Measles Cases Surge in the United States: 4,410 Confirmed Cases Reported in 2026
The CDC reported 4,410 confirmed measles cases in the United States as of October 15, 2026 - nearly twice the total for all of 2025. With 96% of cases associated with outbreaks and kindergarten MMR coverage down to 92.4%, the resurgence highlights the consequences of gaps in community immunity. Early recognition, appropriate infection-control precautions, and maintaining vaccination coverage remain critical to preventing further spread.
Summary
PUBLIC HEALTH ALERT
Updated October 17, 2026 | Source: US Centers for Disease Control and Prevention (CDC)
[Posted 19/Oct/2026]
AUDIENCE: Infectious Disease, Internal Medicine
Key Surveillance Findings: According to the CDC, 4,410 confirmed measles cases were reported in the United States during 2026 as of October 15. Cases were reported across 47 jurisdictions, with 18 cases involving international visitors. The CDC recorded 42 new outbreaks during the year, and 96% of confirmed cases (4,228 of 4,410) were associated with outbreaks. This total includes cases linked to outbreaks that began in both 2025 and 2026.
The contrast with earlier years is marked. The United States reported 285 cases in 2024 and 2,289 in 2025. The current 2026 total reflects a significant increase in transmission and underscores the vulnerability of communities with inadequate immunization coverage.
Backround: The United States is experiencing a substantial resurgence of measles, with 4,410 confirmed cases reported as of October 15, 2026. The total has already exceeded the 2,289 cases recorded throughout 2025 by approximately 93%, highlighting the ongoing challenge of controlling a highly contagious, vaccine-preventable infection.
Declining Vaccination Coverage Raises Concern: Measles was declared eliminated in the United States in 2000, meaning sustained endemic transmission had been interrupted. However, imported infections can trigger outbreaks when the virus reaches susceptible populations.
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National measles, mumps, and rubella (MMR) vaccination coverage among kindergarteners declined from 95.2% during the 2019-2020 school year to 92.4% in 2025-2026. The CDC estimates that approximately 280,000 kindergarteners were at risk during the 2025-2026 school year. Because measles spreads exceptionally efficiently, clusters of unvaccinated individuals can sustain transmission even in areas where overall vaccination coverage appears relatively high.
Two doses of MMR vaccine are approximately 97% effective against measles, compared with 93% effectiveness after one dose. Maintaining high coverage and identifying susceptible individuals remain central to preventing further spread.
Clinical and Public Health Implications
Clinicians should remain alert to possible measles in patients with compatible symptoms, particularly when there is a history of travel, known exposure, or residence in an affected community. Measles can cause serious complications, especially in infants and young children. Suspected cases require prompt infection-control precautions and coordination with public health authorities; patients should not be directed into routine waiting areas where others may be exposed.
Healthcare professionals should review patients’ immunization histories, recommend vaccination in accordance with current guidance, and reinforce the importance of protection before international travel. Public health teams should continue surveillance, contact tracing, and targeted vaccination efforts in communities with low coverage.
Key Takeaway
The rise to more than 4,400 confirmed cases in 2026 demonstrates that measles elimination does not eliminate the risk of renewed outbreaks. Sustained vaccination coverage, rapid recognition of suspected cases, and coordinated public health action are essential to limit transmission and protect vulnerable populations.
Data note: CDC surveillance figures are provisional and include confirmed cases reported by jurisdictions as of noon on Thursday, October 15, 2026. Counts may change as additional cases are confirmed. An outbreak is defined by the CDC as three or more related cases.
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Source: US Centers for Disease Control and Prevention. Measles Cases and Outbreaks. Updated October 16, 2026. CDC.
Aztreonam/Avibactam Retains Activity Against Drug-Resistant Enterobacterales
An analysis of 80,927 Enterobacterales isolates from 103 US medical centers found that aztreonam/avibactam retained in vitro activity against 98.1% of carbapenem-resistant isolates and 98.4% of metallo-beta-lactamase producers. Meanwhile, MBLs were identified in 36.1% of CRE isolates collected during 2023–2024. These findings highlight the potential value of aztreonam/avibactam against resistant Gram-negative bacteria and the need for continued antimicrobial resistance surveillance.
