Table 1.

Geometric Means for Antibody Concentration, Opsonization Titers, and Antibody Potency

Serotype	Age	IgG conc (ug/ml)			Opsonic titer (OT)			Antibody potency (OT/[IgG])			Antibody needed for 1:8 Ops. Index (ng/ml)f
		GMCa	95% CId	Sige	GMTb	95% CId	Sige	GMPc	95% CId	Sige
4	Young	1.84	1.35–2.51	NSg	1735	1074–2804	p<0.01	969	612–1536	p=0.02	7.7
	Old	1.15	0.82–1.63		453	250–821		393	233–665		16.6
6B	Young	4.04	2.71–6.01	NS	1707	1046–2787	p<0.01	405	247–665	p<0.01	21.0
	Old	3.16	2.29–4.35		377	188–756		119	67–214		43.6
9V	Young	4.25	3.01–6.01	NS	3957	1921–8151	p<0.001	917	464–1810	p<0.0001	7.2
	Old	3.56	2.58–4.94		411	203–832		115	61–217		45.3
14	Young	11.45	6.65–19.70	NS	3715	1888–7309	p<0.01	343	177–665	p<0.0001	30.6
	Old	15.53	10.29–23.43		1250	717–2179		80	49–131		92.9
18C	Young	4.46	3.09–6.42	NS	1344	721–2505	p=0.09	310	174–550	p=0.02	21.5
	Old	6.33	4.57–8.77		933	500–1740		149	100–221		36.6
19F	Young	9.14	6.79–12.31	p=0.01	1254	707–2223	p<0.01	135	81–227	p=0.03	45.0
	Old	5.24	3.99–6.88		266	133–532		51	28–93		89.9
23F	Young	3.79	2.63–5.47	NS	766	377–1554	p<0.001	204	119–349	p<0.0001	41.3
	Old	3.69	2.59–5.26		147	76–285		40	25–64		160.0

^aGMC = Geometric mean concentration

^bGMT = Geometric mean titer

^cGMP = Geometric mean potency

^dCI = Confidence interval

^eSig = Statistical significance

^fAmount of antibody needed for 1:8 opsonization titer was obtained by dividing the antibody concentration (ng/ml) by the opsonization index and multiplying by 8. The median value was shown for each group.

^gNS = Not significant