What arguments and evidence does he provide to show that it was the effectiveness of the public health movement, not antibiotics, is the reason for declining mortality rates in the 19th century?

According to Porter, public health initiatives were stimulated in the 19th century by epidemics of cholera and yellow fever, and war. What arguments and evidence does he provide to show that it was the effectiveness of the public health movement, not antibiotics, is the reason for declining mortality rates in the 19th century?

Roy Porter, The Greatest Benefit to Mankind, pages 397-492 (text attached)

Between 400-500 words