MOSES LAKE — Two employees at Samaritan Healthcare have tested positive for COVID-19 after receiving both shots of the Pfizer-BioNTech coronavirus vaccine.

Gretchen Youngren, Samaritan executive director of development and communication, said it’s unknown whether the two employees had the original strain of the virus or a variant.

“Because of timing, the first employee’s specimen was out of the window of opportunity for variant testing as conducted by the Washington Department of Health,” Youngren wrote in an email. “The second employee had a viral load too low to be tested for variants.”

There’s no evidence either patient infected anyone else, Youngren said. Neither showed symptoms and both have returned to work after a mandatory quarantine.

As of Tuesday, 267 Samaritan employees had received the full dose of vaccine, she said. The Pfizer vaccine requires two shots.

“This demonstrates that while the vaccine is very effective, it is not a 100% guarantee,” Youngren wrote. “Another reason why it is important to (wear a) mask and socially distance, especially with new variants that may still lead to infection, even though the illness may be mild.”