Pertussis Outbreak & Cases in US 2025 | Statistics & Facts

Pertussis Outbreak in America 2025

The United States is experiencing a significant resurgence of pertussis, commonly known as whooping cough, throughout 2025. This vaccine-preventable respiratory disease has returned to pre-pandemic levels with alarming velocity, marking one of the most substantial public health challenges in recent years. The Centers for Disease Control and Prevention reports that pertussis cases have increased dramatically compared to the historically low numbers observed during the COVID-19 pandemic, when mitigation measures like masking and social distancing inadvertently reduced transmission of this highly contagious bacterial infection.

The 2025 pertussis outbreak represents a concerning departure from the suppressed case counts witnessed between 2020 and 2023. Multiple factors have converged to fuel this resurgence, including declining childhood vaccination rates, waning immunity from previously administered vaccines, and the return to normal social interaction patterns following pandemic restrictions. With over 10,000 confirmed and probable cases reported by mid-year 2025, health officials across the nation are working urgently to contain outbreaks, protect vulnerable populations, and restore vaccination coverage to levels sufficient for community protection. The situation has prompted widespread public health alerts, intensified surveillance activities, and renewed emphasis on the critical importance of timely immunization for all age groups.

Key Facts About Pertussis Outbreak in the US 2025

Data Sources: CDC National Notifiable Diseases Surveillance System (NNDSS), CDC SchoolVaxView 2024-25, Washington State Department of Health Weekly Pertussis Update, Pan American Health Organization (PAHO) Epidemiological Alert May 2025, CDC 2024 Provisional Pertussis Surveillance Report

The data presented reveals the magnitude of the 2025 pertussis outbreak across the United States. With 10,062 confirmed and probable pertussis cases reported through the first 18 weeks of 2025, the nation is witnessing infection rates approximately four times higher than the same period in 2023. This dramatic increase has resulted in 5 confirmed deaths, underscoring the life-threatening nature of this respiratory illness, particularly for the youngest and most vulnerable populations. The geographic distribution shows concentration in western states, with Washington State leading nationally at 1,980 cases through Week 44, followed by Oregon with 723 cases and California with 590 cases.

The vaccination landscape reveals troubling declines that directly correlate with the outbreak’s severity. Kindergarten DTaP vaccination coverage has fallen to 92.1% for the 2024-25 school year, representing a significant drop from the 95% coverage achieved in 2019-20 before the pandemic. Simultaneously, vaccine exemptions have reached an unprecedented high of 3.6%, with approximately 138,000 kindergartners attending school without complete vaccination documentation. The infant population faces the greatest risk, with Washington State reporting an incidence rate of 207.7 cases per 100,000 infants under one year of age. Experts project that if current transmission patterns persist, the United States could experience approximately 70,000 pertussis cases by the end of 2025, potentially making it one of the worst years for whooping cough since the introduction of widespread vaccination in the 1940s.

Pertussis Cases by State in the US 2025

Data Source: CDC 2024 Provisional Pertussis Surveillance Report (January 2025)

The state-by-state breakdown of pertussis cases in 2024 provides critical insights into the geographic distribution of the outbreak that continued into 2025. Alaska reported the highest incidence rate at 81.11 cases per 100,000 population, despite having 595 total cases, demonstrating how smaller population states can experience disproportionate disease burden. Idaho followed with an incidence rate of 54.10 per 100,000 and 1,049 cases, while Illinois recorded the second-highest absolute case count nationwide with 2,304 cases and an incidence rate of 18.31 per 100,000. The data reveals significant regional variation, with western and midwestern states bearing a heavier disease burden compared to southern states.

States with lower incidence rates include Georgia at 2.58 per 100,000 with 280 cases, Louisiana at 2.81 per 100,000 with 129 cases, and District of Columbia at 3.27 per 100,000 with 22 cases. However, these lower rates don’t diminish the public health significance, as even states with relatively fewer cases experienced significant increases compared to 2023 levels. California, despite having one of the lower incidence rates at 4.55 per 100,000, reported 1,775 cases in absolute numbers, reflecting the state’s large population. The variation in case counts and incidence rates across states reflects differences in vaccination coverage, population density, disease surveillance capabilities, and the timing of local outbreak peaks throughout the year.

