0
0
163 confirmed cases and 5 deaths reported in first 21 weeks of 2026 — Haiti accounts for nearly all infections
Washington, D.C. — The Pan American Health Organization (PAHO) issued an urgent call on June 15, 2026, urging countries across the Americas to strengthen routine immunization programs and close vaccination gaps following a dramatic rise in diphtheria cases throughout the region. The epidemiological alert reveals that 163 confirmed diphtheria cases, including five deaths, were reported in the first 21 weeks of 2026 — more than double the number from 2025 and significantly above recent years’ averages.
Key Findings: An Alarming Trend Resurfaces
The cases were reported in three countries: Brazil, Haiti, and Peru. Haiti accounted for the vast majority of infections with 159 cases and all five deaths recorded. More than half of confirmed cases this year occurred among people who were unvaccinated or had unknown vaccination status, highlighting the critical role of immunization in preventing this serious bacterial infection.
This surge represents a troubling reversal of decades of progress. From 2012 to 2021, the Americas witnessed a median of only 57 confirmed diphtheria cases reported annually across ten nations, with annual figures typically fluctuating between 2 and 894 cases. The peak years previously occurred in 2017 and 2018, with 872 and 894 cases respectively, but the region had made significant progress controlling the disease since then.
Vaccination Coverage Falls Below Critical Threshold
The resurgence comes as diphtheria vaccination coverage remains below levels needed to prevent outbreaks. In 2024, regional coverage for the third dose of the diphtheria, tetanus, and pertussis (DTP3) vaccine declined to 87%, well below the 95% target recommended by WHO to provide community protection.
Several countries continue reporting coverage levels below 80%, while others experience high dropout rates between the first and third vaccine doses. The COVID-19 pandemic significantly exacerbated this decline. In 2020, vaccination rates against diphtheria, tetanus, and pertussis dropped by 18.2% compared to 2019, with 474,395 fewer children in the WHO Region of the Americas receiving all three DTP3 shots. Central America saw the most important drop at -7%, with the absolute decrease in vaccine coverage across the Americas reaching -4% between 2019 and 2022.
Understanding Diphtheria: A Serious, Preventable Disease
Diphtheria is a serious bacterial infection caused by Corynebacterium diphtheriae and transmitted through respiratory droplets. The disease is characterized by the formation of a thick gray membrane (pseudomembrane) in the throat and tonsils, which can obstruct the airway.
Most people with diphtheria experience respiratory tract infection, sore throat, and mild fever in the first few days. Mild cases may not develop further symptoms, but severe cases can develop a swollen “bull’s neck” appearance from inflamed neck tissues and enlarged lymph nodes. If left untreated, toxins produced by the bacteria can lead to severe breathing difficulties, as well as damage to the heart and nervous system, and can be fatal.
Complications can include myocarditis (heart inflammation), peripheral neuropathy (nerve damage), kidney problems, and bleeding issues due to low platelet levels. Even with appropriate treatment, the case-fatality rate ranges from 5% to 10%, highlighting the need for early case management and immunization. Unvaccinated or under-vaccinated individuals remain at highest risk of infection.
Expert Commentary: Closing Gaps Is Critical
“While the Americas have made significant progress in controlling diphtheria over recent decades, the disease continues to circulate globally and can re-emerge when vaccination coverage falls,” PAHO noted in its alert.
The organization emphasizes that “it is urgent to increase coverage of both the primary series (3 doses) and the recommended boosters (3 doses) among children, adolescents, and adults” to prevent new cases and outbreaks. WHO recommends a 3-dose primary vaccination series with diphtheria-containing vaccine followed by 3 booster doses, beginning as early as 6 weeks of age.
CDC recommends vaccination every 10 years for all adults to maintain protection against diphtheria, with routine DTaP vaccination for all infants and children younger than 7 years old. Adolescents should receive a single dose of Tdap at 11 to 12 years of age.
PAHO’s Action Plan: Multi-Pronged Approach
PAHO urges countries to implement several critical strategies:
-
Microplanning strategies: Identify and vaccinate populations that have been missed. The organization recommends taking advantage of every contact with the health system to verify vaccination status and complete immunization schedules.
-
Strengthened epidemiological surveillance: Maintain close monitoring of vaccine-preventable diseases. Countries must ensure rapid laboratory confirmation of suspected cases.
-
Antitoxin supply management: Maintain steady supplies of diphtheria antitoxin for controlling potential outbreaks. The global shortage of diphtheria antitoxin (DAT) poses significant challenges for effective case management, as seen in ongoing outbreaks in other regions.
-
Workforce training: Keep health workers well-trained in outbreak detection and response. PAHO also advises countries to strengthen public awareness of diphtheria symptoms and the importance of vaccination.
Public Health Implications: What This Means for Readers
The diphtheria surge carries important implications for health-conscious individuals across the Americas:
-
Verify vaccination status: Adults should check if they’ve received their Tdap booster within the past 10 years, especially before traveling to areas with known outbreaks.
-
Children’s immunization: Ensure children receive the complete 5-dose DTaP series at 2 months, 4 months, 6 months, 15–18 months, and 4–6 years.
-
Adolescent boosters: Teenagers should receive Tdap at 11–12 years of age.
-
Symptom awareness: Recognize early signs — sore throat, mild fever, and the characteristic gray membrane in the throat — and seek medical attention promptly.
-
High-risk populations: Unvaccinated individuals, those with unknown vaccination status, and people in areas with low coverage remain most vulnerable.
Limitations and Counterarguments
While PAHO’s data is clear, some considerations warrant attention. The case distribution shows significant geographic concentration, with Haiti accounting for 98% of cases (159 of 163) and all deaths. This suggests the outbreak may be more localized than regional, though the underlying vaccination coverage problem affects the entire Americas.
The data covers only the first 21 weeks of 2026, so full-year totals remain unknown. Additionally, diphtheria reporting can be affected by surveillance capacity variations between countries, particularly in regions with ongoing social, political, and economic challenges like Haiti, where active transmission has continued since December 2014 and the disease is now deemed endemic.
Some experts note that while vaccination coverage remains suboptimal, other factors may contribute to outbreaks, including population mobility, crowded living conditions, and health system vulnerabilities — particularly in fragile or conflict-affected settings.
The Bottom Line
“Vaccination is key to preventing cases and outbreaks,” PAHO states firmly in the alert, emphasizing that closing vaccination gaps and sustaining high coverage levels remain essential to protecting populations across the Americas. The organization recommends achieving and maintaining vaccination coverage of at least 95% with the primary three-dose DTP series and recommended booster doses.
As the Americas confront this resurgent threat, the message from public health authorities is clear: diphtheria is preventable, but it requires sustained immunization efforts and vigilance against the vaccination gaps that have left pockets of the population vulnerable.
Medical Disclaimer: This article is for informational purposes only and should not be considered medical advice. Always consult with qualified healthcare professionals before making any health-related decisions or changes to your treatment plan. The information presented here is based on current research and expert opinions, which may evolve as new evidence emerges.
References
Study and Alert Sources
-
Pan American Health Organization (PAHO). “PAHO urges countries to strengthen vaccination efforts as diphtheria cases rise in the Americas.” PAHO News, June 15, 2026. https://www.paho.org/en/news/15-6-2026-paho-urges-countries-strengthen-vaccination-efforts-diphtheria-cases-rise-americas
