Volume 17, Number 2—February 2011
Dispatch
Comparison of Pandemic (H1N1) 2009 and Seasonal Influenza Viral Loads, Singapore
Table 1
Comparison of baseline characteristics between patients with pandemic (H1N1) 2009 and seasonal influenza H3 infection, Singapore, May–November 2009
| Characteristic | Pandemic (H1N1) 2009, no. (%), n = 578 | Seasonal influenza H3, no. (%), n = 77 | p value |
|---|---|---|---|
| Age, y | <0.0001 | ||
| 0–4 | 69 (11.9) | 7 (9.1) | |
| 5–14 | 144 (24.9) | 11 (14.3) | |
| 15–34 | 250 (43.3) | 28 (36.4) | |
| 35–54 | 72 (12.5) | 13 (16.9) | |
| >55 |
43 (7.4) |
18 (23.4) |
|
| Female sex |
275 (47.6) |
41 (53.2) |
0.3959 |
| Comorbidities* | 262 (45.3) | 22 (28.6) | 0.0068 |
| Asthma | 120 (20.8) | 7 (9.1) | 0.0137 |
| Chronic lung disease | 15 (2.6) | 3 (3.9) | 0.4584 |
| Cardiac disease | 21 (3.6) | 4 (5.2) | 0.5214 |
| Chronic renal failure | 21 (3.6) | 2 (2.6) | 1.0000 |
| Chronic liver disease | 11 (1.9) | 0 | 0.6275 |
| Cerebrovascular disease | 9 (1.6) | 2 (2.6) | 0.3776 |
| Neoplasms | 22 (3.8) | 3 (3.9) | 1.0000 |
| Diabetes | 41 (7.1) | 5 (6.5) | 1.0000 |
| Pregnancy | 39 (6.7) | 2 (2.6) | 0.2115 |
| Immunocompromised | 27 (4.7) | 2 (2.6) | 0.5621 |
| Receipt of steroid medication | 23 (4.0) | 1 (1.3) | 0.3429 |
| Autoimmune disease | 14 (2.4) | 1 (1.3) | 1.0000 |
| Neurocognitive disease | 12 (2.1) | 1 (1.3) | 1.0000 |
| Neuromuscular disease |
2 (0.3) |
0 |
1.0000 |
| Premitigation phase |
104 (18.0) |
51 (66.2) |
<0.0001 |
| Clinical severity† | 0.0462 | ||
| Severe cases‡ | 23 (4.9) | 1 (3.8) | |
| Hospitalized cases§ | 222 (46.8) | 6 (23.1) | |
| Outpatient only | 229 (48.3) | 19 (73.1) |
*Patient had >1 of the conditions listed.
†Analysis was limited to patients in whom influenza were diagnosed during the mitigation phase (n = 474 for pandemic and n = 26 for H3 seasonal influenzas). Singapore switched from premitigation (i.e., containment) to mitigation management protocols on July 8, 2009, which altered how patient treatment with oseltamivir was initiated. However, this transition does not affect the results shown above because none of the patients were undergoing treatment when these first diagnostic samples were taken.
‡Patients requiring intensive or high-dependency care or who died.
§Patients requiring hospitalization because of clinical conditions but not intensive or high-dependency care.