KEY FINDINGS: Aztreonam/avibactam retained substantial in vitro activity against Enterobacterales resistant to other advanced beta-lactam/beta-lactamase inhibitor combinations, including MBL-producing organisms. The findings are particularly relevant as NDM and other MBLs increasingly complicate the treatment of CRE infections. These results support the potential role of aztreonam/avibactam as a treatment option for selected infections caused by resistant Gram-negative bacteria. However, laboratory susceptibility findings do not establish clinical effectiveness in individual patients. Treatment decisions should incorporate susceptibility testing, infection site, patient factors, and applicable clinical guidance. Continued surveillance is also necessary to monitor emerging resistance.
BACKGROUND: Carbapenem-resistant Enterobacterales (CRE) are an increasing clinical concern because resistance to newer antibiotics, including ceftazidime/avibactam and meropenem/vaborbactam, limits treatment options for serious infections. Metallo-beta-lactamase (MBL)-producing organisms pose a particular challenge because these enzymes can inactivate many beta-lactam antibiotics. Aztreonam/avibactam combines aztreonam's stability against MBL-mediated hydrolysis with avibactam's inhibition of several other beta-lactamases. This study assessed its in vitro activity against resistant Enterobacterales collected from US medical centers.
DETAILS: Investigators analyzed 80,927 Enterobacterales isolates collected from 103 US medical centers between 2016 and 2024, with one isolate per patient. Antimicrobial susceptibility was evaluated using broth microdilution. The analysis focused on isolates that were not susceptible to ceftazidime/avibactam, meropenem/vaborbactam, or both, as well as carbapenem-resistant and MBL-producing isolates. Whole-genome sequencing was used to identify carbapenemase genes in resistant isolates. Among the collected isolates, 194 (0.24%) were not susceptible to ceftazidime/avibactam or meropenem/vaborbactam, 115 (0.14%) were not susceptible to both combinations, and 832 (1.0%) were carbapenem resistant.
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Aztreonam/avibactam demonstrated activity against 91.9% of ceftazidime/avibactam-nonsusceptible isolates and 94.0% of meropenem/vaborbactam-nonsusceptible isolates. Activity was observed against 98.1% of CRE isolates and 98.4% of MBL-producing isolates. Cefiderocol was active against 78.8% of ceftazidime/avibactam-nonsusceptible isolates, 83.2% of meropenem/vaborbactam-nonsusceptible isolates, 94.7% of CRE isolates, and 82.1% of MBL producers. Genetic analysis identified carbapenemase genes in 159 (82.0%) of isolates nonsusceptible to ceftazidime/avibactam or meropenem/vaborbactam and in 683 (80.1%) of CRE isolates. New Delhi metallo-beta-lactamase (NDM) was the most common carbapenemase among the resistant isolates, identified in 114 (58.8%). Notably, MBL-producing organisms accounted for 36.1% (73/202) of CRE isolates collected during 2023–2024, highlighting the importance of continued resistance surveillance.
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Source: Sader, H. S., Papp-Wallace, K. M., Kimbrough, J. H., et al. Antimicrobial activity of aztreonam/avibactam and molecular characterization of Enterobacterales not susceptible to ceftazidime/avibactam and/or meropenem/vaborbactam from US medical centres (2016-2024). Journal of Antimicrobial Chemotherapy. 2026; 81(10). Published: October, 2026. DOI: 10.1093/jac/dkag308.
Increased Use of Adjunctive Azithromycin After Unscheduled Cesarean Delivery Associated With Lower Postpartum Infection Rates Background
A US analysis of 1.66 million deliveries found that adjunctive azithromycin use during cesarean delivery increased from 2.2% before 2016 to 39.6% during 2017–2024. Over the same period, postpartum infection after cesarean delivery declined from 9.2% to 8.0%. The findings suggest that evidence from the 2016 clinical trial was followed by substantial adoption in routine practice and lower postpartum infection rates.
KEY FINDINGS: In this large US observational analysis, publication of randomized trial evidence in 2016 was followed by a substantial increase in adjunctive azithromycin use during unscheduled cesarean delivery and a relative reduction in postpartum infections. The study provides evidence that clinical trial findings were subsequently incorporated into routine practice beyond the original trial setting. Because this was an observational difference-in-differences analysis rather than a new randomized trial, the findings demonstrate an association between adoption of the intervention and changes in infection rates rather than establishing causality.
