CDC’s Latest H5 Bird Flu Update: What We Know, What We Don’t, and Why Person-to-Person Spread Still Matters

The practical takeaway

As of early 2026, the CDC continues to confirm human cases of H5N1 bird flu in the United States — mostly in people with direct exposure to infected dairy cattle or poultry. The agency’s assessment remains the same: the risk to the general public is low. What has not been seen in the U.S. is sustained person-to-person spread. That line matters more than any single case count.

Here’s what we know, what we don’t, and why public health officials are watching this closely.

What CDC’s latest updates show

According to CDC’s H5N1 response updates from early 2025, about 70 confirmed human cases of avian influenza A(H5) were identified in the United States since April 2024. Most infections were linked to occupational exposure — especially dairy farm workers and poultry workers. In a few cases, the exposure source was unclear.

In February 2025, CDC reported that 67 of 70 confirmed cases involved people with known exposure to infected dairy cows or poultry. Three cases in 2025 included a dairy worker in Nevada, a poultry worker in Ohio, and a backyard flock owner in Wyoming. To date, CDC states that person-to-person spread has not been identified in the United States.

A CDC Morbidity and Mortality Weekly Report (MMWR) described one pediatric case in San Francisco detected through enhanced surveillance. Even in that situation, public health investigators found no evidence of onward transmission to close contacts.

What “no sustained human-to-human spread” actually means

This phrase is central to how public health officials assess risk.

Influenza viruses can occasionally infect humans after animal exposure. That has happened with H5N1 in the U.S., particularly during outbreaks in dairy cattle beginning in spring 2024.

But sustained transmission would mean something different: the virus spreading easily and repeatedly from one person to another, across multiple settings, without ongoing animal exposure.

That has not happened in the United States.

CDC and state health departments look for this in several ways:

Detailed contact tracing of confirmed cases
Testing close contacts who develop symptoms
Genomic sequencing to detect viral changes
Monitoring clusters in households, schools, or workplaces

So far, investigations have not identified chains of transmission beyond isolated cases.

Why person-to-person spread would change everything

If H5N1 developed the ability to spread efficiently between people, the public health risk would shift significantly. Human-to-human transmission is what turns a zoonotic (animal-to-human) infection into a broader community threat.

Historically, H5N1 infections outside the U.S. have sometimes caused severe illness. The CDC notes that globally, many prior cases reported to the World Health Organization have been serious. In the U.S., however, many recent infections linked to dairy cattle have been milder, often involving conjunctivitis (eye redness) or respiratory symptoms.

That pattern is reassuring — but influenza viruses change. CDC repeatedly notes that its risk assessment could change if the virus evolves.

What is happening in animals right now?

USDA continues to report detections of highly pathogenic avian influenza (HPAI) H5N1 in poultry flocks and dairy herds. Since March 2024, nearly 1,000 dairy herds across multiple states have been affected. Poultry outbreaks have involved commercial and backyard flocks.

USDA has implemented interstate testing requirements for dairy cattle and expanded biosecurity measures. In January 2026, USDA hosted additional biosecurity webinars for dairy and poultry producers to reduce spread among animals — an important step because animal outbreaks increase opportunities for human exposure.

For consumers, federal agencies maintain that pasteurized milk and properly cooked poultry and eggs remain safe. The FDA and USDA continue to monitor the food supply.

Who is at higher risk?

Based on CDC guidance, the highest risk groups are:

Dairy farm workers handling infected cattle
Poultry workers
Backyard flock owners
Veterinarians and animal health responders

People without direct contact with infected animals are not considered at increased risk at this time.

Symptoms to watch for

CDC clinical guidance notes that H5N1 symptoms can include:

Eye redness or irritation (conjunctivitis)
Cough
Sore throat
Fever
Shortness of breath

Anyone with recent exposure to infected birds or dairy cattle who develops these symptoms should contact a healthcare provider and mention the exposure. Early antiviral treatment may be recommended.

People without animal exposure do not need special testing.

What remains uncertain

Several important questions are still being studied:

Why some infections are mild while others globally have been severe
How the virus is adapting within dairy cattle
Whether genetic changes could increase human transmissibility
How long animal outbreaks will persist

Enhanced surveillance — including genomic sequencing and expanded influenza subtyping — is designed to detect changes early.

Why this matters for everyday Americans

For most people, there is no need to change daily routines. Schools, workplaces, and community settings are not seeing spread.

However, the situation highlights how public health surveillance works. The reason officials emphasize “no sustained person-to-person spread” is because that is the key threshold between an occupational outbreak and a broader public health emergency.

Influenza viruses evolve. Public health agencies are monitoring for warning signs so that if risk increases, guidance can change quickly.

What this means for you right now

If you do not work with infected animals, your current risk remains low.
If you do work with poultry or dairy cattle, follow CDC and USDA protective guidance closely.
Continue standard food safety practices: avoid raw milk and cook poultry and eggs thoroughly.
Seek medical care if you have animal exposure and develop symptoms.

The absence of sustained person-to-person transmission is not just a technical detail. It is the line that keeps H5N1 from becoming something much larger. For now, that line still holds — and public health agencies are working to keep it that way.

Sources

This article is for general informational purposes only and is not medical advice. Research findings can be early, limited, or subject to change as new evidence emerges. For personal guidance, diagnosis, or treatment, consult a licensed clinician. For current outbreak or public health guidance, follow your local health department, the CDC, or another relevant public health authority.