Measles is a highly infectious respiratory virus with the potential to cause severe illness resulting in hospitalization or death. On January 29, 2025, the Texas Department of State Health Services Public Health Region 1 was notified by the South Plains Public Health District of a case of measles in an unvaccinated school-aged child. During January 20-March 18, 2025, a total of 325 confirmed measles cases were reported; 60 (18.5%) patients were hospitalized. Available medical records for 54 hospitalized patients were reviewed; 49 (90.7%) were aged <18 years, and 48 (88.9%) had no underlying medical conditions. All 54 were unvaccinated or had unknown vaccination status. Hospitalized patients were admitted for a median of 2 days (range = 0-20 days) and many experienced complications, including pneumonia (39; 72.2%), dehydration (25; 46.3%), hepatitis (one; 1.9%), and febrile seizures (one; 1.9%). Thirty-eight (70.4%) hospitalized patients required supplemental oxygen, four (7.4%) were admitted to an intensive care unit, two (3.7%) required intubation and mechanical ventilation, and one (1.9%) died. Although most persons with confirmed measles were not hospitalized, approximately one in five required hospitalization, consistent with previously reported rates. Vaccination remains a critical tool for the prevention of measles infection and severe disease.

BACKGROUND:On 7 March 2024, the Chicago Department of Public Health was notified of a positive measles test in a resident of a shelter housing >2100 persons. We estimated the effectiveness of measles-mumps-rubella vaccine (MMR) administered during the outbreak to guide its use as an acute intervention. METHODS:We used Pearson χ2 tests to compare unadjusted attack rates (ARs) by age group, number of days exposed, and sex. We estimated adjusted hazard ratios (aHRs) using time-dependent Cox proportional hazards regression models to assess the association between time-varying MMR dose status and the outcome of laboratory-confirmed measles; the final model was adjusted for time-varying exposure to measles virus and age group. We estimated risk-adjusted vaccine effectiveness (VE) as VE = (1 - aHR) × 100. RESULTS:Measles was diagnosed in 52 of 2243 (2.3%) residents who resided in the shelter for ≥1 day during 22 February-4 April 2024. ARs were highest among children aged <6 months (57.1%) and 6-11 months (55.6%) and among residents who were exposed for 8-13 days (10.1%). ARs did not differ by sex. Estimated 1-dose VE was 70% (95% confidence interval [CI], 28%-88%) and estimated ≥2-dose VE was 72% (95% CI, 21%-90%). CONCLUSIONS:This study provided a unique opportunity to evaluate MMR VE in a contemporary outbreak setting with a high force of infection and could guide future responses in similar congregate settings. MMR was effective at preventing measles among shelter residents. Public health efforts that prioritize vaccinating persons without ≥2 MMR doses remain critical for limiting transmission.

BACKGROUND:The most recent assessment of antibodies against measles, mumps, rubella, and varicella-zoster viruses (MeV, MuV, RuV, VZV) in the United States was conducted in 2009-2010. Regular assessments are essential to measure the impact of immunization programs, identify immunity gaps, and inform vaccination strategies. We report updated estimates of national seroprevalence. METHODS:We used a CDC-developed immunoglobulin G multiplex bead assay to quantitatively detect antibodies against MeV, MuV, RuV, and VZV among participants aged 6-59 years in the 2017-March 2020 National Health and Nutrition Examination Survey. We estimated seroprevalence overall and by sociodemographic characteristics and assessed independent predictors of seropositivity using logistic regression models with weighted procedures for complex survey design. RESULTS:Overall seroprevalence was 95.2% (95% CI, 94.0%-96.3%) against MeV, 87.8% (95% CI, 86.5%-89.2%) against MuV, 95.6% (95% CI, 94.5%-96.5%) against RuV, and 97.2% (95% CI, 96.4%-98.0%) against VZV, and remained high across advancing age groups. Younger age and non-Hispanic Black race and ethnicity were independent predictors for MeV, MuV, and RuV seropositivity; sex, birthplace, and health insurance status were independent predictors for seropositivity for at least one of the viruses. CONCLUSIONS:Nationally, seroprevalence for MeV, MuV, RuV, and VZV antibodies remains high among persons aged 6-59 years and our findings indicate robust antibody responses are maintained decades after vaccination or natural infection. Maintaining high population immunity through vaccination is critical to prevent cases and outbreaks of all four vaccine-preventable diseases.

