COVID-19 vaccine breakthrough cases have increased in Washington state, the Department of Health says, but vaccines continue to provide protection.
Breakthrough cases recently increased 43%, according to a Thursday news release. The state counts a breakthrough case if a person tests positive for COVID-19 via a PCR or antigen test and has received their final vaccine dose over two weeks prior.
The state believes the increase is related to the record-breaking surge in disease activity across the state.
The more transmissible Omicron virus variant has come to dominate the recent wave in infections after first being detected in early December. Since then, cases have skyrocketed and local hospitals have been strained.
"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," DOH Chief Health Officer Tao Sheng Kwan-Gett said in a news release.
The newer variant appears to evade vaccine immunity to a greater extent than previous variants, Kwan-Gett said in the release, but vaccines and boosters still effectively lower the risk of hospitalization and death.
"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." Kwan-Gett said.
A DOH report suggest the increase in breakthrough cases may be due to the spread of the Omicron variant, increasing numbers of vaccinated persons, possible waning immunity and changes in mitigation recommendations for the public.
From Jan. 17, 2021, to Jan. 1, 2022, the state identified 123,365 breakthrough cases. Of that total, the report indicates about 3% of the patients were hospitalized and 38% were not. The report notes the status of the remaining 59% was unknown.
The report says 8% experienced no symptoms and 38% experienced some symptoms. The symptoms of the remaining 54% was unknown.
Even with a large portion of the data being unknown, the DOH release indicates most individuals with confirmed vaccine breakthrough cases "experienced only mild or no symptoms."
People ages 20-34 and 35-49 each made up 28% of breakthrough cases. Meanwhile, those 19 and younger accounted for 9%, those 50-64 made up 21%, those 65-79 made up 11% and those 80 and older made up just 3%.
Notably, women made up 53% of breakthrough cases while men made up 45%, per the report. The sex of the remaining 2% was unknown.
A higher percentage of women have gotten vaccinated than men, according to the DOH, so more women are at risk of breakthrough cases than men.
Over the same period, 919 people died due to COVID-19-related illness after experiencing a breakthrough case. The dead ranged in ages from 31 to 103, per the report, but the median age was 79.
Breakthrough cases represent around 2.5% of the over 4.5 million vaccinated population in Washington state, per the release.
In Thurston County, the state reports 67.5% (12,311) of cases affected unvaccinated individuals and 23.8% (5,106) of cases affected vaccinated individuals from February to December 2021.