Updated

Montana Gov. Greg Gianforte has tested positive for the coronavirus and is isolating for 10 days, his office announced on Monday. 

Gianforte, a Republican, was tested for the virus on Monday "out of an abundance of caution" after first showing symptoms on Sunday, according to a statement reported by ABC FOX Montana.  

Gianforte received his first vaccine dose late last week. But according to CDC guidance, it takes two weeks after a second vaccine dose – or two weeks after the one-dose Johnson & Johnson vaccine – for a person to be fully vaccinated. 

Gov. Greg Gianforte receives a shot of the Pfizer COVID-19 vaccine from pharmacist Drew Garton at a Walgreen's pharmacy, Thursday, April 1, 2021, in Helena, Montana.  (Thom Bridge/Independent Record via AP)

Gov. Greg Gianforte receives a shot of the Pfizer COVID-19 vaccine from pharmacist Drew Garton at a Walgreen's pharmacy, Thursday, April 1, 2021, in Helena, Montana.  (Thom Bridge/Independent Record via AP)

CORONAVIRUS IN THE US: STATE-BY-STATE BREAKDOWN

Montana's first lady has not shown any coronavirus symptoms and is awaiting her test results, the governor's office said in the announcement, and the governor's close contacts have been notified about his positive test. Gianforte was sworn into office in January and has been tested for the virus regularly since then. 

As Montana and other northern plains states were hit hard by the coronavirus late last year, former Democratic Gov. Steve Bullock put in place a statewide mask mandate. Gianforte rescinded it in February after signing a law protecting businesses from coronavirus-related liability. 

Most people who contract the coronavirus experience only mild to moderate symptoms, if any symptoms at all, and fully recover. But nevertheless, the pandemic has killed more than 500,000 Americans as it spread widely throughout the United States and the world. 

The Associated Press contributed to this report.