COVID vaccine uptake has plateaued in many parts of the world, including in the U.S., where 68.1% of the population is fully vaccinated.

Among the fully vaccinated, just 49% have gotten their first booster and 39% of those individuals have received their second booster dose.

Improving those booster numbers won’t be easy, according to Pfizer (PFE) CEO Albert Bourla. In fact, Bourla is anticipating resistance to public health recommendations because of the constantly-evolving virus.

“The health authorities will make those recommendations while they see what is the severity of the strains that are available,” Bourla said at Yahoo Finance’s 2022 All Markets Summit (video above). “But in many cases, I do not expect that people will comply with these recommendations as they did in maybe the first months of the pandemic when people were really scared. Complacency will get in the way, so I see that the volumes of people that will be getting the vaccine will be less.”

Most health experts have agreed that a yearly COVID booster will be necessary to keep case counts low and minimize the severity of symptoms, much like the flu shot.

“I think with the right vaccines, we can prevent infections to hospitalizations to deaths and severe diseases,” Bourla said. “The vaccine has shown that death and hospitalization, the prevention is very high. When it comes to infections, the bar is a little lower.”

The uptake for flu shots isn’t very high either. According to the CDC, just 51.4% of U.S. adults received their flu shot during the 2021-22 flu season, a 0.7% decrease from the prior year.

“I think that the goal is to bring vaccines so that they can last a year,” Bourla said. “I think that will simplify things because I believe that people will not be that diligent to do the vaccinations as they are tired of making too many vaccines and they want stability. But if we have a yearly vaccine, which is something that people are used to like the flu, for example, this is something that will take a significant amount of people to be able to get it.”