Sophisticated espionage is apparently occurring behind the scenes to acquire information on top coronavirus vaccine candidates.

On Thursday, Reuters reported that hackers linked to the Chinese government had targeted Moderna (MRNA 1.58%). Reuters cited an unnamed "U.S. security official" as its source. Moderna is considered by many observers to have the most promising vaccine candidate at the moment, mRNA 1273.

A hooded hacker using cellphones and a laptop.

Image source: Getty Images.

Moderna confirmed to Reuters that at some point earlier this year, the FBI alerted the company of possible "information reconnaissance activities" by a group of Chinese hackers. These activities cover a range of espionage activities, including the probing of online networks for vulnerabilities. It is not clear how successful they were, if at all, in their endeavors.

Apparently, these hackers include two unnamed Chinese citizens who were indicted last week for spying on the U.S. Among their targets were three companies -- again, unnamed -- involved in coronavirus research. One of the companies is a Massachusetts-headquartered biotech, which fits Moderna's profile.

Moderna spokesman Ray Jordan told Reuters that his company "remains highly vigilant to potential cybersecurity threats, maintaining an internal team, external support services, and good working relationships with outside authorities to continuously assess threats and protect our valuable information."

The article's source did not provide further details of the alleged hacking. The Chinese government has not yet commented on the report.

Moderna continues with its relatively rapid development of mRNA 1273, which utilizes messenger RNA to produce a response from the body's immune system. The vaccine candidate entered its phase 3 clinical trial on Monday.

Although a host of coronavirus vaccine candidates are in development, none have been approved for use.