BACKGROUND: Unscheduled cesarean delivery is associated with a higher risk of postpartum infection. A 2016 clinical trial showed that adding azithromycin to standard antibiotic prophylaxis could reduce postoperative infections in patients undergoing unscheduled cesarean delivery. This study evaluated whether use of adjunctive azithromycin increased after publication of that trial and whether postpartum infection rates subsequently changed in routine US practice.
DETAILS: Investigators conducted a difference-in-differences analysis using Epic Cosmos data from 2013 through 2024. The analysis included pregnant individuals who received prenatal care, experienced labor, and delivered a live singleton infant at 24 to 43 weeks' gestation. Cesarean deliveries served as the treatment group and vaginal deliveries as the comparison group, allowing changes occurring after publication of the 2016 trial to be assessed relative to trends in vaginal births.
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The study included 1,663,441 deliveries, comprising 202,234 cesarean births and 1,461,207 vaginal births. The primary outcomes were perioperative azithromycin administration and postpartum infection occurring within 6 weeks of delivery. The investigators compared births from January 1, 2013, through September 28, 2016, with those occurring from January 1, 2017, through December 31, 2024.
Before publication of the 2016 trial, azithromycin was administered during 2.2% of cesarean births compared with 0.01% of vaginal births. During 2017-2024, use increased to 39.6% of cesarean births and 0.04% of vaginal births. The adjusted difference-in-differences estimate for cesarean births was 37.6 percentage points (95% CI, 33.1 to 42.2). Postpartum infection after cesarean delivery declined from 9.2% during the pre-2016 period to 8.0% during 2017-2024. Among vaginal births, infection rates changed from 2.0% to 2.7%, producing an adjusted difference-in-differences estimate of -2.0 percentage points (95% CI, -2.6 to -1.4) for cesarean births. The findings therefore showed that, following publication of the randomized trial, adjunctive azithromycin use increased substantially among patients undergoing unscheduled cesarean delivery while postpartum infection rates decreased relative to the comparison group.
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Source: Freret, T. S., Litman, E., Wen, T., et al. Adoption of Adjunctive Azithromycin for Unscheduled Cesarean Delivery and Postpartum Infections. JAMA. 2026; Published: September 14, 2026. DOI: 10.1001/jama.2026.15010.
Accounting for Long-Term Consequences of Tuberculosis Strengthens the Case for Preventive Screening in New Immigrants
A Canadian modeling study found that including long-term illness and mortality after tuberculosis more than doubled the estimated health benefits of postarrival TB screening and preventive treatment among new immigrants. Incorporating these consequences reduced the projected cost from $235,088 to $100,742 CAD per QALY gained. The findings highlight the importance of considering the long-term burden of TB when evaluating prevention strategies.
KEY FINDINGS: The analysis suggests that excluding long-term illness, mortality, and healthcare costs after TB treatment can substantially underestimate the health value of TB prevention. In the modeled Canadian immigrant population, incorporating these consequences more than doubled the estimated QALY benefit of postarrival TB infection screening and preventive treatment and reduced the estimated cost per QALY by more than half. However, the findings depend on assumptions about the long-term effects of TB, and the investigators noted that some underlying associations may include residual confounding and that post-TB illness estimates are less certain.
BACKGROUND: Tuberculosis prevention strategies are commonly evaluated by considering acute TB disease and death, while longer-term consequences after successful treatment may be overlooked. These consequences can include persistent illness, increased mortality, and additional healthcare utilization. This study assessed how incorporating these longer-term effects would change estimates of the health benefits and cost-effectiveness of postarrival TB infection screening and preventive treatment among people newly immigrating to Canada.
DETAILS: The investigators developed a Markov microsimulation model representing a hypothetical cohort of 400,000 people immigrating permanently to Canada in 2025. The analysis compared the existing postarrival TB infection screening level of 0.5% with a modeled screening strategy reaching 68% of eligible new immigrants. The intervention targeted new permanent residents from countries with annual TB incidence >50/100,000 persons; individuals testing positive for TB infection were assumed to receive 4 months of daily rifampin as preventive treatment. Outcomes were projected over 25 years and included TB episodes, TB deaths, quality-adjusted life-years (QALYs), and TB-related healthcare costs. The model incorporated three post-TB consequences: increased mortality after TB treatment, persistent illness or disability, and excess healthcare costs. A total of 2,000 probabilistic simulations were performed to account for uncertainty in model parameters.
