Table 2.
Seasonal Incidence and Attack Rates of RSV-ARI for Season 1 (1 October 2022–30 April 2023) and Season 2 (1 October 2023–30 April 2024)
| Season 1 (1 October 2022–30 April 2023) | Season 2 (1 October 2023–30 April 2024) | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Participants, No.a | RSV-ARI, No.b | PYc | IR per 1000 PY (95% CI)d | Attack Rate, % (95% CI)e | Participants, No. | RSV-ARI, No. | PY | IR per 1000 PY (95% CI) | Attack Rate, % (95% CI) | |
| Overall | ||||||||||
| Unstandardized | 7501 | 112 | 4041.56 | 27.71 (22.82–33.34) | 1.49 (1.23–1.79) | 7397 | 112 | 4244.75 | 26.39 (21.73–31.75) | 1.51 (1.25–1.82) |
| Standardized age/gender-adjusted IRf | … | … | … | 26.46 (20.81–32.11) | … | … | … | … | 25.32 (19.65–30.98) | … |
| Age at start of season, y | ||||||||||
| 18–49 | 4169 | 69 | 2239.15 | 30.82 (23.98–39.00) | 1.66 (1.29–2.09) | 3929 | 49 | 2251.24 | 21.77 (16.10–28.78) | 1.25 (.92–1.65) |
| 50–59 | 2064 | 22 | 1117.80 | 19.68 (12.33–29.80) | 1.07 (.67–1.61) | 1989 | 29 | 1146.82 | 25.29 (16.94–36.32) | 1.46 (.98–2.09) |
| 60–64 | 1268 | 21 | 684.61 | 30.67 (18.99–46.89) | 1.66 (1.03–2.52) | 1479 | 34 | 846.68 | 40.16 (27.81–56.12) | 2.30 (1.60–3.20) |
| Gender | ||||||||||
| Male | 2145 | 27 | 1158.68 | 23.30 (15.36–33.90) | 1.26 (.83–1.83) | 2132 | 33 | 1228.08 | 26.87 (18.50–37.74) | 1.55 (1.07–2.17) |
| Female | 5356 | 85 | 2882.89 | 29.48 (23.55–36.46) | 1.59 (1.27–1.96) | 5265 | 79 | 3016.67 | 26.19 (20.73–32.64) | 1.50 (1.19–1.87) |
| Race and ethnicity | ||||||||||
| African American | 141 | 0 | 78.20 | 0.00 (.00–47.17) | 0.00 (.00–2.58) | 136 | 2 | 78.52 | 25.47 (3.08–92.01) | 1.47 (.18–5.21) |
| Asian | 214 | 0 | 117.36 | 0.00 (.00–31.43) | 0.00 (.00–1.71) | 210 | 1 | 120.18 | 8.32 (.21–46.36) | 0.48 (.01–2.62) |
| Native Hawaiian/Pacific Islander | 8 | 0 | 4.50 | 0.00 (.00–819.50) | 0.00 (.00–36.94) | 8 | 0 | 4.67 | 0.00 (.00–790.16) | 0.00 (.00–36.94) |
| American Indian/Alaskan Native | 27 | 1 | 14.43 | 69.29 (1.75–386.04) | 3.70 (.09–18.97) | 27 | 0 | 15.76 | 0.00 (.00–234.12) | 0.00 (.00–12.77) |
| Hispanic or Latino | 252 | 1 | 137.01 | 7.30 (.18–40.67) | 0.40 (.01–2.19) | 247 | 3 | 141.66 | 21.18 (4.37–61.89) | 1.21 (.25–3.51) |
| Non-Hispanic White | 6776 | 110 | 3644.15 | 30.19 (24.81–36.38) | 1.62 (1.34–1.95) | 6687 | 106 | 3836.86 | 27.63 (22.62–33.41) | 1.59 (1.30–1.91) |
| Unknown | 83 | 0 | 45.92 | 0.00 (.00–80.34) | 0.00 (.00–4.35) | 82 | 0 | 47.10 | 0.00 (.00–78.31) | 0.00 (.00–4.40) |
| HOUSES Index | ||||||||||
| Q1 | 1065 | 13 | 553.04 | 23.51 (12.52–40.20) | 1.22 (.65–2.08) | 1042 | 16 | 567.00 | 28.22 (16.13–45.83) | 1.54 (.88–2.48) |
| Q2 | 1366 | 25 | 711.71 | 35.13 (22.73–51.85) | 1.83 (1.19–2.69) | 1318 | 9 | 731.47 | 12.30 (5.63–23.36) | 0.68 (.31–1.29) |
