Table 3.
Immune response to RSV F-protein vaccine in pregnant women and kinetics of antibodies among maternal and infant participants, per-protocol immunogenicity population.
| Parameter: | Palivizumab competing antibody | Anti-F IgG | RSV/A micro-neutralization titer | RSV/B micro-neutralization titer | ||||
|---|---|---|---|---|---|---|---|---|
| Timepoint, Endpoint | Placebo | RSV F Vaccine | Placebo | RSV F Vaccine | Placebo | RSV F Vaccine | Placebo | RSV F Vaccine |
| Screening (-28 - 0) – mother, n | 1446 | 2776 | 1446 | 2776 | 489 | 879 | 489 | 878 |
| GMC/GMEU/GMT (95% CI) | 13 (13, 14) | 13 (13, 13) | 569 (545, 594) | 568 (551, 586) | 741 (691, 794) | 714 (677. 753) | 605 (552, 664) | 563 (525, 605) |
| Day 14 (± 2 days) – mother, n | 1370 | 2643 | 1370 | 2642 | 92 | 94 | 92 | 94 |
| GMC/GMEU/GMT (95% CI) | 13 (12, 13) | 162 (158, 167) | 563 (539, 587) | 10568 (10250, 10897) | 654 (565, 756) | 1622 (1384, 1900) | 845 (670,1066) | 2419 (1934, 3025) |
| GMFR (95%CI) | 0.94 (0.92, 0.96) | 12.39 (11.98, 12.81) | 0.99 (0.97, 1.02) | 18.59 (17.84, 19.36) | 0.98 (0.92, 1.05) | 2.35 (2.06, 2.68) | 0.96 (0.88, 1.04) | 3.00 (2.56, 3.51) |
| Delivery – mother, n | 1446 | 2776 | 1446 | 2776 | 489 | 879 | 489 | 879 |
| GMC/GMEU/GMT (95% CI) | 12 (12, 13) | 130 (127, 133) | 525 (504, 547) | 8165 (7945, 8391) | 663 (616, 713) | 1589 (1488, 1654) | 534 (487, 586) | 1213 (1138, 1293) |
| GMFR (95%CI) | 0.92 (0.90, 0.94) | 9.94 (9.64, 10.25) | 0.92 (0.90, 0.95) | 14.37 (13.86, 14.90) | 0.89 (0.86, 0.93) | 2.20 (2.10, 2.30) | 0.88 (0.84, 0.93) | 2.15 (2.06, 2.25) |
| CCord blood – infant, n | 1337 | 2547 | 1343 | 2557 | 424 | 759 | 423 | 758 |
| GMC/GMEU/GMT (95% CI) | 15 (14, 15) | 136 (132, 139) | 752 (719, 785) | 9501 (9224, 9787) | 732 (674, 796) | 1704 (1602, 1813) | 607 (544,678) | 1291 (1198, 1392) |
| Cord to maternal ratio, n | 1316 | 2508 | 1322 | 2517 | 421 | 752 | 420 | 751 |
| Cord to maternal ratio | 1.18 (1.15, 1.22) | 1.04 (1.02, 1.06) | 1.43 (1.38, 1.47) | 1.17 (1.14, 1.19) | 1.12 (1.07, 1.18) | 1.08 (1.04, 1.13) | 1.14 (1.08, 1.20) | 1.07 (1.03, 1.12) |
| Half-life in infants | 192.16 (150.85, 264.64) | 49.11 (47.94, 50.34) | 116.73 (97.28, 145.90) | 38.33 (37.47, 39.22) | 39.76 (37.50, 42.31) | 34.46 (33.28, 35.73) | 37.79 (32.48, 45.19) | 31.31 (27.87, 35.72) |
| R2 | 0.0615 | 0.5298 | 0.0854 | 0.5551 | 0.5213 | 0.6289 | 0.4370 | 0.5881 |
CI = confidence interval; GMC = geometric mean concentration; GMEU = geometric mean ELISA units; GMFR = geometric mean fold rise; GMT = geometric mean titer; n = participants analyzed per timepoint; PCA= palivizumab-competitive antibodies; SCR = seroconversion rate.
The per-protocol immunogenicity population (PP-IMM) was the primary population used for immunogenicity analyses.
The PP-IMM for maternal subjects was all maternal subjects who received the test article and regimen to which they were randomized, provided baseline and delivery (up to 72 hours post-delivery) serology data, and had no major protocol deviations affecting the primary immunogenicity outcomes as determined and documented by Novavax prior to database lock and unblinding.
The PP-IMM for infant subjects was all infant subjects who: a) were ≥ 37 weeks gestational age at birth, b) were born to maternal subjects who received a study injection as randomized and ≥ 2 weeks prior to delivery, c) had provided a cord blood specimen (or infant blood sample by venipuncture or heel stick within 72 hours of delivery as an acceptable substitute), d) had not received prophylactic treatment with palivizumab between birth and Day 180 after delivery, and e) had no major protocol deviations affecting the primary immunogenicity outcomes as determined and documented by Novavax prior to database lock and unblinding.
PCA was measured in terms of GMC (μg/mL). Anti-F IgG was measured in terms of geometric means ELISA units. RSV microneutralization titers measured in International Units (IU).