Pandemic & Infectious Disease — 2026-03-31

Active Outbreak Tracker

Respiratory Virus Season — United States

• Status: Low activity nationally; CDC indicates it does not anticipate additional outlook updates for the remainder of the 2025–2026 respiratory season
• Key Development: CDC's Respiratory Illnesses Data Channel, updated within the past few days, confirms that COVID-19, flu, and RSV activity has wound down significantly across the U.S. The agency stated it will continue monitoring but does not expect to issue further seasonal outlook updates, suggesting the worst of the 2025–2026 respiratory season has passed.
• Response: CDC continues routine surveillance via its Respiratory Virus Activity Levels tracker and Rt-estimation tools for COVID-19, influenza, and RSV at the state level.

5 sources

cdc.gov

cdc.gov

cdc.gov

Respiratory Illnesses Data Channel | Respiratory Illnesses | CDC

cdc.gov

Measles Cases and Outbreaks | Measles (Rubeola) | CDC

cdc.gov

cdc.gov

cdc.gov

Global Measles Outbreaks | Global Measles Vaccination | CDC

Mpox (Monkeypox) — Global

• Status: Ongoing; outbreaks of both clade I and clade II mpox are occurring in multiple countries
• Key Development: CDC's situation summary page, updated within the past week, confirms that clade I and clade II mpox outbreaks continue to be monitored globally. The dual-clade situation remains an active public health concern, particularly given clade I's higher historical severity profile.
• Response: CDC and WHO continue coordinating global surveillance and response efforts. Vaccination campaigns using available orthopoxvirus vaccines are ongoing in affected regions.

5 sources

cdc.gov

cdc.gov

cdc.gov

Respiratory Illnesses Data Channel | Respiratory Illnesses | CDC

cdc.gov

Measles Cases and Outbreaks | Measles (Rubeola) | CDC

cdc.gov

cdc.gov

cdc.gov

Global Measles Outbreaks | Global Measles Vaccination | CDC

COVID-19 Variant Surveillance — Global

• Status: Active monitoring; WHO TAG-CO-VAC convening ahead of May 2026 composition meeting
• Key Development: On March 30, 2026, WHO published a formal notice detailing the types of data being requested to inform the May 2026 COVID-19 vaccine antigen composition deliberations. The TAG-CO-VAC committee is closely monitoring the genetic and antigenic evolution of circulating SARS-CoV-2 variants, immune responses to infection and vaccination, and the real-world performance of current vaccines against circulating strains.
• Response: WHO's Technical Advisory Group on COVID-19 Vaccine Composition (TAG-CO-VAC) is soliciting submissions from researchers and manufacturers ahead of its scheduled May 2026 meeting, which will determine recommendations for updated vaccine formulations.

Vaccine & Treatment Pipeline

• Anktiva (N-803) for Long COVID (ImmunityBio): Entered Phase 2 clinical trial as of late March 2026. Founder Patrick Soon-Shiong disclosed he was invited by a European health minister to discuss expanding "immunotherapy 2.0," signaling potential transatlantic expansion for the IL-15 superagonist platform that already holds FDA approval in bladder cancer.

• Federal Vaccine Recommendations Freeze (U.S. HHS/CDC): As of March 16, 2026, all changes to federal vaccine recommendations made between June 2025 and March 2026 have been placed on hold. The Public Health Communications Collaborative, which updated its guidance 2 days ago, is advising public health professionals to be aware of this freeze and its downstream effects on clinical and public communication.

• COVID-19 Vaccine Antigen Composition 2026 (WHO/Global Manufacturers): WHO TAG-CO-VAC issued its formal data call on March 30, 2026, ahead of the May 2026 meeting where next-generation COVID-19 vaccine strain selections will be finalized. This process mirrors the annual influenza strain selection mechanism and will shape the composition of updated COVID vaccines rolled out later in the year.

Expert Analysis

A commentary published in The Lancet approximately five days ago — placing its publication date around March 26, 2026 — calls on world leaders to elevate "spillover prevention" as a central pillar of the upcoming UN High-Level Meeting on pandemic prevention, preparedness, and response (PPPR). The authors argue that while COVID-19 briefly thrust pandemic preparedness to the forefront of the global political agenda, sustained attention has waned in the face of competing crises including inflation and armed conflict. The piece urges that the 2026 PPPR meeting represent a turning point, not merely a rhetorical exercise.

Separately, Lancet Infectious Diseases editorial priorities for 2026 — as summarized in third-party journal-tracking resources — place pandemic preparedness, emerging pathogens, antimicrobial resistance, and vaccine effectiveness studies at the top of the field's research agenda. This reflects a growing consensus in the infectious disease community that structural investments in detection and response infrastructure must accelerate before the next major pathogen emerges, not after.

The freeze on U.S. federal vaccine recommendations, noted by the Public Health Communications Collaborative this week, has added a layer of domestic uncertainty to an already complex global landscape. Public health professionals are being advised to communicate carefully with patients about which guidance remains in effect — a challenge that epidemiologists warn could erode institutional trust at a moment when public confidence in vaccines remains fragile.

Global Health Security

WHO COVID-19 Vaccine Composition Process — May 2026 Deliberations: On March 30, 2026, WHO formally launched its data solicitation process ahead of the TAG-CO-VAC May 2026 meeting. This biannual process determines which SARS-CoV-2 variant antigens should be included in updated COVID-19 vaccines. The outcome will directly influence which formulations manufacturers produce for the next immunization cycle, making it one of the most consequential near-term decisions in global health governance.

UN High-Level Meeting on PPPR — Lancet Advocacy: A Lancet commentary published around March 26, 2026, urges governments to use the upcoming UN High-Level Meeting on pandemic prevention, preparedness, and response as a genuine policy milestone. The authors specifically highlight spillover prevention — the process by which pathogens cross from animal reservoirs to humans — as an underfunded and underemphasized component of global health security frameworks.

U.S. Federal Vaccine Recommendation Freeze: Updated guidance from the Public Health Communications Collaborative (updated March 29, 2026) confirms that a freeze on all federal vaccine recommendation changes made between June 2025 and March 2026 took effect on March 16. Public health agencies and clinicians are navigating a period of policy uncertainty that could affect immunization schedules across multiple vaccine-preventable diseases.

What to Watch Next

• WHO TAG-CO-VAC May 2026 Composition Meeting: The outcome of WHO's antigen composition deliberations will determine the formulations of the next generation of COVID-19 vaccines. Data submissions are now open following the March 30 call, and the May meeting result will set the clock ticking for manufacturers. Watch for which circulating variants are designated as priority antigens and whether booster recommendations shift accordingly.

• U.S. Vaccine Policy Uncertainty: With federal vaccine recommendation changes frozen since March 16, healthcare providers are operating without updated federal guidance across multiple disease areas. Monitor whether Congress acts on related legislation or whether HHS issues clarifying guidance — and watch for public health data signals that could indicate downstream impacts on vaccination rates.

• Mpox Dual-Clade Global Situation: With both clade I and clade II mpox outbreaks continuing across multiple countries, the distinction in severity and transmission dynamics between the two clades remains a critical surveillance target. Any geographic expansion of clade I — historically associated with higher case fatality rates — would warrant heightened international response.