Table 3.
Posterior summaries of severity of 2009 pandemic A/H1N1 influenza in England. Values are posterior median estimates (95% credible intervals) for all ages
| Parameter | Wave of influenza | |
|---|---|---|
| June–August | September–February | |
| Symptomatic case severity ratio (%): | ||
| Hospitalisation (sCHR) | 0.54 (0.33 to 0.82) | 0.55 (0.28 to 0.89) |
| Intensive care admission (sCIR) | 0.05 (0.03 to 0.08) | 0.10 (0.05 to 0.16) |
| Fatality (sCFR) | 0.015 (0.010 to 0.022) | 0.025 (0.013 to 0.040) |
| Infection severity ratio (%): | ||
| Hospitalisation (CHR) | 0.19 (0.12 to 0.29) | 0.19 (0.10 to 0.32) |
| Intensive care admission (CIR) | 0.02 (0.01 to 0.03) | 0.03 (0.02 to 0.06) |
| Fatality (CFR) | 0.005 (0.004 to 0.008) | 0.009 (0.004 to 0.014) |
| Numbers infected, by severity*: | ||
| Total (NInf) | 1 750 000 (1 235 000 to 2 470 000) | 3 909 000 (2 316 000 to 8 223 000) |
| Symptomatic (NS) | 606 100 (419 300 to 886 300) | 1 352 000 (829 900 to 2 806 000) |
| Hospitalisation (NH) | 3 200 (2 300 to 4 700) | 7 500 (5 900 to 9 700) |
| Intensive care admission (NI) | 310 (200 to 480) | 1 340 (1 030 to 1 790) |
| Fatality (ND) | 90 (80 to 110) | 340 (310 to 380) |
| Attack rates (%): | ||
| Infection (IAR) | 3.4 (2.4 to 4.8) | 7.7 (4.6 to 15.0) |
| Symptomatic (SAR) | 1.2 (0.8 to 1.7) | 2.7 (1.7 to 5.3) |
| Proportion of infections that are symptomatic (cS|Inf) (%) | 35 (26 to 45) | 35 (26 to 45) |
| Detection probability (%): | ||
| Symptomatic (dS) | 40 (24 to 59) | 36 (19 to 57) |
| Hospitalisation (dH) | 30 (20 to 43) | 20 (15 to 25) |
| Fatality (dD) | 88 (78 to 95) | 90 (80 to 96) |
*Numbers rounded to the nearest 100 for infections, symptomatic infections, and hospitalisations, and to the nearest 10 for intensive care admissions and deaths.
See table 2 for list of abbreviations and meanings.