The Centers for Disease Control and Prevention called it the first severe case in the U.S., though the risk to most of the public is still low.

The first severe H5N1 bird flu case in the US raises alarm as experts discuss symptoms, risks, and vaccine development for humans and animals.

The current US outbreak of the flu – technically the Highly Pathogenic Avian Influenza, or H5N1 bird flu – was first reported in March in dairy cows. US cases have included a young child in California, reported in November. Authorities subsequently screened other children and caregivers at the child’s daycare as a precautionary measure.

This marks the first case of H5N1 bird flu in the US connected to backyard flock exposure, according to health officials.

The H5N1 strains are becoming more concerning as the first severe U.S. case has been detected and California declared a state of emergency.

At least 61 people in the US have contracted bird flu amid outbreaks in poultry and dairy cows. What are the symptoms? What to know about highly pathogenic avian influenza, aka, H5N1.