By MORGAN WINSOR

Over 100 people in Washington state have tested positive for COVID-19 more than two weeks after becoming fully vaccinated against the disease, officials said.

The Washington State Department of Health is investigating reports of the so-called breakthrough cases, which it said are expected with any vaccine.

Out of the 1.2 million people who are fully vaccinated against COVID-19 in Washington, epidemiologists have reported evidence of 102 breakthrough cases in 18 counties since Feb. 1, representing less than 0.01% of all fully vaccinated individuals in the northwestern U.S. state. Most cases were patients who experienced only mild symptoms, if any, according to a press release from the Washington State Department of Health.

However, at least eight people with breakthrough cases have been hospitalized. The Washington State Department of Health is also investigating two potential breakthrough cases where the individuals died. Both patients were over 80 years old and suffered from underlying health issues.

The Washington State Department of Health said further investigation will help identify patterns among the breakthrough cases, such as if a variant of the novel coronavirus may have caused the infection.

A breakthrough case is confirmed with a positive polymerase chain reaction (PCR) test or a positive antigen test in an individual more than two weeks after they have received their final dose of a COVID-19 vaccine, according to the Washington State Department of Health.

"Finding evidence of vaccine breakthrough cases reminds us that, even if you have been vaccinated, you still need to wear a mask, practice socially distancing, and wash your hands to prevent spreading COVID-19 to others who have not been vaccinated," Dr. Umair Shah, Washington state's secretary of health, said in a statement Tuesday.

Large-scale clinical studies found that COVID-19 vaccines reduced the risk of contracting the disease in vaccinated individuals by up to 95%, compared with those who were not vaccinated. However, the vaccines are not 100% effective in preventing infection and thus a small percentage of breakthrough cases can be anticipated, according to the Washington State Department of Health.

"It is important to remember that every vaccine on the market right now prevents severe disease and death in most cases," Shah said. "People should still get vaccinated as soon as they are eligible, and encourage friends, loved ones, and co-workers to do the same."

More than 30.3 million people have been diagnosed with COVID-19 in the United States and over 550,000 of them have died, according to data compiled by Johns Hopkins University.

Washington state has registered at least 363,235 confirmed cases and 5,237 deaths. So far, more than 16% of the Evergreen State's population is fully vaccinated against COVID-19, according to Johns Hopkins data. (ABC News)

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