An employee at Tesla's sprawling battery plant outside of Reno, Nevada, has tested positive for COVID-19 according to internal communications obtained by CNBC.

KRNV NBC Reno previously reported on the matter on Sunday.

Tesla's vehicle deliveries report for the first quarter of 2020 is expected within a week. Despite direct impacts of the COVID-19 pandemic on its operations in Shanghai and the U.S., the company has yet to withdraw its prior guidance, which said it should comfortably exceed 500,000 vehicle deliveries in 2020.

A memo sent to Panasonic North America employees who work in the Gigafactory on March 29 said the infected Tesla employee was sent home on Saturday, March 21, after being on-site for an hour and feeling ill. It also specified, "Tesla has a safety protocol for this scenario; this has been activated and includes 14-day quarantine for particular employees identified by their EHS team and certain cleaning measures."

The cleaning measures are of particular importance in containing COVID-19, as scientists have found that the COVID-19 coronavirus remains viable on copper surfaces up to four hours, on cardboard surfaces up to a full day, and on plastic and stainless steel for as long as two to three days.

Tesla sent a similar update to its employees overnight on March 28, according to two people who work there but asked to remain anonymous because they were not authorized to speak with press.

These people told CNBC the infected Tesla employee was sent home on the same day that Tesla and Panasonic implemented temperature-screening measures at the plant.

Panasonic had already announced plans on March 20 to wind down to minimum basic operations and suspend battery cell production there two weeks, and has granted employees 2 weeks of additional paid time off during the suspension.

After Panasonic's decision, Tesla's side of the Gigafactory stayed fully operational for about a week. Tesla finally told the county on March 26 that it also plans to reduce the number of workers at the Gigafactory by around 75%.

Panasonic could not immediately be reached for comment. Tesla did not reply to requests for further information.

Tesla CEO Elon Musk appears to have changed his tune about the novel coronavirus in recent days as some of his own employees have been infected at both Tesla and SpaceX.

On Twitter, he previously wrote that the "panic" about the pandemic was "dumb."

Musk tweet 1

In an e-mail he sent to all employees at Tesla, Musk later wrote: "My frank opinion remains that the harm from the coronavirus panic far exceeds that of the virus itself." He also incorrectly claimed that children are "essentially immune" to the virus in a tweet.

Musk tweet 2

More recently, Musk began to share research about potential but still unproven treatments for COVID-19, and to praise medical equipment makers like Medtronic.

Musk tweet 3

He has also promoted his own efforts, procuring and distributing ventilators to hospitals that need them, and promised that his companies would begin to produce ventilators, as well, donating rather than selling them all.

Tesla shares finished down 2.4% on Monday on an otherwise mostly positive day for tech stocks and the market overall.