An alarming increase in antibiotic-nonsusceptible invasive pneumococcal disease (NS-IPD), involving nonvaccine serotypes, has raised concerns, especially with its rise in older adults.

A study in the Journal of Infectious Diseases notes that NS-IPD incidence declined dramatically in the United States after the introduction of pneumococcal conjugate vaccines (PCVs) into the infant immunization schedule. The 7-valent PCV7, introduced in 2000, was replaced by the 13-valent PCV13 in 2010.

In fact, the authors from the CDC, Emory University School of Medicine, and Veterans Affairs Medical Center, all in Atlanta, pointed out that from 1998 through 2018, NS-IPD incidence decreased from 43.9 to 3.2 among children aged younger than 5 years and from 19.8 to 9.4 among adults aged 65 and older.

"Incidence of vaccine-type NS-IPD decreased in all age groups, while incidence of NVT NS-IPD increased in all age groups; the greatest absolute increase in NVT NS-IPD occurred among adults >65 years (2.3 to 7.2)," the authors wrote. "During 2014-18, NVTs 35B, 33F, 22F, and 15A were the most common NS-IPD serotypes."

The study concludes that NS-IPD incidence decreased following PCV7 and PCV13 introduction in the U.S., but "recent increases in NVT NS-IPD, most pronounced among older adults, have been observed. New higher valency PCVs containing the most common nonsusceptible serotypes, including 22F and 33F, could help further reduce NS-IPD."

A 2019 study in Clinical Infectious Diseases previously noted the trend.

Boston University School of Medicine and Public Health–led researchers used a retrospective design and data from two U.S. healthcare claims repositories to determine that, across study periods, IPD and all-cause hospitalized pneumonia (ACHP) rates increased with age (2-27 times higher in persons aged >75 years vs. 18-49 years) and comorbidity (4-20 times higher in high-risk vs. healthy).

"From pre- to post-PCV13 period, IPD rates declined 5%-48% and ACHP rates declined 4%-19% across age and risk groups (ACHP did not decline in persons >75)," researchers wrote. "Decline in IPD and ACHP was attenuated among older adults and those with comorbidities. Accordingly, rate ratios among at-risk and high-risk persons (vs. healthy counterparts) increased during the peri- and post-PCV13 periods compared with the pre-PCV13 period."

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