During 2025, the United States recorded the highest number of measles cases since measles elimination was declared in 2000. On March 21, 2025, Lubbock Public Health (LPH) in Texas received a report of a child care attendee aged 3 years, with fever, rash, cough, coryza, conjunctivitis, otitis media, and diarrhea who received a positive test result for measles by real-time reverse transcription-polymerase chain reaction (RT-PCR). Six additional children who attended the same child care facility and the grandfather of one of the children were confirmed by RT-PCR testing to have measles. None of the patients was reported to have traveled. LPH contacted the pediatric patients' caregivers to conduct case investigations and provided recommendations to the child care facility for home isolation, vaccination, and testing. LPH also communicated with caregivers, other child care facilities in the area, and the public to raise awareness. The child care facility implemented measures to minimize transmission, including separating children who were not yet eligible for the measles, mumps, and rubella vaccine; minimizing the use of shared spaces; and monitoring signs and symptoms. Collaboration between public health and community partners such as child care facilities can facilitate a rapid response and control of infectious disease outbreaks.

Measles is a highly infectious febrile rash illness and was declared eliminated in the United States in 2000. However, measles importations continue to occur, and U.S. measles elimination status was threatened in 2019 as the result of two prolonged outbreaks among undervaccinated communities in New York and New York City. To assess U.S. measles elimination status after the 2019 outbreaks and to provide context to understand more recent increases in measles cases, CDC analyzed epidemiologic and laboratory surveillance data and the performance of the U.S. measles surveillance system after these outbreaks. During January 1, 2020-March 28, 2024, CDC was notified of 338 confirmed measles cases; 97 (29%) of these cases occurred during the first quarter of 2024, representing a more than seventeenfold increase over the mean number of cases reported during the first quarter of 2020-2023. Among the 338 reported cases, the median patient age was 3 years (range = 0-64 years); 309 (91%) patients were unvaccinated or had unknown vaccination status, and 336 case investigations included information on >= 80% of critical surveillance indicators. During 2020-2023, the longest transmission chain lasted 63 days. As of the end of 2023, because of the absence of sustained measles virus transmission for 12 consecutive months in the presence of a well -performing surveillance system, U.S. measles elimination status was maintained. Risk for widespread U.S. measles transmission remains low because of high population immunity. However, because of the increase in cases during the first quarter of 2024, additional activities are needed to increase U.S. routine measles, mumps, and rubella vaccination coverage, especially among close-knit and undervaccinated communities. These activities include encouraging vaccination before international travel and rapidly investigating suspected measles cases.

INTRODUCTION:Testing for immunity to measles, mumps, and rubella should include only immunoglobulin G (IgG); immunoglobulin M (IgM) testing is appropriate only if acute illness is suspected. The appropriateness of measles, mumps, and rubella IgM testing was evaluated in a national administrative dataset. METHODS:Laboratory testing for measles, mumps, and rubella during 2019-2022 was analyzed in 2024 using HealthVerity administrative claims and laboratory data. IgG, IgM, and reverse-transcriptase polymerase chain reaction (RT-PCR) testing are described by year, demographics, and region. IgM testing was examined for appropriateness, defined as an IgM test combined with diagnostic codes indicative of acute illness. RESULTS:During 2019-2022, IgM testing represented a small proportion of serologic testing (measles: 3.3%, mumps: 2.4%, rubella: 2.1%) but appeared to be appropriately performed in only 15.4% of cases for measles, 32.8% of cases for mumps, and 10.2% of cases for rubella. IgM testing was more commonly performed for female patients, with the largest discrepancy seen for rubella (90.5% female vs 9.5% male). IgM for measles and mumps was more often performed appropriately for persons aged 0-19 years (37.6% and 60.1%) compared with persons aged 20-49 years (11.8% and 22.0%) and 50+ years (16.5% and 33.8%). CONCLUSIONS:The majority of IgM testing for measles, mumps, and rubella during this period appeared inappropriate. Clinicians and health systems could ensure that IgG testing alone is performed when evaluating for immunity through modifications to electronic medical records and commercial laboratories could ensure that providers are able to test for IgG alone when evaluating immunity.