| Q3 | 2001 | 33 | 1054.35 | 31.30 (21.54–43.96) | 1.65 (1.14–2.31) | 1965 | 33 | 1097.05 | 30.08 (20.71–42.24) | 1.68 (1.16–2.35) |
| Q4 | 3027 | 38 | 1621.91 | 23.43 (16.58–32.16) | 1.26 (.89–1.72) | 3034 | 50 | 1715.48 | 29.15 (21.63–38.43) | 1.65 (1.23–2.17) |
| State | ||||||||||
| MN | 4233 | 77 | 2253.13 | 34.17 (26.97–42.71) | 1.82 (1.44–2.27) | 4161 | 60 | 2375.37 | 25.26 (19.28–32.51) | 1.44 (1.10–1.85) |
| WI | 1069 | 17 | 570.25 | 29.81 (17.37–47.73) | 1.59 (.93–2.53) | 1050 | 12 | 602.32 | 19.92 (10.29–34.80) | 1.14 (.59–1.99) |
| FL | 1173 | 4 | 647.42 | 6.18 (1.68–15.82) | 0.34 (.09–.87) | 1159 | 21 | 662.13 | 31.72 (19.63–48.48) | 1.81 (1.13–2.76) |
| AZ | 1033 | 14 | 568.40 | 24.63 (13.47–41.33) | 1.36 (.74–2.26) | 1023 | 19 | 585.81 | 32.43 (19.53–50.65) | 1.86 (1.12–2.89) |
| Midwest: MN, WI | 5301 | 94 | 2823.38 | 33.29 (26.90–40.74) | 1.77 (1.44–2.17) | 5203 | 72 | 2977.70 | 24.18 (18.92–30.45) | 1.38 (1.08–1.74) |
| Southern: FL, AZ | 2206 | 18 | 1215.82 | 14.80 (8.77–23.40) | 0.82 (.48–1.29) | 2182 | 40 | 1247.94 | 32.05 (22.90–43.65) | 1.83 (1.31–2.49) |
| Rural status census | ||||||||||
| Rural | 897 | 10 | 471.19 | 21.22 (10.18–39.03) | 1.11 (.54–2.04) | 913 | 6 | 515.86 | 11.63 (4.27–25.32) | 0.66 (.24–1.42) |
| Urban | 6621 | 102 | 3555.87 | 28.68 (23.39–34.82) | 1.54 (1.26–1.87) | 6491 | 105 | 3698.93 | 28.39 (23.22–34.36) | 1.62 (1.32–1.95) |
| CCI, age unadjusted | ||||||||||
| 0 | 4674 | 61 | 2457.78 | 24.82 (18.98–31.88) | 1.31 (1.00–1.67) | 4516 | 65 | 2539.67 | 25.59 (19.75–32.62) | 1.44 (1.11–1.83) |
| 1 | 1686 | 28 | 858.35 | 32.62 (21.68–47.15) | 1.66 (1.11–2.39) | 1651 | 25 | 895.17 | 27.93 (18.07–41.23) | 1.51 (.98–2.23) |
| ≥2 | 1397 | 23 | 725.44 | 31.70 (20.10–47.57) | 1.65 (1.05–2.46) | 1471 | 22 | 809.91 | 27.16 (17.02–41.13) | 1.50 (.94–2.26) |
Time points when participants had missing rurality or HOUSES Index were excluded from the rurality- or HOUSES Index–stratified analysis.
Abbreviations: ARI, acute respiratory infection; CCI, Charlson Comorbidity Index; HOUSES Index, housing-based socioeconomic status index; IR, incidence rate; PY, person-years; RSV, respiratory syncytial virus.
aParticipants may contribute to >1 stratum of CCI, HOUSES Index, geographic location, or rurality.
bParticipants with RSV-ARI.
cPerson-years: sum of the follow-up periods at risk expressed in years censored at the first occurrence of the RSV-ARI episode.
dIncidence rate per 1000 person-years: number of first RSV-ARI episodes per 1000 person-years. 95% CI: exact Poisson 95% CI.
eAttack rate: percentage of participants with at least 1 RSV-ARI episode. 95% CI: Clopper-Pearson exact 95% CI.
fStandardized incidence rate: number of first RSV-ARI episodes per 1000 person-years standardized to the age-sex proportions of the 2020 US White population. 95% CI: normal approximation 95% CI.