Impact of 13-Valent Pneumococcal Conjugate Vaccine on Invasive Pneumococcal Disease, U.S, 2010-11

Background: Pediatric use of 7-valent pneumococcal conjugate vaccine (PCV7) dramatically reduced the incidence of invasive pneumococcal disease (IPD) among children (direct effects) and adults (indirect effects). U.S. introduction of 13-valent pneumococcal conjugate vaccine (PCV13) began in March 2010. We evaluated the impact of routine PCV13 use on rates of IPD among children and adults.

Methods: IPD cases (isolation of pneumococcus from sterile sites) were identified through 10 Active Bacterial Core surveillance (ABCs) sites. Isolates were serotyped at reference laboratories. To distinguish effects of PCV13 from residual effects of PCV7, we focused on the 6 serotypes (PCV6) included in PCV13 that are not included in PCV7. We compared quarterly rates (cases per 100,000) of IPD in 2011 with baseline rates from 2006-08 (excluding 2009, year of influenza pandemic). To account for multiple comparisons, we considered P<0.0025 as significant.

Results: During 2006-2008 and 2011, 12,181 and 3,523 cases of IPD were identified, respectively; 88% of isolates had serotype results. Among children <5 years old, a statistically significant reduction (65%) in the rate of PCV6-type IPD was evident by the first quarter of 2011. By the second quarter of 2011, reductions were evident among adults ≥65 years old. By the fourth quarter of 2011, rates of PCV6-type IPD had declined by nearly 90% among children <5 years old and by 45-64% among all adult age groups (Table). Reductions were driven primarily by declines in serotypes 19A and 7F.

Table. Change in rates, expressed as cases per 100,000, of PCV6-type IPD by age and quarter, 2011 vs. baseline (2006-2008).

	Jan-Mar			Apr-Jun			Jul-Sep			Oct-Dec
Age, yrs	Baseline	2011	% Change	Baseline	2011	% Change	Baseline	2011	% Change	Baseline	2011	% Change
<5	16.5	5.7	-65*	12.8	2.9	-77*	6.4	1.7	-73*	15.8	1.9	-88*
5-17	2.1	1.5	-29	1.7	0.8	-53	0.7	0.2	-71	1.9	0.9	-53
18-49	5.2	3.7	-29	3.1	2.0	-35	1.5	1.0	-33	3.9	1.4	-64*
50-64	10.8	11.9	10	7.4	5.9	-20	3.5	2.4	-31	9.7	5.3	-45*
>65	19.4	13.7	-29	11.9	6.7	-44*	3.9	3.4	-13	18.4	7.1	-61*

*P<0.0025

Conclusion: PCV13 introduction was followed by rapid and dramatic reductions in the incidence of IPD caused by the 6 new serotypes included in the vaccine. Indirect effects of PCV13 use in children are evident in all adult age groups.