Omicron BA.5 variant | COVID-19 | UC Davis Health

Omicron BA.5: What we know about this COVID-19 strain

Updated Jan. 27, 2023

The omicron subvariant of COVID-19, BA.5, became one of the dominant strains of the virus in the fall of 2022 in the U.S. At that time, it was the most easily spread strain to date and is able to evade immunity from COVID infection and vaccination.

If you've been exposed to someone with the virus or have COVID-19 symptoms and are waiting for a test or your results, stay home and isolate from others.

Learn more about when you should get tested

You can also reach out to our experts using UC Davis Health’s convenient Telehealth Express Care for urgent needs or extended-hours video visits. Express care services are open Monday – Friday, 8 a.m. to 8 p.m. and Saturday – Sunday 9 a.m. to 6 p.m.

Learn more from our experts about omicron BA.5 and how you can protect yourself

All of the variants, including omicron BA.5, cause similar COVID-19 symptoms:

  • runny nose
  • cough
  • sore throat
  • fever
  • headaches
  • muscle pain
  • fatigue

Even people who have partial immunity from a previous infection or vaccination can still have a breakthrough infection. Breakthrough infections are in people who have been vaccinated or previously had COVID. However, the majority of breakthrough infections are not causing severe illness, as compared to early in the pandemic when no one had immunity.

New research finds that with each repeat COVID infection – even asymptomatic infection – your risk for complications increases. These include:

  • stroke
  • heart attack
  • diabetes
  • digestive and kidney disorders
  • long-term cognitive impairment, including dementia

Each reinfection also carries with it the risk of long COVID or ongoing COVID symptoms that can last for weeks or months after infection.

See which COVID-19 symptoms you should watch for

At-home COVID test instructions, accuracy, and where to find one

Learn more about omicron BA.5 and how you can protect yourself

Yes, COVID-19 vaccines continue to provide good protection against the BA.5 variant. Vaccines are especially good in preventing severe disease that may cause hospitalization.

Omicron BA.5 is more likely to cause less severe illness compared to other variants. The majority of breakthrough infections (people who have been vaccinated or previously had COVID) are not resulting in severe illness. Given how infectious BA.5 is, it’s important for everyone to take all precautions, including getting vaccinated and wearing a well-fitted face mask (N95 or KN95, if possible).

New research finds that with each repeat COVID infection – even asymptomatic infection – your risk for complications increases. This includes an increased risk for:

  • stroke
  • heart attack
  • diabetes
  • digestive and kidney disorders
  • long-term cognitive impairment, including dementia

Each reinfection also carries with it the risk of long COVID or ongoing COVID symptoms that can last for weeks or months after infection.

Read more: 9 things we've learned about long COVID so far

Most people who test positive with any variant of COVID-19 typically experience some symptoms for a couple weeks. People who have long COVID-19 symptoms can experience health problems for four or more weeks after first being infected, according to the CDC.

Yes. It’s important to know if you're infected with COVID-19 for three reasons:

  1. If your illness gets worse, you’ll want to know so you can take advantage of COVID-19 treatments.
  2. You need to know whether to isolate so you can reduce your chances of infecting others, especially those who are more vulnerable to severe COVID-19.
  3. You will want to notify anyone you were recently in contact with so they can monitor their symptoms and get tested if needed.

Although it can vary, people are generally contagious between 1-3 days before omicron symptoms show.

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.

Learn more about the latest treatment recommendations

Visitor Policies

To help limit spread of COVID-19, we have policies for visits to our hospital and outpatient clinics.

UC Davis Medical Center visitor policy

Outpatient clinic policy for caregivers