The governor of Georgia — the state where the Centers for Disease Control and Prevention is headquartered — said Wednesday he had only just learned that the coronavirus can be spread by people who aren't showing any symptoms. Public health officials have been warning for months that asymptomatic people can transmit the virus, which appears to be a major factor behind its rapid spread around the world.

Governor Brian Kemp, in a press conference announcing a statewide stay-at-home order, said he was "finding out that this virus is now transmitting before people see signs."

"Those individuals could have been infecting people before they ever felt bad, but we didn't know that until the last 24 hours," said Kemp, a Republican. He said the head of Georgia's Department of Public Health told him this fact "was a game-changer for us."

⁉️WHAT⁉️@GOP Georgia Gov. Brian Kemp says he only just learned that asymptomatic people can transmit #COVID19. “[I]ndividuals could have been infecting people before they ever felt bad, but we didn’t know that until the last 24 hours.”🙄#coronaviruspic.twitter.com/sulhZ7N12v — Dr. Dena Grayson (@DrDenaGrayson) April 2, 2020

Kemp announced the stay-at-home order after initially resisting calls from mayors across the state to do so. His announcement also comes weeks after all 236 members of the state's legislature were advised to self-quarantine after one lawmaker tested positive for a vote. Before receiving the diagnosis, the lawmaker had shown up for a vote with the legislature despite showing symptoms of the virus.

Get Breaking News Delivered to Your Inbox

Dr. Anthony Fauci, the nation's top infectious disease expert, warned as early as January 31 that it was "absolutely the case" that asymptomatic people can transmit the virus.

The CDC, which is headquartered in Atlanta, issued guidance about asymptomatic spread more than a month ago. CDC Director Dr. Robert Redfield said this week that up to 25% of people infected with coronavirus may show no symptoms but could still spread it to others.

Under Kemp's order, all Georgia residents must remain home except for solitary outdoor exercises working essential jobs or buying necessities like groceries and medicine. The rules begin Friday and will last at least through April 13.

As of Thursday afternoon, Georgia has 5,348 confirmed coronavirus cases and 163 deaths.