Vaccine Significantly Reduces IPD Rates in All Age Groups

The 13-valent pneumococcal conjugate vaccine (PCV13) is associated with lower rates of invasive pneumococcal disease (IPD) among children and adults, according to a recent study.

Findings from the study were presented at ID Week, which took place from October 4 to 8, 2017, in San Diego, California.
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PCV13 was first introduced in February 2010 for routine use among children younger than age 5 years. It was later recommended for use in series with 23-valent polysaccharide vaccine (PPSV23) in June 2012 among adults age 19 years or older with certain medical conditions, and in August 2014 for adults age 65 years or older.

For their study, the researchers identified 31,190 cases of IPD among residents of Active Bacterial Core (ABC) surveillance sites from July 2007 to June 2016.

Quellung, polymerase chain reaction, and whole genome sequencing were used to serotype isolates. Isolates were subsequently classified as PCV13 or non-vaccine type. Additionally, changes in incidence were estimated as percent changes with 95% confidence intervals for the pre-PCV13 period (2007-2009) and 2 post-PCV13 periods (July 2014-June 2015 and July 2015-June 2016).

Of the 31,190 cases identified, 2750 had been cases in children younger than age 5 years, and 10,930 cases had been in adults age 65 years or older. Results indicated that overall IPD rates were 33% to 62% lower in all age groups during the 2 post-PCV13 periods, compared with the pre-PCV13 period.

From 2015 to 2016, the incidence of PCV13-type had decreased by 84% in children younger than age 5 years and by 68% in adults age 65 years or older. The researchers noted that reductions in PCV13-type IPD had been driven by serotypes 19A and 7F.

Furthermore, IPD due to non-vaccine types had also significantly decreased by 27% in children younger than age 5 years and by 24% in adults age 65 years or older. There had been no significant differences in the incidence of PCV13-type IPD between the 2 post-PCV13 periods.

“IPD incidence declined among children and adults in the US following PCV13 introduction among children,” the researchers concluded. “The lack of difference in PCV13 rates between 2014-2015 and 2015-2016 suggests no measurable early impact of PCV13 introduction among adults [ages 65 years or older]. To date, we found no evidence of significant replacement disease with non-PCV13 types. Further work is needed to explain reductions in non-vaccine type disease observed in the post-PCV13 era.”

—Christina Vogt

Reference:

Pilishvili T, Gierke R, Farley M, et al. Direct and indirect impact of 13-valent pneumococcal conjugate vaccine (PCV13) on invasive pneumococcal disease (IPD) among children and adults in the U.S. Open Forum Infect Dis. 2017;4(Suppl 1):S66-S67. https://doi.org/10.1093/ofid/ofx162.158.