Insights into Clustering Patterns in Romania’s 2020–2024 Measles Cases

NSW immunisation performance: continuing progress but no room for complacency

A mathematical model to measure the impact of the measles control campaign on the potential for measles transmission in Australia

Background. Since 2014, California has experienced an increase in measles cases including a large outbreak associated with a theme park. We describe factors associated with measles transmission and clinical features of cases with ≥2 doses of MCV. Method. Measles cases reported to the California Department of Public Health (CDPH) from January 1, 2000–July 1, 2015 were reviewed. Measles transmitters were defined as patients who transmitted measles to one or more persons based on epidemiologic linkage, supported by appropriate timing and genotype data, when available. Ambiguous exposure situations were excluded. Multiple logistic regression was used to identify factors associated with measles transmission, including measles clinical features (cough, coryza, conjunctivitis, fever), vaccination status and age. Fisher's exact test was used in a sub-analysis of clinical features among those with verified immunization status. Result. Three hundred ninety-seven measles cases were reported to CDPH. In the multiple logistic regression model, coughing increased odds of transmission (OR: 3.3; 95% CI: 1.1–9.7), whereas age 2 doses of MCV. In a sub-analysis of those with documented vaccination status, cases with ≥2 MCV doses less frequently reported cough (p < 0.0001), coryza (p < 0.0001), conjunctivitis (p < 0.0001), fever (p < 0.01) and hospitalization (p = 0.03) versus unvaccinated cases or those with one dose. The median time since vaccination for cases with ≥2 MCV doses was 17 years (range: 6–39 years). Three patients with ≥2 MCV doses transmitted measles to close contacts; all reported cough while none of the patients with ≥2 MCV doses but without cough transmitted. Conclusion. Clinical and demographic features may be used to identify cases at high risk of transmitting measles and to prioritize investigation of their contacts. Prior vaccination appears to attenuate measles illness and reduce transmission. While some cases with ≥2 MCV doses are primary vaccine failures, the role of waning immunity among vaccinated people in measles outbreaks should be considered. Disclosures. J. Zipprich, Pfizer: Spouse works at Pfizer, Salary; J. D. Cherry, Global Pertussis Initiative: Member, Honoraria for participating and speaking at many GPI meetings since 2000. Sanofipasteur: Speaker's Bureau, Speaker honorarium

Estimating measles susceptibility and transmission patterns in Italy: an epidemiological assessment.

The varicella-zoster virus (VZV) vaccine strain may reactivate to cause herpes zoster. Limited data suggest that the risk of herpes zoster in vaccinated children could be lower than in children with naturally acquired varicella. We examine incidence trends, risk and epidemiologic and clinical features of herpes zoster disease among children and adolescents by vaccination status. Population-based active surveillance was conducted among <20 years old residents in Antelope Valley, California, from 2000 through 2006. Structured telephone interviews collected demographic, varicella vaccination and disease histories, and clinical information. From 2000 to 2006, the incidence of herpes zoster among children<10 years of age declined by 55%, from 42 cases reported in 2000 (74.8/100,000 persons; 95% confidence interval [95% CI]: 55.3-101.2) to 18 reported in 2006 (33.3/100,000; 95% CI: 20.9-52.8; P<0.001). During the same period, the incidence of herpes zoster among 10- to 19-year-olds increased by 63%, from 35 cases reported in 2000 (59.5/100,000 persons; 95% CI: 42.7-82.9) to 64 reported in 2006 (96.7/100,000; 95% CI: 75.7-123.6; P<0.02). Among children aged<10 years, those with a history of varicella vaccination had a 4 to 12 times lower risk for developing herpes zoster compared with children with history of varicella disease. Varicella vaccine substantially decreases the risk of herpes zoster among vaccinated children and its widespread use will likely reduce overall herpes zoster burden in the United States. The increase in herpes zoster incidence among 10- to 19-year-olds could not be confidently explained and needs to be confirmed from other data sources.

What will it take to end fatalities from measles?

