COVID-19 variants FAQ for members


Which COVID-19 variants are present in Washington state?

The Washington State Depart­ment of Health currently lists two variants of concern. Each of these variants are consid­ered highly infec­tious and transmissible.

  • Delta (B.1.617.2) The Delta variant is the predominant variant in Washington state, sequenced in over 99% of cases. While further U.S. studies are needed, some antibody treatments may be less effective against the Delta variant, and vaccine effectiveness may be lower.
  • Omicron (B.1.1.529) variant was first identified in the United States on December 1, 2021, in California, and was identified in Washington shortly after. Studies are ongoing to determine the effectiveness of vaccines and therapeutic treatments, such as monoclonal antibodies and oral antivirals, against Omicron. Due to the small number of cases, the severity of illness and death associated with this variant is unclear at this time, but more will be known in the near future. The recent emergence of the Omicron variant further emphasizes the importance of vaccination and boosters.

Additionally, monitoring of other identified variants is ongoing. These include Alpha, Beta, Gamma, Eta, Iota, Epsilon, Kappa, Mu, and Zeta. Together, these variants represent less than 1% of cases in Washington.



How does the Washington State Department of Health determine which variants are currently circulating?

The Department of Health uses genome sequencing to determine how a virus is changing over time. A sample of positive COVID-19 PCR tests are used. Washington state is currently sequencing at least 10% of positive COVID-19 tests, equating to tens of thousands of tests since January 2020.



Is there one variant that is more prevalent than others?

The Delta variant is the predom­i­nant variant in Washington state, as well as the United States. Data shows that those infected with the Delta variant have a higher viral load than those infected with other variants and is twice as conta­gious as other variants. Data also shows that unvac­ci­nated individ­uals who test positive with the Delta variant have more severe illness than older variants.



What criteria are used to determine a ‘vaccine breakthrough’ case?

The criteria for identifying vaccine breakthrough cases include a positive PCR or antigen lab test at least 14 days after a person received their last recommended dose of an authorized COVID-19 vaccine. It takes approximately two weeks after the final dose of vaccine has been administered for the body to build a high level of protection against the virus. Infections that occur within the first fourteen days after any dose in an FDA-approved vaccine regimen is not considered a breakthrough case as that person is not considered fully vaccinated. Less than 1% of COVID-19 cases in Washington are in fully vaccinated people.



Are COVID-19 vaccines effective?

All FDA-approved vaccines have shown effec­tive­ness against all monitored variants and variants of concern, and over 162 million Ameri­cans have been fully vacci­nated against COVID-19. COVID-19 vaccines have been proven effec­tive in reducing the incidence of severe illness, hospi­tal­iza­tion, and death. Over 99% of current COVID-19 hospi­tal­iza­tions and deaths are unvac­ci­nated individ­uals. Since the first COVID-19 vaccine was made avail­able, deaths due to COVID-19 in the United States have dropped by 70%.



How does the Washington State Department of Health determine vaccine breakthrough cases?

The Washington Department of Health finds breakthrough cases in two ways:

  • A DOH investigator may conduct interviews with individuals who have tested positive for COVID-19 to assess whether they have also been vaccinated.
  • Cross-checking positive COVID-19 results with Washington state’s immunization registry.



Are vaccine breakthrough cases more common in one variant than another?

DOH reports that vaccine breakthrough cases are being prioritized for whole genome sequencing so that the distribution of variants detected among breakthrough cases can be continually monitored. Currently, the Delta and Alpha variants have the highest rate of vaccine breakthrough. However, all breakthrough cases in Washington state make up less than 1% of total confirmed COVID-19 cases.



Are vaccine breakthrough cases more common in one brand of vaccine than another?

DOH reports that vaccine breakthrough has been associated with all three current authorized vaccines. It is misleading to look at breakthrough cases by vaccine brand as the number of administered doses varies by brand. Other variables include differences in dosing schedules. These factors make it difficult to directly compare numbers of breakthrough cases among vaccine brands.



Is the vaccine recommended for those who have been previously infected with COVID-19?

The Advisory Committee on Immunization Practices (ACIP) recommends anyone who previously has had COVID-19 to get the vaccine. Data shows it is uncommon to be re-infected with COVID-19 in the 90 days after infection, so there may be some natural immunity. However, it is unknown how long natural immunity might last. People who currently have COVID-19 should wait to get vaccinated until symptoms resolve, and their isolation period is finished. People who were recently exposed to COVID-19 should also wait to get the vaccine until after their quarantine period as long as they can safely quarantine away from other people. If there is a high risk they could infect others, they may be vaccinated during their quarantine period to prevent spreading the disease.



What resources are available regarding COVID-19 variants and breakthrough cases in Washington State?

The Washington State Department of Health produces weekly reports on both COVID-19 variants and vaccine breakthrough cases. These reports are published online and are updated on Wednesdays. Additional information can also be found from the following resources: