What you need to know about the "kraken" subvariant


In this article: 

  • A Swedish infection control expert answers questions about the omicron subvariant currently driving COVID-19 infections. 
  • The new variant, nicknamed the kraken because of its strength, is the most transmissible subvariant yet of the virus that causes COVID-19. 
  • Vaccination, masking and proper hand hygiene are some ways we can protect ourselves and others.  
  • Swedish is working diligently to protect caregivers, patients and visitors. We are carefully monitoring the Washington State Department of Health and other agencies for new information and guidance. 

A subvariant of the omicron strain of COVID-19 is quickly spreading across the United States and is currently the dominant strain of the virus that causes COVID-19. This new subvariant—nicknamed the kraken variant—was first detected in the fall in New York State. According to the U.S. Center for Disease Control and Prevention (CDC), the kraken variant now makes up some 43% of COVID cases in the United States. Though COVID-19 transmission rates in King County remain low, a leader from the World Health Organization (WHO) characterized XBB.1.5 as “the most transmissible subvariant yet” of the virus that causes COVID-19. In December, local health leaders in King County recommended that everyone wear masks indoors.

To learn more about this variant and how to protect ourselves, we spoke with Evan Sylvester, senior director of infection prevention at Swedish, who shared some information about the variant, important protective steps we can take and what Swedish is doing to defend against this highly contagious subvariant of COVID-19.

"The kraken is not just Seattle's professional ice hockey team, it's now also the newest of many COVID-19 subvariants and the circulating dominant strain. Studies indicate that the kraken subvariant can bind more tightly to the target sites in a host allowing it to be spread easily between hosts,” says Evan. “Fortunately, the data indicates that COVID-19 has not surged this winter and is likely due to natural immunity from past infections and vaccine induced immunity. This indicates that we are likely entering an endemic state, where the virus is still circulating, but at a much lower rate that’s more manageable than past surges. While the WHO has classified it as the most transmissible subvariant, there are still things we can do to protect ourselves and others.”

What is XBB.1.5?

XBB.1.5 is a subvariant of the omicron subvariant family of COVID strains. It is actually a cross between two earlier strains of the omicron XBB subvariant: BA.2.75 and BA.2.10.1. The first XBB variant was the cause of a serious wave of infections in countries around the world. The WHO flagged it in the fall as a serious concern.

How can we protect ourselves from XBB.1.5?

  • Vaccinate. Current data still indicates that the COVID vaccines (both monovalent and bivalent) do provide some protective benefits, while not as robust against newer variants, vaccination is still important to help reduce severe disease.
  • Mask up. If you are a high-risk individual or are around others considered to be high risk (e.g., immunocompromised). Wearing a well fitted mask with multiple layers of fabric will further reduce your risk of infection. The Washington State Secretary of Health Mask Order still requires wearing a mask in health care settings.
  • Practice proper hand hygiene. Wash your hands frequently and avoid touching your eyes, nose, or mouth unless you have washed your hands.
  • Quarantine when necessary. If you do become infected with COVID-19 or another viral respiratory illness, stay home and avoid contact with others to reduce the spread of the virus. If you do need to go out in public or be around others wear a mask if possible.
  • Access available treatments. If you do get COVID, an antiviral treatment, such as Paxlovid, may be prescribed by a physician for individuals 12 years of age and older that become infected and are considered high risk. These medications must be started as soon as possible, typically within 5 days of when symptoms first appeared.

How fast is it spreading and is it more dangerous than other strains?

Fast. In late fall and early winter, the subvariant accounted for a small percentage of COVID-cases in the U.S. Now we are not very far from the 50% mark, so it’s spreading quickly. The variant is so contagious because it is a hybrid form of two previous variants that is now really good at evading the body’s defenses.

We don’t know yet a lot about the effects, but at this point the symptoms do not look any more severe than previous variants. That said, we are still seeing a large influx of cases—plus influenza and other respiratory infections—in our hospitals and emergency departments. One thing we do know is that it is important to get vaccinated, including getting flu shots and staying fully up to date with COVID boosters. In the United States, our vaccination rate is quite low compared to other industrialized countries. Those statistics influence how dangerous we understand the virus to be.

What is Providence Swedish doing to protect patients and staff from this new subvariant?   

  • Our infection prevention team continues to closely monitor the Washington State Department of Health, CDC, and WHO for new information on COVID-19 cases and guidelines from these agencies and local health departments.
  • Across Providence Swedish facilities, we are following the Washington State Secretary of Health Mask Order, which still requires all caregivers, visitors, and patients to wear a mask while in health care settings.
  • We are limiting the number of visitors allowed at a time, so please check ahead of time prior to visiting the hospital.
  • We are promoting the COVID vaccines and boosters, along with flu vaccines, for our caregivers and patients. 
  • We are requiring all caregivers to screen for COVID symptoms prior to their shift; if a caregiver is symptomatic and requires COVID-19 testing, our caregiver health department, which runs 24 hours a day, seven days a week, must be notified. 
  • Our environmental service department is routinely disinfecting high touch surfaces throughout the hospitals.

Why is it called the kraken variant?

The name has nothing to do with a sports team here in Seattle! COVID-19 variants are named by a group of WHO experts who use the Greek alphabet to name strains, alpha, beta and so on. The kraken nickname came from social media, where a professor dubbed this new strain the kraken after the mythological monster because of its unusual strength. 


Learn more and find a doctor

If you have concerns about your health or it’s time for a check-up, it’s important to see a primary care provider. Whether you require an in-person visit or want to consult a doctor virtually, you have options.
Swedish Virtual Care connects you face-to-face with a nurse practitioner who can review your symptoms, provide instruction and follow up as needed. If you need to find a doctor, you can use our provider directory.

Additional resources

Six things you should know about the new COVID boosters 

Under the weather? Tips to help you figure out if it's the flu or a cold

It's National Handwashing Awareness Week. Clean hands save lives.

ER, urgent care or your doctor's office? Know where to go and when


This information is not intended as a substitute for professional medical care. Always follow your health care professional's instructions.

Follow us on FacebookInstagram and Twitter

Previous Article
Every drop counts. January is National Blood Donor Month
Every drop counts. January is National Blood Donor Month

A Swedish expert explains the importance of blood donations and the real-life consequences for many patient...

Next Article
MLK Day 2023: Continuing the work of Dr. King's dream
MLK Day 2023: Continuing the work of Dr. King's dream

This year marks the 60th anniversary of Dr. King's monumental "I Have a Dream" speech.