Blake sees "every Infant's cry of fear" and is disgusted by it (line 6). The way that he expresses the suffering of these children is with his repeated use of the word "cry", as in: "the Chimney-sweeper's cry" (line 9). These chimney sweepers were also children. They had to climb into blackened chimneys and clean them out, again, for a very low wage. Most of them became very sick because of all of the coal dust, if they were not already afflicted by the plague. The work of the sweepers, as described by Blake, literally "appalls" the churches and makes them white. The fact that the children of London are in misery and poverty makes the upper class, the church and the monarchy even richer. The children who cry out for salvation portray the impoverished London that Blake sees.
London is a miserable city in Blake's time, as seen by the "youthful Harlot's curse" (line 14). If the young women of London were not working in the factories, it is very possible that they were supporting themselves by prostitution. These girls had no choice but to sell themselves in order to stay alive. Most likely, these girls were abandoned by their families because of poverty, death or both. If not, the girls themselves abandoned their families because of alcohol. At this time, the production of gin was rampant. Gin was very inexpensive to buy and even less expensive to make. Many people would leave their homes and families, choosing gin instead of responsibility. This is one of the many reasons why children were orphaned. Prostitutes were infected by plague, just as the children were, and they were very poor. When they became pregnant, they had no way to take care of their children. Their "curse" that Blake describes is this. They "Blast[ed] the new-born Infant's tear, And blight[ed] with plagues the Marriage hearse" (line 15-16). The prostitutes blasted and cursed the cries of the children that they could not support or help, and the way that marriage was thought of by them was related to their death.