Pandemic & Infectious Disease — 2026-03-25

Active Outbreak Tracker

Measles — United States

• Status: Accelerating — case count rising week over week
• Key Development: The latest CDC numbers released around March 20, 2026 show a 9.18% increase in measles cases from the prior week — an acceleration from the previous week's 6.3% rise. The compounding weekly increases signal that the outbreak has not yet peaked.
• Response: CDC continues monitoring and updating case counts; public health authorities are urging vaccination catch-up, particularly for unvaccinated children and communities with lower MMR coverage.

Tuberculosis — Global

• Status: Persistent global health emergency; projections of 4.5 million cases across 16 major markets by 2033
• Key Development: World Tuberculosis Day on March 24 prompted renewed expert focus on the disease. Researchers note that while TB is often perceived as a distant problem, cross-border movement of people and pathogens means "global health is local health." Clinical trials tracking Phase III TB vaccines and multidrug-resistant TB (MDR-TB) treatments are ongoing and closely watched this year.
• Response: Multiple Phase III trials for TB vaccines and MDR-TB treatments are currently enrolling or reporting data. GlobalData epidemiologists are projecting a continued rise in TB burden without accelerated intervention.

1 sources

clinicaltrialsarena.com

clinicaltrialsarena.com

Respiratory Viruses (COVID-19, Influenza, RSV) — United States

• Status: Winding down; CDC does not anticipate additional outlook updates for the remainder of the 2025–2026 season
• Key Development: CDC's respiratory illness data channel, updated within the past week, notes that the agency does not anticipate producing additional outlook updates during the remainder of the 2025–2026 respiratory season — an indication that flu, COVID-19, and RSV activity is subsiding toward seasonal norms.
• Response: California public health continues to recommend RSV immunization with monoclonal antibodies (nirsevimab and clesrovimab) for eligible infants and children through April 30, 2026.

Vaccine & Treatment Pipeline

• VLA15 Lyme Disease Vaccine (Pfizer / Valneva): On March 23, 2026, Pfizer and Valneva announced topline Phase 3 results from the VALOR trial, showing over 70% efficacy against Lyme disease. Despite the trial enrolling fewer Lyme cases than originally projected due to lower-than-expected incidence in the study period, both companies said they intend to seek FDA approval. Lyme disease — caused by bacteria spread by ticks — can cause arthritis, muscle weakness, and pain, and currently lacks an approved vaccine in the US.

• VAX-31 Pneumococcal Conjugate Vaccine (Vaxcyte): Vaxcyte announced on March 23, 2026 that it has completed enrollment of both the OPUS-1 and OPUS-2 Phase 3 trials evaluating VAX-31 for the prevention of invasive pneumococcal disease and pneumonia in adults. The OPUS-1 trial is designed as a head-to-head comparison against Capvaxive (PCV21) and Prevnar 20 (PCV20), the current standard-of-care vaccines, aiming to establish a new benchmark for adult pneumococcal immunization.

• TB Vaccines & MDR-TB Treatments (Multiple developers): Clinical Trials Arena reported this week that several Phase III TB vaccine candidates and MDR-TB treatment regimens are in active reporting or enrollment phases for 2026. With GlobalData epidemiologists projecting TB cases across 16 major markets to reach 4.5 million by 2033, the pipeline is under intense scrutiny from global health stakeholders.

1 sources

euronews.com

euronews.com

Expert Analysis

World Tuberculosis Day on March 24, 2026 brought renewed attention to what researchers describe as a dangerously underestimated global threat. Experts interviewed by Newswise emphasized that TB is frequently mischaracterized as a problem confined to low-income countries — a perception they say is both inaccurate and dangerous. "In a connected world, global health is local health," researchers noted, pointing out that people and pathogens routinely cross borders. The resurgence of drug-resistant TB strains further complicates the outlook, with MDR-TB requiring lengthy, costly, and often toxic treatment regimens that are out of reach for many health systems.

The Lyme disease vaccine announcement from Pfizer and Valneva also drew comment from the infectious disease community. The VALOR trial's results — over 70% efficacy despite enrolling fewer cases than expected — were characterized as "strong" by both companies and outside observers. Pfizer framed the regulatory push as an effort to "fill a major unmet medical need" and diversify its pipeline after losing several high-profile product bets in recent years. No approved Lyme disease vaccine exists in the US market, making this a potentially significant development for the approximately 476,000 Americans diagnosed annually.

On the broader pandemic preparedness front, the PBS Frontline documentary marking the sixth anniversary of COVID-19 being declared a pandemic highlighted a worrying convergence: global health funding cuts, shifting policy priorities, and the spread of health misinformation are collectively eroding the preparedness architecture built in the wake of COVID-19. Though published slightly outside the strict coverage window, the themes it raises are directly relevant to multiple active developments this week — including measles acceleration and TB's resurgence — both of which experts attribute in part to vaccination gaps that grew during and after the COVID-19 pandemic.

Global Health Security

Wellcome Infectious Disease Clinical Trial Award — Up to £8 Million Available: Announced March 23, 2026, Wellcome — in partnership with the National Institute for Health Research — is offering funding of up to £8 million through its Infectious Disease Clinical Trial Award: Optimising Interventions for Impact. The grant targets researchers working in infectious diseases globally, with an explicit focus on trials that can influence care in low- and middle-income settings. This represents a meaningful investment signal amid broader conversations about shrinking global health budgets.

CDC Respiratory Season Wind-Down — Surveillance Posture Shifts: The CDC announced this week that it does not plan to issue additional respiratory season outlook updates for the remainder of 2025–2026. While this reflects expected seasonal decline, public health experts note that the transition period — when institutional attention shifts away — historically coincides with under-detection of late-season variants or novel pathogen introductions.

Pandemic Preparedness Under Scrutiny Six Years After COVID-19: A PBS Frontline analysis published this week examined the state of pandemic preparedness at the six-year mark since COVID-19 was declared a pandemic. The report documented global health funding cuts, policy shifts at major institutions, and the erosion of international cooperation frameworks — warning that the systems intended to prevent the next pandemic are materially weaker today than in 2020.

1 sources

pbs.org

pbs.org

What to Watch Next

• Measles trajectory in the United States: With cases accelerating at over 9% week-over-week, public health officials and epidemiologists will be watching closely to see whether this trend continues or begins to flatten. The coming weeks will reveal whether current outbreak response — vaccination campaigns, school exclusion policies, contact tracing — is sufficient to bend the curve.

• Pfizer/Valneva FDA submission timeline for Lyme vaccine: Now that Phase 3 VALOR trial data has been released, the next milestone is a formal FDA regulatory submission. Analysts will monitor when the companies file, how the agency handles the efficacy question given lower-than-expected case enrollment, and whether a potential approval could arrive ahead of the 2027 tick season.

• Phase III TB vaccine readouts: With GlobalData projecting TB's continued rise and multiple trials in active data-reporting phases, any efficacy signal — positive or negative — from the TB vaccine pipeline could reshape treatment and prevention strategies for one of the world's deadliest infectious diseases. Key trials are expected to report data throughout 2026.