For those 65 years of age or older receiving the vaccine for the first time:
You will need one to two doses of the vaccine depending on the manufacturer. Two doses usually require a one-year separation. This may vary for patients with immunocompromising conditions, cochlear implants and cerebrospinal fluid leaks. See the source's table on page 2 for details, but the minimum interval between shots is 8 weeks. Ultimately, those with such conditions should consult their doctor.
For those who had only one pneumonia vaccine in their lifetime:
You may now need an additional vaccination.
For those who had the pneumonia vaccine before they were 65:
You may now need one or two additional vaccinations.
*Source: Centers for Disease Control and Prevention https://www.cdc.gov/vaccines/vpd/pneumo/downloads/pneumo-vaccine-timing.pdf