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,

Flu and COVID-19 case counts are high and rising in most parts of the United States, according to recent data by the Centers for Disease Control and Prevention (CDC). RSV case counts are also elevated in most states, especially in children.

If it feels like everyone around you is fighting off a cold or recovering from the flu, it may be because respiratory illnesses are running rampant in most of the United States, and cases are only increasing.

Viral sicknesses have risen in early 2025 amid the ongoing “quad-demic” in the U.S., referring to three respiratory viruses and one gastrointestinal disease, according to the Centers for Disease Control and Prevention (CDC) data.