The Advisory Committee on Immunization Practice (ACIP) is currently recommending that a dose of PCV13 (13-valent pneumococcal conjugate vaccine [Prevnar 13]; Pfizer) be followed by a dose of PPSV23 (23-valent pneumococcal polysaccharide vaccine [Pneumovax 23]; Merck) in all adults aged ≥65 years who have not previously received pneumococcal vaccine, and in patients aged ≥2 years who are at high risk for pneumococcal disease due to underlying medical conditions. The intervals between PCV13 and PPSV23 differed based on age, risk group, and the order of the two administered vaccines.

On June 25, 2015, the ACIP revised the recommended interval between PCV13 and PPSV23 (PCV13-PPSV23 sequence) from 6–12 months to ≥1 year for immunocompetent adults aged ≥65 years. The two vaccines should not be co-administered. If a dose of PPSV23 is inadvertently given earlier than the recommended interval, the dose need not be repeated. The intervals recommended for all other age and risk groups remain the same.

In August 2014, the ACIP recommended adults aged ≥65 years receive PCV13 first, followed by PPSV23 ≥8 weeks later if they had immunocompromising conditions, functional or anatomic asplenia, CSF leaks, or cochlear implants. In addition, all adults aged ≥65 years who received PPSV23 were recommended to receive a dose of PCV13 ≥1 year after their PPSV23 dose (PPSV23-PCV13 sequence). The difference in the recommended interval depending on the order of the two vaccines given complicated the recommendation and caused implementation changes for this age group, the Committee reported.The ACIP evaluated whether existing evidence would support changing the recommended interval for the PCV13-PPSV23 sequence for immunocompetent adults aged ≥65 years to a ≥1 year interval, and if it would be in harmony with the recommended interval for the PPSV23-PCV13 sequence in the same age group.