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When only acute TB consequences were considered under the current screening scenario, the model projected 927 (95% UR 764-1,123) TB cases, 30 (95% UR 24-36) TB deaths, and 312 (95% UR 241-386) QALYs lost over 25 years. Adding post-TB death increased estimated QALYs lost by 1.6-fold, while including post-TB illness increased them by 1.5-fold. When all three long-term consequences were incorporated, TB was projected to account for 657 (95% UR 479-876) QALYs lost, a 2.1-fold increase compared with considering acute consequences alone.
The expanded screening and preventive-treatment strategy produced 2.4-fold greater estimated QALY gains (95% UR 1.6-4.4-fold) and 2.2-fold more TB deaths averted (95% UR 1.6-3.0-fold) when all post-TB consequences were included. The estimated incremental cost-effectiveness ratio decreased from $235,088 to $100,742 CAD per QALY gained. In the model incorporating all post-TB consequences, 53% of simulations fell below a willingness-to-pay threshold of $100,000 per QALY, compared with 8% when only acute TB consequences were considered.
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Source: Ainiwaer, A., Uppal, A., Schwartzman, K., et al. Posttuberculosis Consequences on Tuberculosis Prevention Effectiveness and Cost-effectiveness among New Immigrants, Canada. Emerging Infectious Diseases. 2026; 32(9): 1421-1429. Published: September, 2026. DOI: 10.3201/eid3209.260473.
Broad-Spectrum Antibiotic Use Is Lower Among Hospice Patients With Cancer at the End of Life
In this nationwide Korean cohort, hospice utilization was associated with lower broad-spectrum antibiotic use as death approached, particularly during the final week and final 3 days of life. The findings suggest that hospice involvement may be associated with a transition toward more selective antimicrobial use and less intensive treatment near the end of life. However, the study was observational, and causality cannot be established. Important clinical variables, including infection severity, microbiological findings, functional status, symptom burden, cancer stage, and treatment intent, were unavailable in the claims data.
KEY FINDINGS: Among adults with cancer approaching death, hospice utilization was associated with less frequent and lower-intensity broad-spectrum antibiotic exposure, particularly during the final days of life. The findings are consistent with a transition toward comfort-focused care, although they do not establish that hospice care itself caused the reduction. Hospice initiation occurred relatively close to death, with a mean interval of 39.9 days and a median of 22.0 days, and some antibiotic treatment may have preceded hospice enrollment. In addition, cancer stage, treatment status, infection severity, microbiological findings, functional status, symptom burden, and treatment intent were unavailable in the claims data.
BACKGROUND: Antibiotic treatment remains common during end-of-life care for patients with cancer, despite uncertain benefits for survival and potential burdens including drug toxicity, intravenous administration, adverse effects, and antimicrobial resistance. This retrospective cohort study evaluated whether hospice involvement was associated with differences in broad-spectrum antibiotic use among adults with cancer during the final 3 months of life.
DETAILS: Investigators analyzed Korean National Health Insurance Service claims data for adults aged ≥18 years who died between January 1, 2018, and December 31, 2021, with one of the 10 leading cancer-related causes of death. Hospice users had received inpatient, home-based, or consultation-based hospice care before death. Broad-spectrum antibiotic exposure included anti-pseudomonal penicillins, anti-pseudomonal cephalosporins, carbapenems, and glycopeptides. The final 90 days of life were divided into four intervals: 1–3 months before death, 1 week to 1 month before death, the final week, and the final 3 days. Antibiotic exposure was assessed by the proportion of patients receiving antibiotics and by days of therapy (DOT) per 1,000 patient-days. Propensity score matching was performed at a 1:2 ratio.