Measles control in Australia – threats, opportunities and future needs

BackgroundIn Germany, measles vaccination coverage with two doses is not yet sufficient to prevent regional outbreaks. Among the 16 German federal states, vaccination coverage was lowest in Bavaria with 85% in 2008. From March to mid-April 2008, four neighbouring Bavarian counties reported 55 measles-cases mostly linked to an ongoing measles outbreak in an anthroposophic school in Austria. We investigated this outbreak to guide future public health action.MethodsWe applied the German national case-definition for measles and collected data using the national surveillance system and a questionnaire. Measles cases with disease onset a maximum of 18 days apart and spatial contact (e.g. same household, same school) were summed up in clusters. Two different interventions, which were implemented in schools and kindergartens in Bavaria, were compared by their impact on the size and duration of measles clusters. Susceptible persons were excluded from schools or kindergartens either with the first (intervention A) or second (intervention B) measles case occurring in the respective institution.ResultsAmong the 217 Bavarian measles cases identified from March-July 2008, 28 (13%) cases were attendees of the anthroposophic school in Austria. In total, vaccination status was known in 161 (74%) cases and 156 (97%) of them were not vaccinated. The main factor for non-vaccination was "fear of vaccine-related adverse events" (33%). Twenty-nine (18%) of 161 cases suffered complications. Exclusively genotype D5 was detected. Overall, 184 cases could be epidemiologically grouped into 59 clusters. Of those, 41 clusters could be linked to households and 13 to schools or kindergartens. The effect of intervention A and B was analysed in 10 school or kindergarten clusters. Depending on the respective intervention A or B, the median number of cases per cluster was 3 versus 13 (p = 0.05), and the median duration of a cluster was 3 versus 26 days (p = 0.13).ConclusionsIntroduction of measles virus into a pocket of susceptible persons (e.g. vaccination opponents or sceptics) may lead to large outbreaks in the general population, if the general population's vaccination coverage is below the WHO recommended level. Education on the safety of measles vaccine needs to be strengthened to increase measles vaccination coverage. Early intervention may limit spread in schools or kindergartens. Suspected measles has to be reported immediately to the local health authorities in order to allow intervention as early as possible.

Measles: A continuing saga

BackgroundOn 26 December 2004, a tsunami struck the coast of the state of Tamil Nadu, India, where one-dose measles coverage exceeded 95%. On 29 December, supplemental measles immunization activities targeted children 6 to 60 months of age in affected villages. On 30 December, Cuddalore, a tsunami-affected district in Tamil Nadu reported a cluster of measles cases. We investigated this cluster to estimate the magnitude of the problem and to propose recommendations for control.MethodsWe received notification of WHO-defined measles cases through stimulated passive surveillance. We collected information regarding date of onset, age, sex, vaccination status and residence. We collected samples for IgM antibodies and genotype studies. We modeled the accumulation of susceptible individuals over the time on the basis of vaccination coverage, vaccine efficacy and birth rate.ResultsWe identified 101 measles cases and detected IgM antibodies against measles virus in eight of 11 sera. Cases were reported from tsunami-affected (n = 71) and unaffected villages (n = 30) with attack rates of 1.3 and 1.7 per 1000, respectively. 42% of cases in tsunami-affected villages had an onset date within 14 days of the tsunami. The median ages of case-patients in tsunami-affected and un-affected areas were 54 months and 60 months respectively (p = 0.471). 36% of cases from tsunami-affected areas were above 60 months of age. Phylogenetic analyses indicated that the sequences of virus belonged to genotype D8 that circulated in Tamil Nadu.ConclusionMeasles virus circulated in Cuddalore district following the tsunami, although there was no association between the two events. Transmission despite high one-dose vaccination coverage pointed to the limitations of this vaccination strategy. A second opportunity for measles immunization may help reducing measles mortality and morbidity in such areas. Children from 6 month to 14 years of age must be targeted for supplemental immunization during complex emergencies.

Measles clinical presentation, hospitalization and vaccination status among children in a community-wide outbreak.

Background: Isolation of cases and quarantining of non-immune contacts are the mainstay of measles outbreak management in elimination settings. Serology testing of exposed contacts may not be feasible in large outbreaks; therefore, vaccination history is used as a proxy for determining immunity to measles and thus prevention of onward virus transmission. This study sought to investigate the risk of measles virus transmission from individuals with a history of one or two doses of measles-containing vaccine (MCV). Methods: Retrospective analysis of data from measles cases reported to Auckland Regional Public Health Service during the 2019 Auckland region measles outbreak. Vaccination history was verified using patient records and the New Zealand National Immunisation Register. Onward transmission was determined through case interviews and assessment of exposed contacts. Results: 1451 measles cases were assessed as eligible for vaccination at the time of measles outbreak. Of these, 1015 (70.0%) were unvaccinated, 220 (15.2%) had unknown vaccination status, 139 (9.6%) had received only one dose of MCV and 77 (5.3%) had received two doses of the vaccine. Compared to unvaccinated cases, the odds of onward transmission were lower among those with one dose only (OR 0.41, 95% CI: 0.20–0.75) or two doses of MCV (OR 0.44, 95% CI: 0.17–0.95). Median time since vaccination was longer among those with onward transmission compared to those without onward transmission for one and two doses of the vaccine, suggesting a potential effect of waning immunity among this cohort. Conclusion: These findings support the hypothesis that measles cases with a history of prior vaccination are less likely to transmit the virus to others compared to unvaccinated cases. Such information can be used to support decisions around quarantine requirements for vaccinated contacts in future measles outbreaks.

