Respiratory Viruses Hub

Respiratory viruses are very active in the fall and winter. The viruses that can sometimes cause more serious illness are influenza (flu), respiratory syncytial virus (RSV) and SARS-CoV-2 (which causes COVID-19). These viruses spread quickly. When infected, most people will have a mild illness. But some people become seriously ill and can die. Learn more about the spread in your community and steps you can take to protect yourself.

Key Highlights

Seasonal influenza activity is elevated in California. This is due to the new flu strain H3N2, subclade K. Children have a higher positivity rate than adults. Hospital admission rates and emergency department visits are going up. CDPH urges vaccination, testing, and quick treatment to avoid serious illness.
RSV activity is elevated in California. More children and older adults are being hospitalized. CDPH recommends immunizations for everyone who can get them.
COVID-19 activity remains very low statewide. CDPH recommends COVID-19 vaccination, especially for people at higher risk (PDF).
Respiratory virus vaccines are available in California. Talk to your doctor or visit MyTurn to schedule your appointment.

Updated 01/16/2026

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Respiratory Virus Basics

Flu

RSV

COVID-19

Even healthy people can become very sick from a respiratory virus. Respiratory viruses like flu, RSV, and COVID-19 usually cause mild illnesses. They can cause severe complications in some people. Anyone at higher risk for serious illness should get medical help as soon as they start feeling sick.

Symptoms: Respiratory viruses affect your lungs and airways, making it hard to breathe. They can cause symptoms like coughing, body aches, and fever.
Prevention: There are vaccines available for the flu, RSV, and COVID-19. Stay up to date for the best protection.
Protection: To stay healthy, be sure to wash your hands a lot. Wear a mask in crowded spaces. Stay home and rest if you are sick.
Treatment: Get tested quickly if you have symptoms. Start treatment early to prevent serious illness.