Whooping Cough Resurgence Alarms Americas as PAHO Urges Urgent Vaccination Action

The Pan American Health Organization (PAHO) has issued a renewed call to countries across the Americas to urgently address critical vaccination gaps amidst a significant resurgence of pertussis, commonly known as whooping cough. Globally, cases of the highly contagious respiratory infection dramatically increased in 2024, reaching nearly six times the number reported in 2023, according to paho's latest epidemiological update released on December 9, 2025.

A similar alarming trend has been observed throughout the Americas. After recording its lowest number of cases in 2022 with 3,284, the region saw a sharp rise to 11,202 cases in 2023, escalating further to 66,184 cases in 2024, as detailed by PAHO. Between January and November 2025, ten selected countries reported continued increases compared to previous years.

This resurgence underscores critical deficiencies in immunization coverage and epidemiological surveillance across the region. PAHO noted that the decline in whooping cough vaccination coverage during the COVID-19 pandemic contributed significantly to the current situation.

Vaccination coverage for the first dose (DTP1) and third dose (DTP3) of the whooping cough vaccine fell to two-decade lows during the pandemic, reaching 87% and 81% respectively. While coverage improved slightly in 2024 to 89% and 87%, these figures remain below PAHO's recommended 95% target, with persistent disparities between and within countries.

Infants under 12 months are the most severely affected age group, accounting for 30-40% of cases in nations like Argentina, Brazil, and Colombia, paho reported. Outbreaks have also been particularly noted in indigenous communities and rural areas, where vaccination coverage is typically lower.

Dr. Daniel Salas, Executive Manager of PAHO's Special Program on Integrated Immunization, emphasized the urgency of ensuring high and consistent vaccination coverage. He stressed the importance of protecting the most vulnerable, especially children under five, to prevent further outbreaks.

• Historical Context and Pandemic Impact: Pertussis, once a major cause of childhood mortality, saw significant declines after vaccine introduction. However, the COVID-19 pandemic's mitigation measures, such as masking and social distancing, temporarily suppressed transmission, leading to historically low case numbers globally and in the Americas. The Centers for Disease Control and Prevention (CDC) noted that this lull was followed by a return to pre-pandemic patterns and a subsequent surge once restrictions eased.

• Global Scale of the Resurgence: The global increase in whooping cough cases is substantial, with 977,000 cases reported to the World Health Organization (WHO) in 2024, a 5.8-fold rise from 167,407 cases in 2023. The Western Pacific and Europe accounted for the largest shares of these cases, with 591,193 and 296,543 cases respectively, indicating a widespread international health concern.

• Factors Contributing to Vaccination Gaps: The decline in vaccination coverage is attributed to several factors, including disruptions to routine health services during the COVID-19 pandemic and increasing vaccine hesitancy. PAHO and the CDC have both highlighted that misinformation and public distrust have contributed to lower immunization rates, particularly in the Americas and the United States, leaving more children unprotected.

• Vulnerability of Infants and Maternal Vaccination: Infants, especially those under three months old, face the highest risk of severe illness, hospitalization, and death from pertussis due to their immature immune systems and inability to be fully vaccinated. WHO and PAHO recommend vaccinating pregnant women to transfer protective antibodies to newborns, offering crucial early protection.

• Emergence of Antibiotic-Resistant Strains: A concerning development is the rise of antibiotic-resistant Bordetella pertussis strains, as highlighted by PAHO in August 2025. This resistance, potentially exacerbated by inappropriate azithromycin use during the COVID-19 pandemic, complicates treatment and underscores the need for strengthened laboratory and genomic surveillance.

• PAHO's Comprehensive Recommendations: Beyond increasing vaccination rates, PAHO urges member states to strengthen epidemiological surveillance and laboratory confirmation of cases. They also recommend ensuring booster doses for pregnant women and healthcare workers, implementing respiratory isolation for suspected cases, and promoting early diagnosis and timely antibiotic treatment.

• Waning Immunity and Vaccine Development: Current pertussis vaccines, while effective in preventing severe disease, offer immunity that wanes over time, contributing to cases in older children and adults. Researchers, as noted in a December 2025 article in Medical Republic, suggest a need for new vaccines that protect against both disease and infection, and that can also reduce transmission more effectively.

• Regional Disparities and Localized Outbreaks: Vaccination coverage varies significantly, with some countries achieving high rates while others fall below targets. For example, in 2024, 21 countries in the Americas met the 95% DTP1 coverage, but four countries remained below 80%. These disparities lead to localized outbreaks, with the United States, Mexico, Brazil, and Peru reporting significant increases in cases in 2024 and 2025.