Table 2.
Adjusted Antibody Responses Prevaccination and at One Month Postvaccination by Hemagglutination Inhibition Against Cell-Grown Vaccine Reference Virusesa Among Recipients of High-Dose Egg-Based, Standard-Dose Egg-Based, Cell Culture–Based, and Recombinant Influenza Vaccines, Per-Protocol Populationb (n = 390)
| SD-IIV4 (n = 102) | HD-IIV3 (n = 79) | ccIIV4 (n = 106) | RIV4 (n = 103) | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Day 0c | 1 Monthd | P Value* | Day 0c | 1 Monthd | P Value* | Day 0c | 1 Monthd | P Value* | Day 0c | 1 Monthd | P Value* | |
| A/H1N1 | ||||||||||||
| Seroconversion rate | … | 5% (2%–15%) |
Ref | … | 16% (6%–37%) |
.041 | … | 24% (14%–37%) |
<.001 | … | 25% (15%–39%) |
<.001 |
| Geometric mean titer | 29.3 (20.6–41.6) |
39.4 (32.8–47.2) |
Ref | 23.2 (15.5–34.7) | 45.8 (36.4–57.7) |
.164 | 26.2 (18.5–37.0) |
58.3 (48.8–69.7) |
<.001 | 28.6 (20.2–40.6) |
65.7 (54.8–78.7) |
<.001 |
| Mean-fold rise in GMT | … | 1.5 (1.2–1.8) |
Ref | … | 1.7 (1.4–2.1) |
.164 | … | 2.2 (1.8–2.6) |
<.001 | … | 2.4 (2.0–2.9) |
<.001 |
| A/H3N2 | ||||||||||||
| Seroconversion rate | … | 28% (16%–43%) |
Ref | … | 50% (32%–68%) |
.012 | … | 24% (14%–38%) |
.571 | … | 49% (34%–63%) |
.007** |
| Geometric mean titer | 58.9 (43.7–79.5) |
107.4 (84.7–136.1) |
Ref | 26.3 (18.6–37.0) | 115.4 (85.1–156.3) |
.617 | 49.0 (36.5–67.7) |
100.9 (80.0–127.2) |
.610 | 56.5 (41.9–76.1) |
161.3 (127.4–204.1) |
.001 |
| Mean-fold rise in GMT | … | 2.3 (1.8–2.9) |
Ref | … | 2.5 (1.8–3.3) |
.617 | … | 2.1 (1.7–2.7) |
.610 | … | 3.4 (2.7–4.3) |
.001 |
| B/Victoria | ||||||||||||
| Seroconversion rate | … | 4% (4%–13%) |
Ref | … | 11% (3%–31%) |
.126 | … | 8% (3%–18%) |
.284 | … | 21% (12%–35%) |
.001 |
| Geometric mean titer | 32.4 (25.5–41.1) |
48.7 (41.7–57.0) |
Ref | 46.0 (34.8–60.8) | 54.2 (44.3–66.3) |
.263 | 44.4 (35.1–56.1) |
57.6 (49.4–67.1) |
.041 | 40.4 (31.8–41.2) |
78.8 (67.5–92.0) |
<.001 |
| Mean-fold rise in GMT | … | 1.2 (1.0–1.4) |
Ref | … | 1.4 (1.4–1.7) |
.263 | … | 1.4 (1.2–1.7) |
.041 | … | 2.0 (1.7–2.3) |
<.001 |
| B/Yamagata | ||||||||||||
| Seroconversion rate | … | 3% (1%–11%) |
Ref | … | 3% (1%–15%) |
.719 | … | 9% (4%–20%) |
.042 | … | 36% (24%–51%) |
<.001 |
| Geometric mean titer | 40.3 (30.7–52.9) |
54.5 (45.5–65.4) |
Ref | 28.2 (20.2–39.2) | 48.0 (38.1–60.4) |
.237 | 59.0 (49.3–70.5) |
62.0 (50.1–76.7) |
.407 | 48.5 (37.0–63.6) |
100.8 (84.0–120.8) |
<.001 |
| Mean-fold rise in GMT | … | 1.3 (1.1–1.6) |
Ref | … | 1.2 (0.9–1.5) |
.267 | … | 1.4 (1.2–1.7) |
.407 | … | 2.4 (2.0–2.9) |
<.001 |
Abbreviations: ANOVA, analysis of variance; ccIIV4, cell culture–based inactivated influenza vaccine represented by Flucelvax Quadrivalent by Seqirus; GMT, geometric mean titer; HCP, health care personnel; HD-IIV3, high-dose trivalent inactivated influenza vaccine represented by Fluzone High-Dose by Sanofi Pasteur; HI, hemagluttination inhibition; MFR, mean fold rise; RIV4, recombinant inactivated influenza vaccine represented by Flublok Quadrivalent by Sanofi Pasteur; SCR, seroconversion rate; SD-IIV4, standard-dose quadrivalent inactivated influenza vaccine represented by Fluzone Quadrivalent by Sanofi Pasteur.
Hemagglutination inhibition antibody titers were measured against the following cell-grown vaccine reference viruses: A/Kansas/14/2017 (H3N2), A/Idaho/07/2018 (H1N1)pdm09 (A/Brisbane/02/2018-like), B/Colorado/06/2017 (B/Victoria), and B/Phuket/3073/2013 (B/Yamagata) viruses.
The per-protocol population comprised eligible HCP who received study vaccine and had sera drawn and tested at around 1 month postvaccination within the protocol-specified acceptable time interval (20–62 days postvaccination).
Day 0 GMT adjusted for study site with 99.3% CIs.
One-month outcomes adjusted for the log of prevaccination titers and study site with 99.3% CIs.
P values based on logistic regression (SCR) and ANOVA (GMT and MFR) models adjusted for study site and the log of prevaccination titers comparing HD-IIV3, ccIIV4, and RIV4 with SD-IIV4 as the referent group. A Bonferroni correction for multiple comparisons was prespecified in the protocol for 7 comparisons of different combinations of influenza vaccines during the 2 trial seasons (3 presented here and 4 in another report). Therefore, statistical significance was defined at P = .007.
The P value was .0069, which met the threshold for significance before rounding.