Germany scores own goal on measles

BackgroundAs China approaches the elimination of measles, outbreaks of measles continue to occur. Healthcare workers (HCWs) are known to be at high risk of infection and transmission of measles virus. A measles outbreak occurred in a hospital in Xinjiang Uighur Autonomous Region of the People’s Republic of China. We report an investigation of this outbreak and its implications for measles elimination and outbreak preparedness.MethodsWe conducted a retrospective search for measles cases using hospital records. Information on cases was collected by interview, and was used to determine epidemiological linkages. We surveyed HCWs to determine their demographic characteristics, disease history and vaccination status, and knowledge about measles.ResultsWe identified 19 cases, ages 18 to 45 years, in Hospital W between December 2015 and January 2016; 14 were laboratory-confirmed, and 5 were epidemiologically linked. The primary case was a 25-year-old neurology department nurse who developed a rash on 22 December 2015 that was reported on 11 January 2016. She continued working and living with her workmates in a dormitory during her measles transmission period. Among the 19 infected HCWs, 2 had received a dose of measles-containing vaccine (MCV) before the outbreak, and 16 had unknown vaccination status. Outbreak response immunization activities were started on 8 January in a non-selective manner by offering vaccine regardless of vaccination history; 605(68%) of 890 HCWs were vaccinated. The HCW survey had a 73% response rate (646/890); 41% of HCWs reported that they had received MCV before outbreak, and 56% exhibited good knowledge of measles symptoms, transmission, complications, and vaccination.ConclusionsLow MCV coverage, low measles knowledge among HCWs, delayed reporting of measles cases, and absence of proper case management were associated with this outbreak. Training and vaccinating HCWs against measles are essential activities to prevent measles virus transmission among HCWs.

There have been growing concerns of a potential re-establishment of measles transmission in the United States (US) in the years to come. This study aims to explore potential factors underlying the resurgence of measles in the US by objectively assessing the associations between annual incidence rates (AIR), case importation, vaccination status and disease outbreaks. Data on measles transmission between January 1st, 2001 and December 31st, 2019 were obtained from the national centres for disease control and prevention (CDC) surveillance databases and other published reports. Changes in incidence rates over time were assessed by binomial regression models. Of the 3874 cases of measles in the US over the study period, 3506 (90.5%, 95% CI: 89.5–91.4) occurred in US residents. The AIR per million population in US residents over this period was 0.60 (95% CI: 0.59–0.61), with an overall significant increase over time (p = 0.011). The median percentage of imported and vaccinated cases were 36% [17.9–46.6] and 15% [12.1–23.2] respectively. There was a significant decrease in the percentage of imported cases (p < 0.001) but not of vaccinated cases (p = 0.159) over time. There was a moderate and weak negative correlation between the AIR and the percentage of imported and vaccinated cases respectively (r = –0.59 and r = –0.27 respectively). On multiple linear regression there was a significant linear association between the AIR and the number of outbreaks (p = 0.003) but not with the percentage of imported cases (p = 0.436) and vaccinated cases (p = 0.692), R2 = 0.73. Strong negative and positive correlations were seen between the number of outbreaks and the percentage of imported cases (r = –0.61) and the of number states affected (r = 0.88) respectively. Despite the overall reduction in the percentage of imported cases of measles over the past two decades, pockets of internal transmission of the disease following importation via increasing number of outbreaks in unvaccinated subpopulations, reinforced by vaccine hesitancy, account for the sustained increase in measles incidence rates in the US. Controlling indigenous transmission through efficient vaccination coverage in at-risk subpopulations and among international US travellers, improved disease surveillance and rapid outbreak containment are essential in curbing the measles resurgence.