Washington (CNN) Transportation Security Administration head David Pekoske held a call Monday with TSA security directors from airports across the country where they discussed impacts of the shutdown, including an increase in call outs and how to ensure officers show up to work, two sources familiar with the call told CNN.

The call included TSA Administrator David Pekoske and top-ranking field officials, according to one of the sources, who listened to the call.

On Friday, CNN reported that hundreds of TSA screeners have called out from their shifts from at least four major airports since the shutdown began in December. One federal official dubbed it a "blue flu," nodding to the blue shirts worn by TSA officers, while union officials say officers can't afford to work unpaid.

On the call, Pekoske said security standards would not be lessened and that TSA should be transparent with the public about staffing levels and callouts so that travelers know whether to expect longer security lines, the sources said.

In response to the increase in call outs, TSA is starting to track absences on a national level, according to the source who listened in. Officials asked the agency's regional leaders to provide suggestions for how to incentivize employee attendance. Some airports are granting future time off as an incentive, according to one of the sources.

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