A new vaccine was tested in a trial. 5000 people were given the vaccine and 5000 people were given a placebo (an injection with no vaccine). The number of people who caught the disease during the trial is shown in the table.
| Group | Number of people | Number who caught the disease |
|---|---|---|
| Vaccine | 5000 | 25 |
| Placebo | 5000 | 200 |
Calculate how many times more likely a person in the placebo group was to catch the disease than a person in the vaccine group.
[2]
Evaluate whether these data show that the vaccine is effective.
[4]