(NEXSTAR) – The chief health officer for Delta Air Lines said this week that the carrier’s decision to implement a $200 surcharge for unvaccinated employees has convinced a “huge” portion of the workforce to change their minds about the jab.

Dr. Henry Ting, speaking during a Thursday media briefing with the Infectious Diseases Society of America, said that approximately 20,000 Delta team members had not been vaccinated as of Aug. 25, when CEO Ed Bastian announced a monthly surcharge for unvaccinated employees on Delta’s healthcare plan.

“Just within the two weeks of the announcement, we’ve seen nearly 20%, or one-fifth, of that 20,000 decide to get the vaccine,” said Ting. He added that Delta did not observe any turnover or resignations as a result of the new policy.

Prior to Bastian’s announcement, around 74% of Delta’s workforce had been vaccinated. That number now sits at around 78%.

The increase may not sound like much, but Ting says it’s a “huge number” when taking into consideration the initial reluctance of those 20,000 unvaccinated employees.

“That last 4% is very different from the first 4%,” he said.

CEO Ed Bastian publicly announced Delta’s surcharge policy in late August, saying it was “necessary to address the financial risk the decision to not vaccinate is creating for our company.” (Yuichi Yamazaki/Getty Images)

CEO Ed Bastian publicly announced Delta’s surcharge for unvaccinated employees on Aug. 25, in a memo to colleagues also published at Delta’s website.

“Beginning Nov. 1, unvaccinated employees enrolled in Delta’s account-based healthcare plan will be subject to a $200 monthly surcharge,” reads one of the bulletpoints in Bastian’s memo. “The average hospital stay for COVID-19 has cost Delta $50,000 per person. This surcharge will be necessary to address the financial risk the decision to not vaccinate is creating for our company.”

In the memo, Bastian added that every Delta employee who had been hospitalized with COVID-19, up to that point, had been unvaccinated.

Delta is currently not among the several major carriers that have implemented vaccine mandates for employees, though the airline continues to strongly encourage vaccination for its entire workforce.

The airline has also mandated that all new hires be vaccinated, a decision which has not deterred candidates applying for Delta’s thousands of available jobs, according to Ting.