Omicron-Variant-Fact-Sheet Fact Sheet: Omicron Variant

Fact Sheet: Omicron Variant

Updates as of January 21, 2022:

  • Added information on emerging studies and clarified testing recommendations. 

What do we know about the Omicron variant?

We are still learning about the Omicron variant, including how it spreads and infects individuals as well as how it responds to vaccines. Here is what we know:

  • New variants will continue to evolve as long as there are large proportions of unvaccinated people.
  • This new variant has many mutations that impact infectiousness and the ability for immune systems to protect from infection. Some of the mutations are concerning to scientists because they are very different from other variants previously detected, and some are similar.
  • Evidence is still emerging about whether the Omicron variant causes more or less severe COVID-19 illness than other variants. There are a growing number of studies that suggest that the overall proportion of cases hospitalized during COVID-19 waves associated with the Omicron variant is less than those associated with the Delta variant. This may be due to decreased virulence of the Omicron variant, greater immunity in the population, or other causes. Additionally, there are a growing number of both human and animal studies that suggest Omicron is less likely to infect the lower respiratory tract to the degree seen in previous variants such as Delta. This difference also may play a role in results showing lower severity.
  • Many treatments are still effective against Omicron. However, two treatments (bamlanivimab/etesevimab and REGEN-COV) are not effective against Omicron and are no longer recommended while Omicron is the dominant variant. Learn more about COVID-19 treatments on the CDPH COVID-19 Treatments page.  

What is California doing in response to the new Omicron variant?

The California Department of Public Health (CDPH) is taking the following steps to protect Californians against COVID-19 and the Omicron variant:

  • Monitoring for the presence of the variant in California through the California SARS-CoV-2 Whole Genome Sequencing Initiative, known as COVIDNet. This is a public-private partnership that provides California with genomic sequencing to help understand and control the spread of COVID-19. COVIDNet gives us the ability to detect variants early.
  • Partnering with the federal Centers for Disease Control and Prevention (CDC) to gather information and expertise to help the public, local public health departments and health care providers.
  • Supporting testing in a wide range of settings including schools, airports, and residential settings at high risk for COVID-19 transmission.
  • Focusing on COVID-19 vaccination and booster efforts to ensure that all Californians have access to safe, effective, and free vaccines that can prevent serious illness and death from COVID-19. It's not too late for anyone eligible to get vaccinated or boosted to protect themselves and others against COVID-19. 

What can Californians do to protect themselves from COVID-19 and the Omicron variant?

There are four specific actions that can be taken by all Californians today to protect themselves and help slow the spread of COVID-19, including the Omicron variant.

  • Get Vaccinated: All COVID-19 vaccines currently available in California are safe and effective at preventing serious illness from COVID-19. Vaccination will protect you and those you love. Californians ages 5 and older are now eligible for vaccination. Additionally, those over the age of 12 who are at least five months since their last dose of Pfizer or Moderna, (age 18 and over) or at least two months since J&J, are eligible for a booster. To get vaccinated or get a booster call (833) 422-4255 or visit the My Turn website.
  • Wear Masks: Masks prevent the spread of COVID-19, upgrade your mask and check for good fit and filtration. Follow current state and local masking recommendations and requirements. Currently, everyone must wear a mask in indoor public settings.
  • Get Tested: You should immediately get tested for COVID-19 if you are feeling any symptoms – regardless of your vaccination status. COVID-19 symptoms can feel like a common cold (including just "the sniffles"), seasonal allergies, or flu. COVID-19 testing in California is free to anyone who needs it. You can book a free test appointment, find a walk-in test clinic, or buy a self-test kit from your local drugstore. Find a testing site online or call (833) 422-4255 or 211. Learn more about COVID-19 tests.
  • Stay Home if Sick: Stay home if you are feeling sick, test, and isolate for at least 5 days if you test positive.

What is a Variant of Concern?

The WHO determines which variants are of concern based on having one or more of the following changes that could impact global public health.

  • Increase in transmissibility or detrimental change in COVID-19 epidemiology; OR
  • Increase in virulence or change in clinical disease presentation; OR
  • Decrease in effectiveness of public health and social measures or available diagnostics, vaccines, or therapeutics.

More information: Tracking SARS-CoV-2 variants (

Can current COVID-19 tests detect the Omicron variant?

Yes, current understanding is that available PCR and most antigen tests should detect this variant.

What should someone who is returning from international travel do?

The CDC recommends that all returning international travelers test within 3-5 days after arrival, self-monitor for COVID-19 symptoms, and get tested if symptoms develop. Returning international travelers who are not fully vaccinated should quarantine for 5 days, and isolate and test if COVID-19 symptoms develop.

Originally Published on November 28, 2021