WASHINGTON (NewsNation Now) — An executive order goes into effect Monday mandating that all federal employees receive a COVID-19 vaccination or seek an exemption, possibly impacting TSA workers who are already dealing with a busy holiday travel week.

With the mandate about to take effect, no one has any hard numbers as to how many personnel remain unvaccinated, so the effect on airport staffing, if any, is hard to anticipate.

Union representatives and some Capitol Hill staffers estimate that as much as 10% of TSA personnel are as yet unvaccinated. Customs and border protection agents are also lagging in their vaccinations, according to sources.

Despite this, the Biden administration remains optimistic about the mandate.

“What we have seen is there is a surge in attestations and vaccination as we get closer to the deadline, which is certainly encouraging, but we want to have the final data Monday,” White House press secretary Jen Psaki said.

It is expected the public will be coming into contact with TSA workers more than at any time since the pandemic began, with Thanksgiving being the busiest travel week of the year.

The Transportation Security Administration says it is ready to handle the surge.

Administrator David Pekoske said he didn’t think the vaccine mandate going into effect for TSA agents would have any effect on staffing for Thanksgiving week.

“In fact, implementation of the mandate will make travel safer and healthier for everyone,” he said. “So, we see quite a significant increase in the number of our officers that are vaccinated, and I’m very confident that there will be no impact for Thanksgiving.”

However, the agency is already facing staffing shortages, so any loss of personnel due to the vaccine mandate would aggravate the situation.