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Increase in breakthrough cases related to current COVID-19 surge

OLYMPIA --The Washington State Department of Health (DOH) is seeing an increase in the number of “vaccine breakthrough” cases related to the recent increase in overall cases statewide. Even with the increase in breakthrough infections, data continue to show that vaccination is highly protective against hospitalization and death from COVID-19.

Current reporting shows a recent 43% increase in the number of breakthrough cases. The increase in the number of breakthrough cases is related to the increase in the number of total cases statewide. From January 17, 2021 - January 1, 2022, there have been 123,365 vaccine breakthrough cases identified in Washington State. While the majority of individuals with confirmed vaccine breakthrough experienced only mild or no symptoms, at least 3% were hospitalized.

To date, more than 4.8 million people in Washington state are up to date on their vaccines. The breakthrough cases represent a small portion, about 2.5% of the vaccinated population.

“If you are already vaccinated, getting a booster dose of vaccine is the best way to decrease your chance of getting a breakthrough infection,” said Tao Sheng Kwan-Gett, MD, MPH, Chief Science Officer. “Even without a booster dose, those who are vaccinated are less likely to become very ill and need hospitalization, and a booster dose decreases the risk even more.”

Large-scale clinical studies have found that COVID-19 vaccines prevented most people from serious illness and hospitalization. This means a very small number of fully vaccinated people will still become infected with COVID-19. Scientists note that breakthroughs are expected with any vaccine.

A person is considered to have vaccine breakthrough if they test positive for COVID-19 using a PCR test or antigen test and received their final dose of the COVID-19 vaccine more than two weeks prior to the positive test. Additional investigations help us better understand clinical and outbreak information when vaccine breakthrough happens.

“Even though the Omicron variant has an increased ability to evade immunity from vaccination, vaccines and boosters will lower the risk that an infection could land you in the hospital,” said Dr. Kwan-Gett. “That’s why to avoid worsening the strain on our hospitals, everyone should use a high quality well-fitting mask, don’t use the emergency department unless it’s a true emergency, and most important get vaccinated and boosted as soon as you are eligible.”

Information regarding variants and breakthrough cases can be found in the SARS-CoV-2 Sequencing and Variants in Washington State. This report and the SARS-CoV-2 Vaccine Breakthrough Surveillance and Case Information Resource are located on the COVID-19 Data Dashboard :: Washington State Department of Health and are updated every week.

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