Table 3.

Respiratory Syncytial Virus (RSV)–Specific Serum Antibody Responses Before and After Inoculation and After RSV Surveillance

Group	Serum RSV-Neutralizing Antibodiesa						Serum IgG ELISA RSV F Antibodiesa
	Vaccination			RSV Surveillance			Vaccination			RSV Surveillance
	Median (IQR)b		≥4-Fold Rise, No. (%)e	Median (IQR)b		≥4-Fold Rise N (%)h	Median (IQR)b		≥4-Fold Rise, No. (%)e	Median (IQR)b		≥4-Fold Rise, No. (%)h
	Prec	Postd		Pref	Postg		Prec	Postd		Pref	Postg
Vaccine recipients (n = 21)	2.3 (2.3–2.3)	7.2 (6.1–8.3)	20 (95)	6.5i (5.2–8.4)	6.4i (5.8–10.3)	4i (21)	9.4 (7.3–10.2)	15.7 (13.9–15.7)	21 (100)	13.9i (12.5–15.7)	13.9i (13.0–15.7)	5i (26)
Placebo recipients (n = 11)	2.3 (2.3–2.3)	2.3 (2.3–2.3)	0 (0)	2.3 (2.3–2.3)	2.3 (2.3–6.0)	4 (36)	8.5 (7.2–10.1)	8.1 (6.0–9.1)	0 (0)	7.6 (6.0–8.5)	8.6 (6.2–15.7)	4 (36)

Abbreviations: ELISA, enzyme-linked immunosorbent assay; F, fusion; IgG, immunoglobulin G; IQR, interquartile range; RSV, respiratory syncytial virus.

^aSerum RSV 60% plaque reduction neutralizing titer (PRNT₆₀) was determined with complement-enhanced 60% plaque reduction neutralization assay; serum IgG titers to RSV F, with ELISA.

^bTiter results are expressed as median reciprocal log₂ values (with IQRs), determined for all participants in each group. Specimens with titers below the limit of detection were assigned reciprocal titers of 2.3 log₂ (PRNT₆₀) and 4.6 log₂ (ELISA).

^cBefore inoculation.

^dAfter inoculation at study day 56.

^eNo (%) of vaccine and placebo recipients with ≥4-fold increase between preinoculation and postinoculation antibody titers.

^f Before RSV surveillance, collected 1–31 October or on day 56 if on or after 1 October.

^gAfter RSV surveillance, collected approximately 6–12 months after inoculation (1–30 April except in 1 vaccine recipient, who had serum collected in May).

^hNo. (%) of vaccinee and placebo recipients with a ≥4-fold increase between pre– and post–RSV surveillance antibody titers,

ⁱTwo vaccine recipients had missing data at these time points.