Objective: To describe maternal demographics and compare clinical characteristics of infants with congenital cytomegalovirus (cCMV) identified through diagnostic codes and laboratory data in the United States during 2018-2023. Methods: We used a CDC-licensed subset of HealthVerity data, which contained linked pregnant people-infant claims data from publicly and privately insured individuals during 2018-2023 (2023 Quarter 3 HealthVerity Maternal Outcomes Masterset data). We identified infants with cCMV using diagnostic codes or positive laboratory test results within 45 days of birth. Results: Among 744 (4.6 per 10,000 live births) infants with cCMV during 2018-2023, 599 (81%) were identified by a diagnostic code only. Among 732 linked pregnant people, 91 (12%) had a diagnosis of CMV infection during pregnancy, with a similar distribution by age group and insurance type, but a lower proportion were Black as compared to those without CMV infection during pregnancy (14% vs. 29%, respectively). Overall, 452 (61%) infants had >= 1 cCMV-related clinical sign at birth and 185 (25%) had valganciclovir prescriptions. Eighty-eight (68%) infants identified by a positive laboratory test only had no cCMV-related signs and none had valganciclovir prescriptions. Conclusions: Using healthcare claims data, we found a minimal overlap of cCMV identified by diagnostic codes and laboratory test results. A minority of linked pregnant people with infants with cCMV had a CMV diagnosis during pregnancy. cCMV surveillance will help better understand the validity of ICD codes to identify infants with cCMV, describe the spectrum of disease, and monitor the use of antivirals.

During October 2021-June 2023, a total of 392 cases of acute hepatitis of unknown etiology in children in the United States were reported to Centers for Disease Control and Prevention as part of national surveillance. We describe demographic and clinical characteristics, including potential involvement of adenovirus in development of acute hepatitis, of 8 fatally ill children who met reporting criteria. The children had diverse courses of illness. Two children were immunocompromised when initially brought for care. Four children tested positive for adenovirus in multiple specimen types, including 2 for whom typing was completed. One adenovirus-positive child had no known underlying conditions, supporting a potential relationship between adenovirus and acute hepatitis in previously healthy children. Our findings emphasize the importance of continued investigation to determine the mechanism of liver injury and appropriate treatment. Testing for adenovirus in similar cases could elucidate the role of the virus.

BACKGROUND In July 2022, New York State (NYS) reported a case of paralytic polio in an unvaccinated young adult, and subsequent wastewater surveillance confirmed sustained local transmission of type 2 vaccine-derived poliovirus (VDPV2) in NYS with genetic linkage to the paralyzed patient. METHODS We adapted an established poliovirus transmission and oral poliovirus vaccine (OPV) evolution model to characterize dynamics of poliovirus transmission in NYS, including consideration of the immunization activities performed as part of the declared state of emergency. RESULTS Despite sustained transmission of imported VDPV2 in NYS involving potentially thousands of individuals (depending on seasonality, population structure and mixing assumptions) in 2022, the expected number of additional paralytic cases in years 2023 and beyond is small (less than 0.5). However, continued transmission and/or reintroduction of poliovirus into NYS and other populations remains a possible risk in communities that do not achieve and maintain high immunization coverage. CONCLUSION In countries such as the US that use only inactivated poliovirus vaccine, even with high average immunization coverage, imported polioviruses may circulate and pose a small but non-zero risk of causing paralysis in non-immune individuals.

