Final answer:
The term 'mortality rate' fits the blank, representing the number of deaths during a given time period within a certain population, usually in relation to a specific disease or epidemic.
Step-by-step explanation:
The blank in the question is to be filled with the term 'mortality rate', which is a measure of the number of deaths in a population during a given time period in general or due to a specific cause. It's calculated based on the expected number of deaths rather than the relatively small number of patients who have contracted a disease. This rate is particularly relevant in discussing infectious diseases such as the HIV epidemic of the 1980s or the recent COVID-19 pandemic, as it quantifies the severity and impact of the disease on a population. The mortality rate often uses age-standardizations to allow for comparisons between different countries and over time, ensuring that differences are accounted for in the structure of the populations being compared.
During the COVID-19 pandemic, for instance, the high mortality rate in the United States sparked intense interest in the variables contributing to the spatial evolution of the pandemic. The outbreak demonstrated how epidemic diseases with low levels of immunity among survivors could lead to higher mortality rates over time since the entire population remains at risk with each recurrence.