TABLE 2. Counterfactual analysis of the impact of mass vaccination and active case-finding interventions on the chance of a large measles outbreak and median duration of a measles outbreak among shelter residents — Chicago, Illinois, 2024.
| Intervention start dates |
Chance of additional measles cases among shelter residents,* % |
Duration |
|||||
|---|---|---|---|---|---|---|---|
| Mass vaccination | Active case-finding | Zero cases | 1–9 cases | 10–49 cases | 50–99 cases | ≥100 cases | Last rash onset in outbreak (median) |
| Never |
Never |
24 |
7 |
— |
— |
69 |
May 26 |
| Mar 15 |
Never |
24 |
10 |
23 |
28 |
15 |
Apr 21 |
| Mar 8 |
23 |
13 |
28 |
27 |
8 |
Apr 17 |
|
| Mar 8 |
Never |
24 |
15 |
40 |
21 |
1 |
Apr 14 |
| Mar 8 |
23 |
17 |
43 |
17 |
1 |
Apr 9 |
|
| Mar 1 | Never |
24 |
24 |
49 |
3 |
— |
Apr 3 |
| Mar 8 | 23 | 26 | 49 | 2 | — | Mar 30 | |
* Number of measles cases beyond the index case.