Pertussis Deaths and Mortality Rates in the US 2025

Data Source: CDC 2024 Provisional Pertussis Surveillance Report (January 2025)

The mortality data from 2024 carried significant implications for the 2025 outbreak, revealing the deadly nature of pertussis for the youngest Americans. Ten deaths were reported in 2024, with 6 fatalities occurring in infants under one year of age, representing 60% of all pertussis-related deaths. The remaining 4 deaths affected individuals over one year old. By early 2025, additional deaths were confirmed, including two infants in Louisiana who died within a six-month period and a child under age 5 in Washington State who died in late 2024. Through the first 18 weeks of 2025, the CDC and Pan American Health Organization documented 5 additional deaths nationwide.

The concentration of deaths among infants under one year highlights a critical vulnerability period. These youngest patients cannot receive their first DTaP vaccine until they reach 2 months of age, leaving them completely unprotected during their first weeks of life. Health officials emphasize that approximately 70% of all pertussis deaths occur in newborns under 2 months old. The mortality rate among hospitalized infants remains concerning, with approximately 1% of infected infants dying from complications such as pneumonia, seizures, encephalopathy, or respiratory failure. The 2025 outbreak has intensified focus on maternal vaccination during pregnancy, as this strategy provides passive immunity to newborns through antibody transfer. However, declining maternal vaccination rates and increasing vaccine hesitancy have left more infants vulnerable to this preventable yet potentially fatal disease.

Pertussis Vaccination Coverage Among Children in the US 2025

Data Source: CDC SchoolVaxView 2024-25 School Year Report, CDC 2024 Provisional Pertussis Surveillance Report

The vaccination coverage data for 2025 reveals a troubling erosion in the protective barrier against pertussis outbreaks. Kindergarten DTaP vaccination coverage declined to 92.1% for the 2024-25 school year, down from 95% in the 2019-20 pre-pandemic period. This 2.9 percentage point decline translates to thousands of unprotected children entering schools across America. While coverage among younger children aged 19-35 months remains above 95% for at least 3 doses of DTaP, the drop in kindergarten coverage suggests that completion of the full vaccine series and timely booster doses have become problematic.

The exemption data provides crucial context for understanding declining vaccination rates. Vaccine exemptions reached an all-time high of 3.6% among kindergartners in 2024-25, meaning approximately 138,000 children are attending school without full vaccination. Non-medical exemptions account for the overwhelming majority at 3.4%, representing a 54.5% increase from the 2.2% rate in 2019-20. Meanwhile, medical exemptions actually decreased slightly from 0.3% to 0.2%. This pattern indicates that the rise in exemptions stems primarily from parental choice rather than medical contraindications. State-level variation is substantial, with Idaho reporting the lowest DTaP coverage at 78.3% and the highest exemption rate at approximately 15% for at least one vaccine, while Connecticut and Virginia achieved the highest coverage at 98.2% each. The gap between current coverage levels and the 95% threshold needed for community immunity directly contributes to the ongoing pertussis outbreak in 2025.

Pertussis Cases by Age Group in the US 2025

Data Source: CDC 2024 Provisional Pertussis Surveillance Report (January 2025)

The age-stratified case data from 2024 illustrates which populations bore the greatest burden as the outbreak accelerated into 2025. Children aged 1-4 years accounted for the majority of cases with 4,806 infections, representing 62.5% of all cases in the analyzed age groups. This concentration reflects the high exposure risk in childcare and preschool settings where respiratory diseases transmit readily. Infants aged 6-11 months experienced 1,150 cases (15.0%), the age group facing the highest risk of severe complications requiring hospitalization. Children aged 5-6 years contributed 1,733 cases (22.5%), primarily school-aged children in kindergarten and early elementary grades.

The vaccination status breakdown reveals critical insights into pertussis transmission patterns. Among infants 6-11 months old, 67.3% had unknown vaccination status, 7.3% were confirmed unvaccinated, and only 16.4% had received partial vaccination. For children 1-4 years, 25.6% had completed their primary DTaP series with 3 or more doses, yet still contracted pertussis, demonstrating that waning vaccine immunity contributes significantly to disease spread. Among 5-6 year olds, 33.0% with completed vaccination series still developed illness. These data underscore that while unvaccinated children face higher risk of severe disease, even vaccinated children can contract and transmit pertussis as vaccine-induced immunity wanes over time. The CDC emphasizes that protection from DTaP diminishes progressively, necessitating booster doses and explaining why vaccinated populations still contribute to outbreak dynamics in 2025.

