The CDC is calling for expanded testing of bird flu after a child in California tested positive for the virus despite no known contact with animals.

Due to ongoing sporadic H5N1 avian flu infections and brisk levels of seasonal flu activity, the US Centers for Disease Control and Prevention (CDC) today urged healthcare providers to subtype all influenza A specimens in hospitalized patients, especially those in the intensive care unit (ICU), as soon as possible.

Seasonal influenza vaccines triggered protective immune responses against the H5N1 avian influenza virus primarily in younger people, indicating its potential use as a first line of defense during an eventful pandemic.

People hospitalized for flu should be tested for bird flu within 24 hours, the U.S. Centers for Disease Control and Prevention said on Thursday, in an expansion of the agency's efforts to tackle increasing infections in humans.

NBC News Medical Contributor Dr. Kavita Patel speaks with Gadi Schwartz about the difference in symptoms between a cold and the flu and explains the CDC's urge for faster testing to find human bird flu cases.

CDC officials say they extended the guidance now because they are seeing more H5N1 patients whose illness they cannot track back to an infected bird or cow.

Spartanburg has a confirmed case of the bird flu. The CDC reports the virus was detected on Dec. 31, 2024, in a flock of about 490 birds.