Pennsylvania Gov. Tom Wolf tested negative for COVID-19 on Wednesday and Thursday evening after receiving a positive test result earlier in the week.

Wolf, whose positive test result was announced Wednesday, had no symptoms and had been following precautions, including masking, when he underwent PCR testing Tuesday as part of routine surveillance. His wife did not test positive.

The governor tested negative in subsequent tests administered Wednesday and Thursday, his office announced Friday.

PCR is a molecular test that can detect minute amounts of virus in a nasal swab or saliva sample.

Given the timing of Wolf’s positive and negative tests, state epidemiologist Sharon Watkins speculated that he had an asymptomatic infection that was almost cleared by the time he had a positive test.

“These tests are considered the gold standard among tests for COVID-19,” Watkins said. “It is possible that Governor Wolf was at the end of his infectious period when the first test was conducted.”

Based on studies of PCR testing, it is also possible that the governor had a false positive — a false alarm.

Despite their negative test results, the governor and his wife will continue to self-quarantine, following federal and Pennsylvania Health Department guidelines for asymptomatic cases, Wolf said on Twitter.