Pertussis Outbreak Trends: 2023 vs 2024 vs 2025 in the US

Data Sources: CDC Pertussis Cases by Year (1922-2023), CDC 2024 Provisional Report, PAHO May 2025 Alert, Expert Projections

The multi-year comparison starkly illustrates the dramatic resurgence of pertussis in the United States. 2023 represented a continuation of pandemic-suppressed case counts with approximately 7,063 cases for the entire year. 2024 marked a watershed moment as cases exploded to more than 35,000, representing a sixfold increase over the previous year and signaling a return to typical pre-pandemic transmission patterns. This dramatic surge established 2024 as having the highest annual case count in over a decade, with 10 confirmed deaths.

2025 has continued this alarming trajectory with even greater intensity. By the end of the first quarter (Week 18), the nation had already recorded 10,062 confirmed and probable cases, tracking at four times the pace observed during the same period in 2024. If this rate persists, epidemiological models project approximately 70,000 cases by December 2025, which would represent the highest annual total since 1950 and potentially mark the worst year for whooping cough since the introduction of effective vaccines in the 1940s. The CDC reported that cases peaked in November 2024 and have been trending downward since, yet remain substantially elevated compared to pre-pandemic baseline levels. Multiple states are experiencing their highest case totals in a decade, with outbreaks documented from Louisiana to South Dakota to Idaho, demonstrating that the 2025 surge is not regionally confined but represents a nationwide public health emergency.

State-Level Pertussis Incidence Rates in the US 2025

Data Source: CDC 2024 Provisional Pertussis Surveillance Report (January 2025)

The incidence rate analysis reveals dramatic geographic disparities in pertussis outbreak severity across the United States entering 2025. Alaska experienced the most severe burden with 81.11 cases per 100,000 population, more than 31 times higher than Georgia’s rate of 2.58 per 100,000. This extreme variation reflects differences in population density, vaccination coverage, outbreak detection and response capabilities, and community immunity levels. Idaho reported the second-highest incidence at 54.10 per 100,000, correlating directly with the state’s lowest kindergarten DTaP coverage rate of 78.3% and highest exemption rate approaching 15%.

States in the “high” category—Illinois (18.31), Maine (12.85), and Massachusetts (12.05)—experienced sustained community transmission requiring intensive public health interventions. The “moderate” category includes states like Colorado (11.22), Iowa (11.03), Kentucky (10.44), Arizona (10.35), and Arkansas (9.82), all facing elevated disease burden above typical endemic levels. Meanwhile, larger population states like California (4.55), Florida (3.29), and Georgia (2.58) maintained lower incidence rates despite reporting substantial absolute case numbers. The data demonstrates that smaller states with concentrated outbreaks and lower vaccination coverage face disproportionate public health challenges. These geographic patterns informed targeted public health responses in 2025, with states experiencing the highest incidence rates receiving additional CDC support for outbreak investigation, contact tracing, and vaccination promotion campaigns.

Pertussis Among Infants in the US 2025

Data Sources: Washington State Department of Health Weekly Pertussis Update (Week 44, 2025), CDC Reports

The infant data from 2025 reveals the devastating impact of pertussis on the youngest Americans. Washington State documented an infant incidence rate of 207.7 cases per 100,000 among children under one year old, representing a rate more than 8 times higher than the general population rate of 24.6 per 100,000. Through Week 44, 169 infants in Washington contracted pertussis, with 153 being old enough to have received at least their first vaccine dose. Alarmingly, only 42 of these eligible infants (27.5%) had received even a single dose of DTaP, leaving the vast majority completely unprotected.