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After matching, 38,102 hospice users and 75,736 non-hospice users were analyzed. During the final 3 months of life, 74.6% of hospice users and 79.0% of non-hospice users received at least one broad-spectrum antibiotic (P0.001). Antibiotic use was initially slightly higher among hospice users during the period 1–3 months before death, at 34.0% versus 32.2% (P0.001), but became consistently lower among hospice users thereafter. From 1 week to 1 month before death, use was 31.1% versus 32.8%; during the final week, 11.3% versus 18.5%; and during the final 3 days, 4.8% versus 10.3% among hospice and non-hospice users, respectively (all P0.001).
Days of therapy per 1,000 patient-days were also consistently lower among hospice users, with the greatest differences occurring during the final week and final 3 days of life. Carbapenems and glycopeptides demonstrated particularly pronounced differences between the groups. In cancer-specific analyses, patients with hematologic malignancies had the highest overall antibiotic exposure, followed by those with pancreatobiliary and gastric cancers, while exposure was comparatively lower among patients with breast and liver cancers.
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Source: Jeung, Y. S., Kim, H. J., Yu, J., et al. Comparison of Broad-Spectrum Antibiotic Use According to Hospice Utilization Among Patients with Cancer at the End of Life in South Korea: A Nationwide Analysis. Journal of Hospice and Palliative Care. 2026; 29(2): 41-50. Published: June 1, 2026. DOI: 10.14475/jhpc.2026.29.2.41.
US Measles Cases Rise in 2026 as Outbreaks Continue Amid Declining MMR Coverage
US measles activity has increased substantially in 2026, with 2,465 confirmed cases and 38 new outbreaks reported as of August 6. Declining MMR coverage may increase community vulnerability to transmission. Maintaining high vaccination coverage remains central to preventing measles outbreaks and sustaining elimination.
KEY FINDINGS: As of August 6, 2026, the US had reported 2,465 confirmed measles cases and 38 new outbreaks, with 94% of cases outbreak-associated. The increase occurs alongside a decline in kindergarten MMR coverage to 92.5% in 2024-2025 from 95.2% in 2019-2020. CDC emphasizes that measles can spread rapidly in communities with lower vaccination coverage, while 2 doses of MMR vaccine provide 97% protection against measles.
BACKGROUND: Measles was officially eliminated in the United States in 2000 following widespread use of the measles, mumps, and rubella (MMR) vaccine. However, declining vaccination coverage and increasing global measles activity have increased opportunities for measles transmission following importation into the United States.
DETAILS: As of August 6, 2026, the Centers for Disease Control and Prevention (CDC) reported 2,465 confirmed measles cases in the United States in 2026. Of these, 2,449 cases were reported by 47 jurisdictions, while 16 cases occurred among international visitors to the United States. Thirty-eight new outbreaks had been reported during 2026.
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Overall, 94% of confirmed cases in 2026 (2,309 of 2,465) were associated with outbreaks, including 936 cases from outbreaks beginning in 2026 and 1,373 from outbreaks that began in 2025. For comparison, 2,289 confirmed cases and 48 outbreaks were reported during the full year of 2025; 90% of cases (2,066 of 2,289) were outbreak-associated.
CDC reports confirmed measles cases notified by jurisdictions as of noon on Thursdays. An outbreak is defined as 3 or more related cases. State and CDC counts may differ because jurisdictions update and publicly report their data on different schedules.
MMR vaccination coverage among US kindergartners declined from 95.2% during the 2019-2020 school year to 92.5% during the 2024-2025 school year, leaving approximately 286,000 kindergartners at risk during the 2024-2025 school year. CDC notes that communities with vaccination coverage below the 95% level are more vulnerable to measles outbreaks. The 2026 measles case count reported by CDC as of August 6, 2026, had already exceeded the total number of confirmed cases reported during all of 2025 (2,465 vs 2,289). The high proportion of outbreak-associated cases indicates sustained transmission within affected communities.
The burden of measles remains closely associated with vaccination status. CDC reports that 2 doses of MMR vaccine are 97% effective at preventing measles, while 1 dose is 93% effective. Breakthrough infections can occur, particularly during outbreaks with high levels of circulating measles virus, and account for approximately 10% of all measles infections.
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Source: CDC: Measles Cases and Outbreaks. Centers for Disease Control and Prevention (CDC). 2026; Published: August 7, 2026.
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