Eight days after receiving Pfizer’s COVID-19 vaccine, a 45-year-old nurse in California has tested positive for coronavirus, reported an ABC News affiliate on Wednesday.

Matthew W, who is an emergency room nurse at two different local hospitals, said in a Facebook post on December 18 that he had received the Pfizer vaccine. He told ABC News affiliate that he suffered no other side effects apart from having a sore arm for a day.

After working a shift in the COVID-19 unit, Matthew felt sick, the report said. His body started aching and he experienced fatigue.

He went to a drive-up hospital testing site and tested positive for COVID-19 the day after Christmas, the report said.

Christian Ramers, an infectious disease specialist with Family Health Centers of San Diego, told the ABC News affiliate that this situation is not as unusual as it may seem.

“We know from the vaccine clinical trials that it’s going to take about 10 to 14 days for you to start to develop protection from the vaccine,” Ramers said.

“That first dose we think gives you somewhere around 50%, and you need that second dose to get up to 95%,” he added.

Ramers said that Matthew’s story is the evidence that even with vaccines, the pandemic isn’t going to turn around immediately.

The expert said it is possible that the patient was infected with the novel coronavirus before he got the shot.

Matthew says he’s feeling better since his symptoms peaked on Christmas but still feels fatigued.