COVID-19 variants
Updated: Jan. 26, 2023
Throughout the past several years of COVID-19, the virus has mutated into different strains, including delta and omicron. Our infectious disease experts provide up-to-date information on the COVID variants, including symptoms and how effective the vaccines are at protecting you and your family.
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XBB.1.5 variant
Learn more about the XBB.1.5 variantIn December 2022, a new variant called XBB.1.5 emerged and quickly grew as the dominant strain into January 2023. This COVID mutation, also known as the "Kraken" variant, is causing similar COVID symptoms in 2023 as other recent strains.
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Omicron variant
Learn more about the omicron variantThe omicron subvariant of COVID-19, called BA.5, became one of the dominant strains of the virus in the U.S. in the fall of 2022. During that time, it was the most easily spread strain to date and was able to evade immunity from past COVID infection and vaccination.
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Delta variant
Learn more about the delta variantThe delta variant began spreading rapidly in the U.S. in June 2021. It was causing similar COVID symptoms, but physicians were seeing people get sicker quicker, especially younger people.
Latest on COVID-19 from UC Davis Health
When to contact your provider
If you have serious symptoms of illness, contact your primary care provider. UC Davis Health patients can use the MyUCDavisHealth symptom tracker to evaluate whether to seek help. Telehealth video visits and Express Care are also available.
If you have a medical emergency, call 911 and notify them of your COVID-19 symptoms.
Ways to seek treatment
If you test positive for COVID-19 at home, you can contact your primary care provider about a prescription for Paxlovid.
Patients who receive primary care or specialty care from UC Davis Health can schedule a telehealth video visit with Express Care.
Visitor Policies
To help limit spread of COVID-19, we have policies for visits to our hospital and outpatient clinics.