After the holiday season and an uptick in travel, California is seeing a rise in respiratory illnesses, prompting health experts to talk of a potential “quad-demic.” The term refers to the simultaneous spread of four major viruses: COVID-19,

The flu vaccine is generally about 40% effective at completely preventing influenza, according to Blumberg. The flu vaccine protects against three strains of influenza, including two influenza A strains. It also protects against influenza B, which typically shows up later in the season, Blumberg said.

Flu season is here in California, but other illnesses are in full swing in the Golden State. Here are the symptoms and how long you're contagious.

The CASPER also found that just less than half of households reported having at least one health symptom caused by the cross-border sewage crisis, such as headaches, nausea and dry throat. Most with chronic conditions, such as allergies, migraines, asthma and lung pain, said their symptoms have worsened.

Meanwhile, the agency urges faster testing for avian influenza A(H5N1) in hospitalized patients with suspected influenza.

The CDC has confirmed a positive bird flu case in a child in San Francisco, the second juvenile case of H5N1 in the country.

The CDC says a new strain of norovirus now makes up a majority of outbreaks and that could be why it's spreading so quickly. Stephanie Stahl reports.

The Los Angeles fires continue to cause devastation across the state as evacuation shelters have been hit with a highly contagious virus.

A new federal report shows that one drink per day is associated with negative health effects like liver cirrhosis and cancer, while a recent report from the surgeon general highlighted cancer risks associated with moderate alcohol consumption.

Moderna secured a $590 million package from the U.S. Health and Human Services Department to accelerate the development of its bird influenza vaccine as concerns about a bird flu pandemic in humans grows.

First came the fires. Then, there was ash and contaminated water. Now, some survivors of the Southern California wildfires are dealing with outbreaks of norovirus and other stomach ailments at a shelter set up to help evacuees.