| since the epidemic outbreak | 2 | temporal |
| discovery → lead to → vaccine | 5 |
| discovery → lead to → the development of a vaccine | 3 |
| discovery → be → vaccine | 3 |
| negative | neutral | positive |
| 0.122 | 0.495 | 0.382 |
| Raw frequency | 11 |
| Normalized frequency | 0.234 |
| Modifier score | 0.500 |
| Perplexity | 307.950 |