A California nurse who received the COVID-19 vaccine for more than a week has tested positive for the virus, though medical experts say the timeline isn’t unusual.

ER nurse Matthew W., who works at two different hospitals in San Diego, received the Pfizer coronavirus vaccine on Dec. 18, and initially reported arm soreness for a day, KGTV reported.

The 45-year-old nurse then felt sick after working his shift in the Covid-19 unit seven days later on Christmas Eve.

The nurse was experiencing classic symptoms such as fatigue, chills and body aches. Two days later, Matthew got tested at a drive-up hospital and his results came back positive for the coronavirus, according to the outlet.

Dr. Christian Ramers, an infectious disease specialist with Family Health Centers of San Diego, told KGTV it’s a possibility that Matthew contracted the virus before getting the shot since it takes about two weeks for the first dose of the vaccine to kick in.

“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 percent.”

Ramers added that people shouldn’t let their guard down even if they’ve gotten vaccinated, and that they should continue to follow protocols such as hand washing and wearing masks during the pandemic.

“You hear heath practitioners being very optimistic about it being the beginning of the end, but it’s going to be a slow roll, weeks to months as we roll out the vaccine,” the specialist said.