Multiple factors may influence parental vaccine hesitancy towards pediatric COVID-19 vaccines and routine childhood immunizations (RCIs). Using the United States National Immunization Survey-Child COVID Module data collected from parents/guardians of children aged 5-11 years, this cross-sectional study (1) identified the trends and prevalence estimates of parental hesitancy towards pediatric COVID-19 vaccines and RCIs, (2) examined the relationship between hesitancy towards pediatric COVID-19 vaccines and RCIs, and (3) assessed trends in parental hesitancy towards RCIs by sociodemographic characteristics and behavioral and social drivers of COVID-19 vaccination. From November 2021 to July 2022, 54,329 parents or guardians were interviewed. During this 9-month period, the proportion of parents hesitant about pediatric COVID-19 vaccines increased by 15.8 percentage points (24.8% to 40.6%). Additionally, the proportion of parents who reported RCIs hesitancy increased by 4.7 percentage points from November 2021 to May 2022 but returned to baseline by July 2022. Over nine months, parents' concerns about pediatric COVID-19 infections declined; however, parents were increasingly worried about pediatric COVID-19 vaccine safety and overall importance. Furthermore, pediatric COVID-19 vaccine hesitancy was more prevalent among parents of children who were White (43.2%) versus Black (29.3%) or Hispanic (26.9%) and those residing in rural (51.3%) compared to urban (28.9%) areas. In contrast, RCIs hesitancy was higher among parents of children who were Black (32.0%) versus Hispanic (24.5%) or White (23.6%). Pediatric COVID-19 vaccine hesitancy was 2-6 times as prevalent among parents who were RCIs hesitant compared to those who were RCIs non-hesitant. This positive correlation between parental hesitancy towards pediatric COVID-19 vaccines and RCIs was observed for all demographic and psychosocial factors for unadjusted and adjusted prevalence ratios. Parent-provider interactions should increase vaccine confidence, shape social norms, and facilitate behavior change to promote pediatric vaccination rates.

On April 24, 2023, the American Samoa Department of Health (ASDoH) declared a public health emergency amid concern about a possible measles outbreak given low 2-dose vaccination coverage at the time. ASDoH had received two positive measles immunoglobulin (Ig) M test results after Flag Day festivities 1 week earlier from vaccinated children. ASDoH performed active case finding, took actions to mitigate transmission, and requested technical assistance from CDC. ASDoH implemented a vaccination campaign to improve suboptimal coverage. Confirmatory molecular testing of specimens from these initial persons under investigation (PUIs) was not possible, but subsequent testing of specimens from additional PUIs by Hawaii State Laboratories Division and CDC ruled out measles. In settings with low measles prevalence, measles antibody testing results have low positive predictive value and can lead to difficulties with interpreting results. Testing for additional pathogens revealed a variety of viruses known to cause common childhood viral exanthems. Both molecular and serologic testing should be performed for all suspected measles cases. To decrease the probability of false-positive IgM results, testing should be reserved for cases that meet the Council of State and Territorial Epidemiologists measles case definition, especially those in persons with no evidence of immunity and with a history of recent international travel. In addition, maintaining high measles vaccination coverage can prevent future outbreaks.

Background. A third dose of measles-mumps-rubella vaccine (MMR) may be administered for various reasons, but data on long-term immunity are limited. We assessed neutralizing antibody levels against measles and rubella among adults up to 11 years after receipt of a third MMR dose.Methods. In this longitudinal study, healthy adults who received a third MMR dose as young adults (ages 18-28 years) were recalled around 5 years and 9-11 years after the third dose. Measles and rubella antibody levels were assessed by plaque-reduction and immunocolorimetric neutralization assays, respectively. Antibody concentrations <120 mIU/mL and <10 U/mL were considered potentially susceptible to measles and rubella, respectively. Geometric mean concentrations (GMCs) and 95% confidence intervals (CIs) over time were estimated from generalized estimating equation models.Results. Approximately 5 and 9-11 years after receipt of the third dose, 405 and 304 adults were assessed, respectively. Measles GMC was 428 mIU/mL (95% CI, 392-468 mIU/mL) 5 years postvaccination, declining to 381 mIU/mL (95% CI, 339-428 mIU/mL) 11 years postvaccination. At the last follow-up visit (9-11 years postvaccination), 10% of participants were potentially susceptible to measles infection. Rubella GMCs were stable throughout the follow-up period (63 U/mL to 65 U/mL); none of the participants was susceptible to rubella at the last follow-up visit.Conclusions. Eleven years after receiving a third MMR dose, measles and rubella neutralizing antibody levels remained high in adults. However, on the basis of waning antibody levels, some adults may become susceptible to measles infection over time despite receipt of 3 vaccine doses.

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.

Synopsis Valacyclovir use in 10% of pregnancies with cytomegalovirus infection in this US cohort was likely for genital herpes treatment.