The clinical consequences for infected infants are severe. Approximately one in three babies with pertussis requires hospitalization, where one in five develops pneumonia as a complication. The mortality data is particularly tragic: approximately 1% of infected infants die from the disease, with 70% of all pertussis deaths occurring in newborns under 2 months of age—before they’re eligible for vaccination. The 2025 outbreak saw multiple infant deaths, including two in Louisiana within a six-month period and a child under age 5 in Washington State. These deaths were preventable through maternal vaccination during pregnancy, which transfers protective antibodies to the fetus. However, declining maternal Tdap vaccination rates have left increasing numbers of newborns vulnerable. Public health officials emphasize that protecting infants requires a two-pronged approach: vaccinating pregnant women during every pregnancy and ensuring all close contacts of newborns are fully vaccinated—a strategy complicated by rising vaccine hesitancy and exemption rates documented throughout 2025.

Regional Distribution of Pertussis Cases in the US 2025

Data Sources: CDC 2024 Provisional Report, Washington State DOH, PAHO May 2025 Alert

The regional analysis of pertussis cases in 2025 reveals distinct geographic patterns of disease distribution across the United States. The West Coast emerged as the national epicenter, accounting for over 3,293 cases through mid-year across just three states. Washington State alone reported 1,980 cases by Week 44, the highest state total nationally, followed by Oregon with 723 cases and California with 590 cases. This concentration reflects sustained community transmission, large population centers with pockets of low vaccination coverage, and robust surveillance systems capable of detecting cases.

The Midwest represented the second major outbreak region with over 3,681 documented cases. Illinois reported 2,304 cases, the second-highest state total nationally, while Michigan (537), Ohio (494), and Wisconsin (346) all experienced significant disease burden. The Mountain West region, comprising Idaho (1,049 cases), Colorado (655), and Arizona (762), totaled over 2,466 cases and correlated closely with states reporting the lowest kindergarten vaccination coverage rates. Idaho, with kindergarten DTaP coverage at just 78.3%, experienced one of the highest per-capita outbreak rates. The South showed more variable patterns, with Florida reporting 732 cases but lower per-capita incidence, while Louisiana (129 cases) experienced concentrated outbreaks resulting in two infant deaths. The Northeast maintained moderate sustained transmission exceeding 1,305 cases, with Massachusetts leading the region at 841 cases. These regional patterns informed targeted federal and state public health interventions throughout 2025, focusing resources on areas with the highest disease burden and lowest vaccination coverage.

Pertussis Vaccination Schedule and Recommendations in the US 2025

Data Sources: CDC Vaccination Recommendations 2025, CDC Child and Adolescent Immunization Schedule 2025

The CDC vaccination schedule for 2025 provides comprehensive guidance for pertussis prevention across all age groups, though declining adherence to these recommendations has contributed directly to the current outbreak. The schedule begins with infants receiving three primary doses of DTaP vaccine at 2, 4, and 6 months of age, establishing foundational immunity during the most vulnerable period. Toddlers receive a critical fourth booster dose between 15-18 months, which reinforces waning immunity from the primary series. School-age children receive their fifth and final childhood dose between 4-6 years, typically before kindergarten entry.

Adolescents require a Tdap booster at 11-12 years because immunity from childhood DTaP vaccination diminishes over time. The Tdap vaccine protects approximately 70% of recipients during the first year but declines to 30-40% protection by four years post-vaccination, explaining why vaccinated adolescents and adults can still contract and transmit pertussis. All adults should receive a Tdap booster at least once and then every 10 years to maintain protection. Pregnant women represent a critical vaccination target, with CDC recommending Tdap during every pregnancy in the third trimester (between 27-36 weeks gestation). This timing allows maternal antibodies to transfer to the fetus, providing passive immunity that protects newborns during their first vulnerable months before they’re eligible for vaccination. Healthcare workers and other close contacts of infants should ensure current vaccination status. Despite these clear recommendations, 2025 has witnessed declining adherence, with kindergarten coverage falling to 92.1% and increasing numbers of pregnant women forgoing Tdap, directly contributing to the 169 infant cases and multiple preventable deaths documented throughout the year.

