Answer:
Old, sickly people and young laborers are useless to the nation because they cannot be productive citizens.
Step-by-step explanation:
This is the idea that Swift satirizes in this passage. He tells us that the rich, productive people of the country are worried about the fate of the old, the sick and the poor. However, they are worried because they consider them a burden. He asks us not to worry, as the old, the sick and the poor are constantly dying off because of vermin, famine and filth. This means that the problem solves itself, and we do not need to worry. He is mocking the fact that these people are considered "useless" because they cannot be productive citizens.