Pfizer (PFE  ) Chief Executive Officer Albert Bourla told CBS' "Face the Nation" that a fourth COVID-19 vaccine dose will be necessary in order to maintain the manageable levels of hospitalizations and mild infections the United States has experienced in the aftermath of the Omicron surge.

"Right now, the way that we have seen, it is necessary, a fourth booster right now," Bourla said in an interview Sunday. "The protection that you are getting from the third, it is good enough, actually quite good for hospitalizations and deaths. It's not that good against infections."

Bourla was referring to "early and preliminary" data, a Pfizer spokesperson told CBS, pointing to a previously announced study trialing both a fourth dose of the currently authorized COVID shot as well as one designed to target Omicron. However, preliminary results from an Israeli study released in January demonstrated that a fourth dose of the current Pfizer-BioNTech vaccine was insufficient at preventing Omicron infection; Omicron is currently the dominant COVID strain in the U.S.

Despite Bourla's stance, the need for a fourth vaccine dose, or a second booster shot, to maintain protection against COVID has mixed support. Moderna (MRNA  ) President Stephen Hoge told Business Insider on Monday that a fourth dose will likely only be necessary for elderly and immunocompromised people, not the general public.

"Is it necessary? I think that's a strong word. I think it will provide a benefit to anyone who gets its," Hoge said, referring to boosters. "Whether or not public health continues to recommend it for eyeron is a more complicated thing, because not everybody's wanting to get the first couple ones."

At the moment, there isn't enough data to definitively support a second booster for the general public. However, there have been multiple reports that demonstrate that an individual needs a minimum of three doses to protection against severe Omicron infection.

While the two executives of the top COVID vaccine developers differ on the need for more boosters, they both agree that the virus is here to stay.

Bourla told Bloomberg News last week that Pfizer expects to submit data to U.S. regulators soon on the effects of a fourth dose while it waits for the data on its Omicron-specific vaccine. He also noted that the company is developing more variant specific vaccines to help combat future strains as they mutate--similarity to how vaccines against the seasonal influenza are developed annually.

Meanwhile, Hoge told Business Insider that Moderna is optimistic that its bivalent booster, which is designed to target both Omicron and the original SARS-CoV-2 virus, could be available this year.