Pre-requisites for a pandemic
| H5N1 | |
|---|---|
| • New influenza A sub-type: haemagglutinin (H) unrelated to immediate (pre-pandemic) predecessor | ✓ |
| • Little or no pre-existing population immunity | ✓ |
| • Causes significant clinical illness | ✓ |
| • Efficient person-to-person spread | X |