Preventable infectious diseases are climbing worldwide amid stalled progress with immunization campaigns, shifts in vaccine acceptance, and reductions in public health funding.

In 2026, measles continues to spread in North America, including large outbreaks in South Carolina and Utah in the United States as well as Manitoba, Canada, and Jalisco, Mexico. The U.S. incidents extend the emergency that surfaced in early 2025, after an outbreak in Texas sparked the country's largest bout of measles in the United States in three decades and fueled a deadly outbreak in northern Mexico.

In the United States, even before Health and Human Services (HHS) Secretary Robert F. Kennedy Jr. assumed office, vaccine-preventable diseases had begun resurging. But the measles outbreaks flourished as Kennedy and HHS agencies—such as the U.S. Centers for Disease Control and Prevention (CDC)—attempted to tinker with the pediatric vaccine schedule. In March 2026, a federal judge stayed a series of HHS decisions aimed at restricting vaccines, including a revision to the childhood immunization schedule that reduced the number of covered diseases from 17 to 11.

In his ruling, the judge said Kennedy's appointed members of the Advisory Committee on Immunization Practices (ACIP)—a CDC advisory panel—were unqualified to make changes to vaccine policy. In response, in early April 2026, Kennedy rewrote the panel's charter to broaden the requirements for membership. As of April 22, ACIP had not reconvened, and his department has yet to appeal the judge's ruling, although Children's Health Defense—an antivaccine group aligned with the secretary—filed a motion to dismiss the stay.

Think Global Health's disease tracker allows people from all regions to follow how and where these outbreaks develop alongside global shifts in access to vaccines.

Disease Trends to Watch 

Infectious diseases were once a leading cause of death in the United States and globally before widespread access to vaccines became available. Since 1980, cases and deaths have significantly declined.

Following changes in vaccine policy and growing hesitancy, measles and pertussis, or whooping cough, are two diseases making a comeback globally.

Measles

According to March 2026 data from the WHO, the Americas leads the globe in confirmed measles cases recorded this year. As of April, Mexico's 2026 case count has already exceeded [PDF] all last year's, and it has become the most affected country in the Americas with almost 10,000 cases. Following a surge in Manitoba, Canada has added nearly 800 cases this year to its outbreak that began in October 2024. In the United States, large outbreaks in South Carolina and Utah have put the country on track to exceed its case count for 2025 if the pace continues.

Outside the Americas this spring, Bangladesh is facing a particularly severe measles outbreak

Outside the Americas this spring, Bangladesh is facing a particularly severe measles outbreak; nearly 200 children died between March and April following suspected infections with the disease. The country's confirmed caseload has increased 20-fold from 2025.

In Europe, six countries, including the United Kingdom, lost their measles elimination status in January 2026 after declines in vaccination fueled continuous transmission for more than a year, passing the World Health Organization's benchmark for a country to lose the designation. England has recorded 407 cases in 2026 as of April 13, as the country battles an outbreak in London and surrounding cities. 

Europe isn't alone; in November 2025, Canada lost its measles elimination status after three decades of maintaining it. Low vaccination rates—particularly in conservative Mennonite communities—drove continuous transmission for more than 12 months.   

Canada's designation change meant that the Americas region as a whole lost its elimination status for the third time in seven years. The Pan American Health Organization (PAHO) removed the label from Venezuela and Brazil in 2018 and 2019, respectively, although those countries regained their standing by 2024.

PAHO will review the United States and Mexico's status in November 2026.

Whooping Cough 

Whooping cough has flourished during the first few months of 2026, as Brazil, Canada, Honduras, and parts of the United States record fresh outbreaks.

Cases have also risen in the Western Pacific Region, after Guam reported its first infections since 2015, and Vanuatu witnessed seven deaths and more than 800 cases since its outbreak began in 2025.

After decades of slow growth, the number of whooping cough cases exploded

After decades of slow growth, the number of whooping cough cases exploded from 2023 to 2024, driven by large outbreaks in Europe and Asia after a drop in vaccine coverage for children during the COVID-19 pandemic.

In 2025, large outbreaks in Japan and Australia have kept case counts high. Like that of other vaccine-preventable diseases, whooping cough's resurgence has been fueled by lower vaccination rates as well as waning immunity from pertussis vaccines. 

How This Tracker Was Made 

Motivated by this global flux, Think Global Health has partnered with the International Society for Infectious Diseases (ISID) to launch a dashboard that shows how global reductions in vaccination coverage are contributing to outbreaks of vaccine-preventable diseases such as measles around the world.

Updating weekly, the map will trace outbreaks of nine diseases featured in the CDC's routine immunization schedule: hepatitis A, hepatitis B, diphtheria, measles, mumps, pertussis (whooping cough), polio, respiratory syncytial virus, and varicella (chickenpox). The Think Global Health team has selected these diseases for their severity, transmissibility, and overall ability to harm the health of people and communities.

The map's real-time data is provided by ISID's Program for Monitoring Emerging Diseases (ProMED), a long-standing program conducting global reporting of infectious disease outbreaks using global experts to review and filter reputable news and official sources. Yearly historical data from 2000 to 2024 comes from the World Health Organization's Joint Reporting Form on immunization.  

Why It Matters 

Major shifts in the global immunization funding landscape foretell an uncertain future for vaccination programs. Citing concerns around vaccine safety, the Trump administration told Gavi, a global partnership between multilateral organizations, governments, and drug manufacturers responsible for immunizing half the world's children, that it will provide funding only if the organization removes the mercury-based preservative thimerosal from its vaccines. The ingredient has a long safety record.

The announcement followed the 2025 dismantling of the U.S. Agency for International Development (USAID), once a major supporter of Gavi, along with aid cuts from other donor countries.