Even though the biopharmaceutical company Pfizer has announced that it might be time to consider giving a third dose of its coronavirus vaccine to people, many doctors and public health officials argue that it's more beneficial to get shots into the arms of the unvaccinated right now than to boost those who are already fully vaccinated.

"It's wonderful to have a booster approved for emergency use authorization on the shelf -- ready to go any time we need it. But I do not think we need it right now," Dr. William Schaffner, a professor at Vanderbilt University School of Medicine and medical director of the National Foundation for Infectious Diseases, told CNN on Friday.

On Thursday, the companies Pfizer and BioNTech announced that a third dose of their coronavirus vaccine, given six months after a second dose, appears to preserve "the highest levels of protection" in those who were vaccinated.

The companies made their announcement without releasing any new data, but noted plans to publish new information soon. A Pfizer spokesperson later told CNN that the company plans to file for emergency use authorization for a booster dose with the US Food and Drug Administration in August.