Whooping Cough Surges Across the US, Driven by Declining Vaccination Rates
A nationwide outbreak of pertussis, commonly known as whooping cough, is rapidly escalating, with cases surging in states like Texas, Florida, California, and Oregon. The resurgence is attributed to falling vaccination rates, waning immunity, and challenges in public health tracking, posing a significant risk, particularly to infants too young to be fully vaccinated.
A Growing Public Health Threat
Pertussis cases historically fluctuate in cycles due to waning immunity, but experts warn the current outbreak’s scale and potential severity are concerning. “Pertussis cases increase in a cyclical fashion driven by waning immunity, but the size of the outbreak and the potential for severe outcomes in children who cannot be vaccinated can be mitigated by high coverage and good communication to folks at risk,” stated a former head of the Centers for Disease Control and Prevention (CDC) immunization program.
Before the introduction of the first pertussis vaccine in the early 1900s, whooping cough was a leading cause of childhood illness and death in the United States. Today, children receive a series of DTaP vaccinations beginning at 2 months old, with adolescents and adults receiving a Tdap booster every 10 years to protect against diphtheria, tetanus, and pertussis.
Vaccination Coverage Declines
For years, approximately 8 in 10 toddlers had received four doses of the DTaP vaccine by age 2, effectively controlling case rates. However, vaccination coverage has steadily declined since the onset of the COVID-19 pandemic, and increasing nonmedical exemptions in several states have further widened immunity gaps – the point at which a sufficient proportion of the population is no longer immune to prevent widespread transmission.
The numbers paint a stark picture. Texas recorded 1,928 pertussis cases in 2024, exceeding 3,500 by October 2025. Nationally, the US tallied 6,600 cases in the first three months of 2025 – four times the rate observed last year and 25 times the number reported in 2023. Multiple states are experiencing their highest case totals in a decade, indicating the outbreak is not isolated but widespread.
Policy Changes and Barriers to Access
Recent policy changes in some states are exacerbating the problem. In Texas, a new law now allows parents to more easily claim nonmedical exemptions from school vaccine requirements by downloading forms online directly from schools, bypassing health departments and hindering tracking efforts.
Phil Huang, Director of Dallas County Health and Human Services, anticipates this new rule will further decrease school-level vaccination rates, though the full impact remains to be seen. He has already observed a significant drop in vaccinations, noting that the usual crowds during back-to-school season were absent this year.
Huang also believes that fear of immigration enforcement may be deterring some families, particularly Hispanic families who comprise approximately 40% of Dallas County’s population, from seeking vaccination. “We think that a lot of them are deterred by the ICE activity,” he said, referring to Immigration and Customs Enforcement.
Waning Immunity and Evolving Vaccines
The effectiveness of pertussis vaccines, while protecting against severe disease, diminishes over time, similar to the patterns observed with COVID-19 and influenza vaccines. The US transitioned from whole-cell pertussis vaccines to “acellular” vaccines in the 1990s, which cause fewer side effects but offer shorter-lasting immunity. Consequently, a larger proportion of adults today received the acellular vaccine as children and may have lost immunity, unknowingly transmitting the infection to vulnerable infants.
Infants at Greatest Risk
Whooping cough poses the most significant threat to infants under one year old. The infection can cause severe coughing fits leading to breathing difficulties, pneumonia in approximately 1 in 5 cases, and, tragically, death in about 1% of infants.
To mitigate this risk, the CDC strongly recommends that pregnant women receive a Tdap vaccine during each pregnancy, allowing protective antibodies to pass to the baby before birth. While “cocooning” – vaccinating all close contacts of the infant – was previously promoted, it proved difficult to implement consistently and is no longer widely recommended. Vaccination of pregnant women and infants at 2 months of age remain the most effective protective strategies.
Improved Detection and Emerging Resistance
Increased use of modern PCR testing is also contributing to the higher number of reported cases. Clinics now routinely use this technology to test for multiple respiratory infections simultaneously, including pertussis, a practice that was less common a decade ago. While improved testing explains some of the increase, experts emphasize that the substantial rise in infant hospitalizations and the widespread nature of outbreaks confirm a genuine increase in transmission.
A growing concern is the emergence of antibiotic resistance. While macrolide antibiotics – such as erythromycin, azithromycin, and clarithromycin – are typically used to treat pertussis, resistance is becoming increasingly common abroad, particularly in China and Peru. Although resistant cases remain rare in the US, CDC officials warn that international travel could facilitate the spread of these strains, potentially limiting treatment options, especially for infants.
Looking Ahead: A Multifaceted Response
The resurgence of whooping cough is not attributable to a single factor but rather a confluence of challenges: declining vaccine coverage, low rates of Tdap vaccination among pregnant women (currently around 60%), waning immunity, improved testing capabilities, and early signs of antibiotic resistance.
Health experts emphasize that addressing this complex problem requires a multifaceted approach. Clinicians are being urged to consider pertussis in patients presenting with persistent coughs, particularly children and caregivers of newborns. Immediate medical attention is crucial for infants experiencing breathing difficulties or turning blue. Obstetricians are encouraged to discuss Tdap vaccination during every pregnancy, and pediatricians and family doctors should verify booster status for adolescents and adults.
Several states, including Texas, have issued health advisories urging clinicians to remain vigilant. Public health outreach programs, however, are struggling to rebuild after funding cuts during the COVID-19 pandemic, leading to staffing limitations. Furthermore, delayed immunization registry data – now received monthly instead of daily in some counties like Dallas – hinders real-time tracking of vaccination coverage.
As the holiday season approaches, experts urge families with newborns to prioritize vaccination against influenza, COVID-19, and RSV, in addition to pertussis, and to limit exposure to sick individuals. Prompt medical attention is vital if an infant develops a cough or experiences pauses in breathing.
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