Table 3.
Antibody responses pre- and post-vaccination with quadrivalent recombinant protein influenza vaccine (RIV4) and quadrivalent inactivated egg-based influenza vaccine (IIV4) against influenza vaccine reference virusesa among participants who received influenza vaccine infrequently (0-2 seasons) or frequently (3-5 seasons) during the prior five seasonsb.
| Frequency of vaccinations in prior five influenza seasons b , c | IIV4 |
RIV4 |
Post-vaccination GMT RIV4 vs IIV4 (95% CI) | P-value | ||
|---|---|---|---|---|---|---|
| N | Post-vaccination GMT (95% CI) | N | Post-vaccination GMT (95% CI) | |||
| Influenza A(H1N1)pdm09 | ||||||
| Frequent (3-5) | 151 | 71.8 (60-85) | 148 | 159.4 (134-190) | 2.2 (1.7 - 2.8) | <0.001 |
| Infrequent (0-2) | 61 | 120.1 (91-158) | 55 | 238.8 (179-318) | 2.0 (1.3 - 3.0) | <0.001 |
| Influenza A(H3N2), Egg-based | ||||||
| Frequent (3-5) | 151 | 149.5 (128-175) | 148 | 216.6 (185-253) | 1.4 (1.2 - 1.8) | 0.001 |
| Infrequent (0-2) | 61 | 161.9 (127-207) | 55 | 350.0 (271-453) | 2.2 (1.5 - 3.1) | <0.001 |
| Influenza A(H3N2), Cell-based | ||||||
| Frequent (3-5) | 151 | 80.1 (70-92) | 148 | 166 (144-192) | 2.1 (1.7 - 2.5) | <0.001 |
| Infrequent (0-2) | 61 | 82.6 (66-103) | 55 | 269 (212-340) | 3.3 (2.3 - 4.5) | <0.001 |
| Influenza B (Victoria) | ||||||
| Frequent (3-5) | 151 | 67.8 (57-80) | 148 | 82.6 (69-98) | 1.2 (1.0 - 1.5) | 0.108 |
| Infrequent (0-2) | 61 | 113.1 (87-148) | 55 | 113.5 (86-150) | 1.0 (0.7 - 1.5) | 0.985 |
| Influenza B (Yamagata) | ||||||
| Frequent (3-5) | 151 | 91.9 (78-108) | 148 | 167.4 (142-198) | 1.8 (1.4 - 2.3) | <0.001 |
| Infrequent (0-2) | 61 | 151.3 (117-196) | 55 | 296.6 (226-389) | 2.0 (1.3 - 2.9) | <0.001 |
Abbreviations: Quadrivalent inactivated influenza vaccine (IIV4), Quadrivalent recombinant influenza vaccine (RIV4), Geometric mean titre (GMT).
Influenza vaccine reference viruses: A/Brisbane/02/2018 (H1N1)pdm09, A/Kansas/14/2017 (H3N2), B/Colorado/06/2017 (Victoria lineage), and B/Phuket/3073/2013 (Yamagata lineage) vaccine antigens.
Frequency of vaccinations were categorised as frequent and infrequent: frequently vaccinated, defined as receiving influenza vaccine in 3-5 of the past five seasons, compared with those infrequently vaccinated, defined as receiving influenza vaccine in ≤2 of the past five seasons.
GMT and GMT ratios were calculated by linear mixed models adjusting for age, hospital, and immunocompromised status. Statistically significant findings are shown in bold.