But are residents of country X more likely to contract the more contagious forms of disease P? In any case, degree of contagiousness doesn’t indicate the deadliness of a disease. It indicates instead the likelihood of spreading to others.

The statistic in the stimulus concerns residents of country X. So, deaths from people who don’t reside in country X are irrelevant, because they aren’t counted in the statistic.

This could explain both the lower rate of disease P in country X (mild cases go unreported) as well as the higher likelihood of death for those reported to have disease P. The reported cases would be more severe, on average, than cases in other countries.

Varying levels of disease P from year to year doesn’t help explain a lower rate of the disease in country X or why the reported cases are more deadly. We would already expect the number of cases not to be exactly the same every year.

We’re trying to explain the higher fatality rate of disease P in country X. Other illnesses don’t affect the fatality rate of disease P.