Table 2.
Seroprotection rates a against study influenza A viruses by age group b and overall.
| HAI ≥ 1:40 [Proportion (95% CI)] | |||||
|---|---|---|---|---|---|
| Virus | HA Subclade | Juvenile c | Adult d | Senior e | Overall f |
| A/Swine/OH/2011 (H1N2) | delta1 | 25.0% ** (12.1, 37.9) |
34.3% ** (18.3, 50.2) |
40.9% (26.2, 55.6) |
32.2% |
| A/Swine/OH/2013 (H1N2) | delta2 | 7.0% * (0, 14.7) |
53.8% (41.6, 66.1) |
29.5% (15.9, 43.2) |
33.3% |
| A/Swine/IN/2013 (H1N1) | gamma | 55.8% (40.8, 70.8) |
58.5% (46.4, 70.5) |
56.8% (42.0, 71.6) |
53.5% |
| A/Swine/SD/2013 (H1N1) | gamma2 | 62.8% (48.2, 77.4) |
80.0% (70.2, 89.8) |
61.4% (46.8, 75.9) |
65.4% |
| A/CA/2009 (H1N1) | pdmH1 | 59.1% (44.4, 73.8) |
74.3% (59.6, 89.0) |
61.4% (46.8, 75.9) |
62.2% |
| A/Swine/MN/2010 (H3N2) | C_IV-A | 40.9% * (26.2, 55.6) |
84.6% (75.8, 93.5) |
63.6% (49.3, 78.0) |
63.7% |
| A/Swine/OH/2011 (H3N2) | C_IV-A | 15.9% * (5.0, 26.8) |
82.9% (70.2, 95.5) |
61.4% (46.8, 75.9) |
57.2% |
| A/Swine/NC/2013 (H3N2) | C_IV-A | 60.5% (45.7, 75.3) |
96.9% (92.7, 100) |
79.5% (67.5, 91.6) |
77.7% |
| A/Swine/MI/2016 (H3N2) | C_IV-A | 15.9% * (5.0, 26.8) |
63.1% (51.3, 74.9) |
40.9% (26.2, 55.6) |
42.5% |
| A/Swine/MN/2012 (H3N2) | C_IV-B | 18.6% * (6.8, 30.4) |
58.5% (46.4, 70.5) |
34.1% (19.9, 48.3) |
39.0% |
| A/Swine/NE/2012 (H3N2) | C_IV-F | 39.5% * (24.7, 54.3) |
87.7% (79.6, 95.7) |
59.1% (44.4, 73.8) |
63.3% |
| A/Swine/OH/2016 (H3N2) | human-like | 86.4% (76.1, 96.6) |
69.2% (57.9, 80.5) |
72.7% (59.4, 86.0) |
69.1% |
| A/TX/2012 (H3N2) | human | 90.9% (82.3, 99.5) |
68.6% (53.0, 84.2) |
84.1% (73.2, 95.0) |
73.3% |
a Seroprotection rate (SPR) indicated by % individuals with HAI ≥ 1:40. b Age groups constructed based on those utilized in the Tool for Influenza Pandemic Risk Assessment (TIPRA) [24]; c Individuals < 18 years old; d Individuals 18–49 years old; e Individuals ≥ 50 years old; f SPRs (%) reported for the overall group have been standardized using 2018 single-year United States population estimates reported by the U.S. Census Bureau [37]; * Within-age group SPR or lower bound of 95% confidence interval satisfies TIPRA risk classification criteria for “Lower risk”; ** Within-age group SPR or lower bound of 95% confidence interval satisfies TIPRA risk classification criteria for “Moderate risk”.