Measles and rubella are vaccine-preventable viral diseases and can be prevented by safe, highly effective vaccination with measles- and rubella-containing vaccines. Given the myriad causes of febrile exanthems, laboratory surveillance for both measles and rubella is important to document the incidence of these diseases and to track the progress and maintenance of elimination in near- and post-elimination settings. Diagnostic challenges can hinder effective surveillance and classification challenges can hinder efforts to demonstrate achievement or maintenance of elimination. In this report, we review diagnostic and classification challenges for measles and rubella in near- and post-elimination settings.

Background. Despite high vaccine effectiveness, wild-type measles can occur in previously vaccinated persons. We compared the clinical presentation and disease severity of measles by vaccination status and age in the postelimination era in the United States. Methods. We included U.S. measles cases reported from 2001 to 2022. Breakthrough measles was defined as cases with >= 1 documented dose of measles-containing vaccine, classic measles as the presence of rash, fever, and >= 1 symptoms (cough, coryza, or conjunctivitis), and severe disease as the presence of pneumonia, encephalitis, hospitalization, or death. Vaccinated cases with low- and high-avidity immunoglobulin G were classified as primary (PVF) and secondary (SVF) vaccine failures, respectively. Results. Among 4056 confirmed measles cases, 2799 (69%) were unvaccinated, 475 (12%) were breakthrough infections, and 782 (19%) had unknown vaccination; 1526 (38%), 1174 (29%), and 1355 (33%) were aged <5, 5-19, and >= 20 years, respectively. We observed a general decline in classic presentation and severe disease with an increase in the number of doses and fewer complications among children aged 5-19 years compared to other age groups. Among 93 breakthrough cases with avidity results, 11 (12%) and 76 (82%) were classified as PVF and SVF, respectively, with a higher proportion of PVFs having a classic measles presentation and severe disease than SVFs. Discussion. Breakthrough measles cases tended to have milder disease with less complications. A small proportion of breakthrough infections were due to PVF than SVF. It is critical to maintain high measles-mumps-rubella vaccination coverage in the United States to prevent serious measles illnesses. During the U.S. measles postelimination period, 11% of measles cases were among vaccinated persons. Breakthrough cases had milder disease and fewer complications; 82% were secondary vaccine failures. Children aged 5-19 years had fewer complications compared with older and younger age groups.

To assess demographics and outcomes up to 3 years of age among children with cytomegalovirus (CMV) infection in California neonatal intensive care units (NICUs) during 2010–2021.

Background On Aug 29, 2021, Operation Allies Welcome (OAW) was established to support the resettlement of more than 80 000 Afghan evacuees in the USA. After identification of measles among evacuees, incoming evacuee flights were temporarily paused, and mass measles vaccination of evacuees aged 6 months or older was introduced domestically and overseas, with a 21-day quarantine period after vaccination. We aimed to evaluate patterns of measles virus transmission during this outbreak and the impact of control measures. Methods We conducted a measles outbreak investigation among Afghan evacuees who were resettled in the USA as part of OAW. Patients with measles were defined as individuals with an acute febrile rash illness between Aug 29, 2021, and Nov 26, 2021, and either laboratory confirmation of infection or epidemiological link to a patient with measles with laboratory confirmation. We analysed the demographics and clinical characteristics of patients with measles and used epidemiological information and whole-genome sequencing to track transmission pathways. A transmission model was used to evaluate the effects of vaccination and other interventions. Findings 47 people with measles (attack rate: 0 center dot 65 per 1000 evacuees) were reported in six US locations housing evacuees in four states. The median age of patients was 1 year (range 0-26); 33 (70%) were younger than 5 years. The age distribution shifted during the outbreak towards infants younger than 12 months. 20 (43%) patients with wildtype measles virus had rash onset after vaccination. No fatalities or community spread were identified, nor further importations after flight resumption. In a non-intervention scenario, transmission models estimated that a median of 5506 cases (IQR 10-5626) could have occurred. Infection clusters based on epidemiological criteria could be delineated into smaller clusters using phylogenetic analyses; however, sequences with few substitution count differences did not always indicate single lines of transmission. Interpretation Implementation of control measures limited measles transmission during OAW. Our findings highlight the importance of integration between epidemiological and genetic information in discerning between individual lines of transmission in an elimination setting. Funding US Centers for Disease Control and Prevention. Copyright (c) 2023 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 license.