The Washington State Department of Health currently lists two variants of concern. Each of these variants are considered highly infectious and transmissible.
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.
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.
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.
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.
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%.
The Washington Department of Health finds breakthrough cases in two ways:
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.
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.
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.
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: