Democratic presidential hopeful former Vice President Joe Biden (C) and Vermont Senator Bernie Sanders shake hands ahead of the third Democratic primary debate of the 2020 presidential campaign season hosted by ABC News in partnership with Univision at Texas Southern University in Houston, Texas on September 12, 2019.

Joe Biden and Bernie Sanders haven't aired campaign television ads in nearly two weeks as the coronavirus spreads and dominates headlines.

The Democratic presidential rivals haven't aired an ad on TV since March 17, according to data compiled by Advertising Analytics. Instead, they are focusing on digital advertising.

The move comes as both campaigns have eliminated in-person campaigning, opting instead to address supporters through virtual events.

Since last week, Biden has been spent more on Facebook ads, investing just over $1 million into spots that appear on the social media platform, according to Facebook's ad archive. Sanders, who has been a prolific online fundraiser, has put up only $190,000 on Facebook and none of the ads he's purchased is currently active.

Sanders' campaign, despite being behind Biden in the delegate count, has publicly called on the Vermont senator's supporters to help them raise money for charities fighting the coronavirus.

Biden has used his digital ads to go hard after President Donald Trump over his handling of the coronavirus crisis. One of the advertisements, which also was published on Biden's Twitter feed, portrays the former vice president as a leader who is better positioned to comfort the country during a time of tragedy and upheaval.

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While Biden's campaign itself hasn't been on TV, a super PAC supporting him, Unite the Country, has been hammering Trump on the airwaves with an ad depicting past presidents such as Barack Obama and Ronald Reagan, contrasting their leadership with Trump's. Advertising Analytics said the ad has been aired at least 365 times. Priorities USA, another super PAC backing Biden, has also been airing TV ads against Trump as part of a recent $6 million ad buy.

Jen O'Malley Dillon, Biden's new campaign manager, sent a memo to supporters Thursday that outlines the organization's digital plans. Dillon said the campaign is still reaching out to Wisconsin primary voters, who are still scheduled to vote on April 7, despite the coronavirus' spread. The campaign is encouraging voters in that state to use mail-in ballots as an alternative to in-person voting.

Dillon also stressed the importance of digital fundraising, since the campaign has halted in-person donor events.

The campaign told supporters in an email on Friday that it raised over $30 million online during the month of March, which saw Biden surge ahead of Sanders thanks to primary victories in delegate-rich states such as Texas, Illinois and Michigan.

Biden and Sanders may also be getting a boost from a former rival. Sen. Elizabeth Warren's former presidential campaign published a list of tech companies they worked with when she was running in the primary. According to a blog post, the hope is "that other Democratic candidates and progressive causes will use the ideas and code we developed to run stronger campaigns and help Democrats win."