The chief medical officer of BioNTech told CNBC on Wednesday that people will likely need a third shot of its two-dose Covid-19 vaccine as immunity against the virus wanes, agreeing with previous comments made by Pfizer CEO Albert Bourla.

Dr. Ozlem Tureci, co-founder and CMO of BioNTech, which developed a Covid vaccine with Pfizer, said she also expects people will need to get vaccinated against the coronavirus annually, like for the seasonal flu. That’s because, she said, scientists expect vaccine-induced immunity against the virus will decrease over time.

“We see indications for this also in the induced, but also the natural immune response against SARS-COV-2,” she said during an interview with CNBC’s Kelly Evans on “The Exchange.” “We see this waning of immune responses also in people who were just infected and therefore [it’s] also expected with the vaccines.”

Tureci’s comments come after Bourla said in an interview that aired April 15 that people will likely need a booster shot, or third dose, of the Covid-19 vaccine within 12 months of getting fully vaccinated. He also said it’s possible people will need to get additional shots each year.

Pfizer said earlier this month that its Covid-19 vaccine was more than 91% effective at protecting against the virus and more than 95% effective against severe disease up to six months after the second dose. Moderna’s vaccine, which uses technology similar to Pfizer’s, was also shown to remain highly effective at six months.

Researchers say they still don’t know how long protection against the virus lasts after six months of being fully vaccinated, though public health officials and health experts expect protection to wane after some time.

Should Americans require booster shots, the U.S. government would likely need to make arrangements with the drugmakers to supply additional doses and make plans for vaccine distribution.

On Friday, Andy Slavitt, senior advisor to President Joe Biden’s Covid response team, said the White House is preparing for the potential need for Covid-19 vaccine booster shots. He said the Biden administration has thought about the need to secure additional doses.

“I can assure you that when we do our planning, when the president orders purchases of additional vaccines as he has done and when we focus on all the production expansion opportunities that we talk about in here we very much have scenarios like that in mind,” he said at a White House press briefing.

Last week, the Biden administration’s Covid response chief science officer, David Kessler, said Americans should expect to receive booster shots to protect against coronavirus variants. He told U.S. lawmakers that currently authorized vaccines are highly protective but noted new variants could “challenge” the effectiveness of the shots.

“We don’t know everything at this moment,” he told the House Select Subcommittee on the Coronavirus Crisis.

“We are studying the durability of the antibody response,” he said. “It seems strong, but there is some waning of that, and no doubt the variants challenge ... they make these vaccines work harder. So I think for planning purposes, planning purposes only, I think we should expect that we may have to boost.”

Moderna CEO Stephane Bancel told CNBC last week that the company hopes to have a booster shot for its two-dose vaccine available in the fall.