CDC Says Vaccinated Adults Don’t Need A Booster Shot ‘At This Time’

The CDC says that anyone who’s been fully vaccinated doesn’t need a booster shot “at this time” to protect from the Delta strain or other coronavirus variants.
In a joint statement, the CDC and FDA said vaccinated adults are “protected from severe disease and death, including from the variants currently circulating in the country such as Delta”, adding that “People who are not vaccinated remain at risk”.
The statement was released just hours after Pfizer said it would seek approval for a third vaccine dose, to be administered one year after the second shot.
If a third shot isn’t necessary, why is Pfizer applying for one? Should future booster shots be free, or will they cost money like flu shots?