% to 67%. After rubella vaccine was introduced in 2017, coverage with the first dose of rubella-containing vaccine increased approximately fivefold, from 15% in 2017 to 84% in 2022. During 2013-2021, annual reported measles incidence decreased by 95%, from 33.2 to 1.4 cases per million population; reported rubella incidence decreased 89%, from 9.3 to 1.0 cases per million population. However, a large surge in measles and rubella cases occurred in 2022, with a reported measles incidence of 29 cases per million and a reported rubella incidence of 3 per million, primarily related to disruption in immunization services caused by the COVID-19 pandemic. In 2022, approximately 26 million children (an estimated 73% of the target population) received a combined measles- and rubella-containing vaccine during supplementary immunization activities completed in 32 provinces. Progress toward measles and rubella elimination in Indonesia has been made; however, continued and urgent efforts are needed to restore routine immunization services that were adversely affected by the COVID-19 pandemic and close immunity gaps to accelerate progress toward measles and rubella elimination.

Estimates of the basic reproduction number for rubella using seroprevalence data and indicator-based approaches.

The basic reproduction number (R0) of an infection determines the impact of its control. For many endemic infections, R0 is often estimated from appropriate country-specific seroprevalence data. Studies sometimes pool estimates from the same region for settings lacking seroprevalence data, but the reliability of this approach is unclear. Plausibly, indicator-based approaches could predict R0 for such settings. We calculated R0 for rubella for 98 settings and correlated its value against 66 demographic, economic, education, housing and health-related indicators. We also trained a random forest regression algorithm using these indicators as the input and R0 as the output. We used the mean-square error to compare the performances of the random forest, simple linear regression and a regional averaging method in predicting R0 using 4-fold cross validation. R0 was <5, 5-10 and >10 for 81, 14 and 3 settings respectively, with no apparent regional differences and in the limited available data, it was usually lower for rural than urban areas. R0 was most correlated with educational attainment, and household indicators for the Pearson and Spearman correlation coefficients respectively and with poverty-related indicators followed by the crude death rate considering the Maximum Information Coefficient, although the correlation for each was relatively weak (Pearson correlation coefficient: 0.4, 95%CI: (0.24,0.48) for educational attainment). A random forest did not perform better in predicting R0 than simple linear regression, depending on the subsets of training indicators and studies, and neither out-performed a regional averaging approach. R0 for rubella is typically low and using indicators to estimate its value is not straightforward. A regional averaging approach may provide as reliable an estimate of R0 for settings lacking seroprevalence data as one based on indicators. The findings may be relevant for other infections and studies estimating the disease burden and the impact of interventions for settings lacking seroprevalence data.

Etiological analysis of discarded measles in the context of a measles outbreak among a highly immunized population.

BACKGROUND: Measles can lead to serious complications and remains an important cause of morbidity and mortality worldwide. In this study we aimed to assess the etiological diagnosis of discarded measles cases in the context of an outbreak among a highly immunized population. METHODS: We conducted a retrospective observational study of discarded measles cases from an outbreak that occurred from October 2006 to July 2007 in Catalonia. A confirmed case was defined as having a positive measles serum IgM result and/or a positive result by RT-PCR in urine and/or nasopharyngeal swab; or an epidemiological link to a confirmed case. Serum specimens were tested by a commercially available indirect-format and by an in-house capture-format measles IgM enzyme immunoassays. RESULTS: Testing of 89 samples discarded for measles determined the etiologies for 10 (11.2%), including one rubella, three human herpes virus 6, and six measles infections. Of 381 confirmed cases in the outbreak, 10% had received at least one dose of the measles-mumps-rubella vaccine versus 54% of the discarded for measles (OR: 0.09; 95% CI: 0.06, 0.14; p < 0.001). CONCLUSIONS: Highly sensitive surveillance systems are critical to identifying cases, responding to outbreaks and verifying progress towards measles elimination. Molecular tools for measles detection and differential diagnosis, and collection of appropriate specimens for molecular and serological testing are essential to correctly diagnose suspected measles infection.