Factors Contributing to the Pertussis Outbreak in the US 2025

Data Sources: CDC SchoolVaxView 2024-25, CDC Pertussis Surveillance, State Health Department Reports

The 2025 pertussis outbreak results from a convergence of multiple interconnected factors that have weakened population immunity. The most significant driver is the steady erosion of childhood vaccination rates, with kindergarten DTaP coverage declining from 95% in 2019-20 to 92.1% in 2024-25. This 2.9 percentage point drop may seem modest, but it translates to tens of thousands of unprotected children and falls below the critical 95% threshold needed for community immunity. Simultaneously, vaccine exemptions have reached unprecedented levels at 3.6%, representing approximately 138,000 kindergartners attending school without complete vaccination—a 44% increase from the 2.5% rate five years earlier. Geographic clustering of these exemptions in states like Idaho, which has only 78.3% coverage and nearly 15% exemption rates, creates vulnerable communities where pertussis can spread rapidly.

Waning vaccine immunity compounds the coverage problem. Even fully vaccinated individuals lose protection over time, with Tdap effectiveness dropping from 70% in the first year to just 30-40% by four years post-vaccination. This explains why vaccinated school-age children and adolescents contribute substantially to transmission chains. The return to pre-pandemic social patterns has restored opportunities for respiratory disease transmission that were suppressed during 2020-2021 when masking, distancing, and remote schooling inadvertently reduced pertussis cases to historic lows. Children who missed routine vaccination appointments during pandemic disruptions now form cohorts with incomplete vaccine series, creating additional vulnerability. Declining maternal Tdap vaccination during pregnancy has left increasing numbers of newborns without the passive antibody protection that could prevent the severe and often fatal infections documented in 169 Washington State infants and multiple infant deaths nationwide. Finally, the extremely low case counts during 2020-2023 meant fewer people developed natural immunity from infection, leaving the population more susceptible when normal transmission patterns resumed. Enhanced surveillance may contribute to better case detection, but epidemiological analysis confirms the increase reflects genuine elevated disease transmission rather than merely improved reporting.

Pertussis Symptoms and Clinical Presentation in the US 2025

Data Sources: CDC Clinical Features and Complications, Washington State DOH Patient Information

The clinical presentation of pertussis in 2025 varies dramatically by age and vaccination status, often making diagnosis challenging. The disease progresses through three distinct stages, beginning with the catarrhal stage lasting 1-2 weeks, when symptoms resemble a common cold with runny nose, low-grade fever, and mild cough. This early stage is paradoxically the most contagious period, yet symptoms are so nonspecific that infected individuals rarely seek medical care, allowing widespread transmission before diagnosis. The paroxysmal stage follows, lasting 1-6 weeks and sometimes extending to 10 weeks, characterized by violent, uncontrollable coughing fits that force air from the lungs. These paroxysms often end with the distinctive high-pitched “whoop” sound as the person gasps for air, though this classic symptom is frequently absent in infants and vaccinated individuals. Coughing fits can trigger vomiting and complete exhaustion, significantly impacting quality of life. The convalescent stage brings gradual improvement over weeks to months, though periodic coughing episodes may persist.

Infants under one year face the most severe presentations and highest complication rates. Many infected babies never develop the characteristic cough or “whoop,” instead experiencing apnea—life-threatening pauses in breathing that can cause brain damage or death. Cyanosis (blue or purple skin coloration from oxygen deprivation) is common among hospitalized infants. Approximately one in five hospitalized infants develops pneumonia, while seizures, encephalopathy, and death occur in the most severe cases. The 1% mortality rate among infected infants makes early recognition and treatment critical. Children, adolescents, and adults typically experience the classic “whooping” cough, though vaccinated individuals often have milder, atypical presentations with persistent cough lasting weeks without the characteristic whoop. This atypical presentation in vaccinated populations contributes to delayed diagnosis and continued transmission. Complications across all ages include rib fractures from violent coughing, pneumonia, weight loss from reduced appetite, sleep disturbances, and in adults, loss of bladder control during coughing fits. The 2025 outbreak has highlighted how easily pertussis spreads when infected individuals with mild or atypical symptoms unknowingly transmit the bacteria to vulnerable populations, particularly unvaccinated infants.

Disclaimer: This research report is compiled from publicly available sources. While reasonable efforts have been made to ensure accuracy, no representation or warranty, express or implied, is given as to the completeness or reliability of the information. We accept no liability for any errors, omissions, losses, or damages of any kind arising from the use of this report.

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