Potential carrier priming effect in Australian infants after 7-valent pneumococcal conjugate vaccine introduction

Table 1 Contingency table comparing the numbers of vaccine type invasive pneumococcal disease and non-vaccine type invasive pneumococcal disease cases 9 wk after single carrier primed dose of the 7-valent pneumococcal conjugate vaccine among non-Indigenous Australian infants (2001-2006)

	Two weeks after carrier primed dose of 7vPCV	2-9 wk after carrier primed dose of 7vPCV
Number of VT-IPD cases	4	1
Number of NVT-IPD cases	2	7
1P value	0.06

¹One-sided fisher’s exact test. 7vPCV: 7-valent pneumococcal conjugate vaccine; VT-IPD: Vaccine type invasive pneumococcal disease; NVT-IPD: Non-vaccine type invasive pneumococcal disease.

Table 2 Contingency table comparing the numbers of vaccine type invasive pneumococcal disease cases 9 wk after carrier primed and non-carrier primed dose of the 7-valent pneumococcal conjugate vaccine among non-Indigenous Australian infants (2001-2006)

	Two weeks after dose of 7vPCV	2-9 wk after dose of 7vPCV
Number of VT-IPD cases after carrier primed 7vPCV	4	1
Number of VT-IPD cases after non-carrier primed 7vPCV	2	6
1P value	0.08

¹One-sided fisher’s exact test. 7vPCV: 7-valent pneumococcal conjugate vaccine; VT-IPD: Vaccine type invasive pneumococcal disease.

Table 3 Invasive pneumococcal disease cases among non-Indigenous Australian children < 6 mo (2001-2010)

	Year	2001-2002			2003-2004			2005-2006			2007-2008			2009-2010
	Age	< 2 mo	2 mo-< 4 mo	4 mo-< 6 mo	< 2 mo	2 mo-< 4 mo	4 mo-< 6 mo	< 2 mo	2 mo-< 4 mo	4 mo-< 6 mo	< 2 mo	2 mo-< 4 mo	4 mo-< 6 mo	< 2 mo	2 mo-< 4 mo	4 mo-< 6 mo
VT-IPD	Vaccinated	0	1	0	0	2	0	0	7	2	1	0	0	0	1	4
	Not vaccinated	7	14	26	7	19	37	12	2	0	3	2	1	1	2	0
NVT-IPD	Vaccinated	0	0	0	0	0	0	0	5	8	2	9	14	2	8	18
	Not vaccinated	8	7	13	14	6	13	13	3	3	7	3	5	14	3	4

VT-IPD: Vaccine type invasive pneumococcal disease; NVT-IPD: Non-vaccine type invasive pneumococcal disease.