Passage: Albert Calmette and Camille Guérin achieved the first genuine success in immunization against tuberculosis in 1906, using attenuated bovine-strain tuberculosis. It was called  bacille Calmette–Guérin (BCG). The BCG vaccine was first used on humans in 1921 in France, but achieved widespread acceptance in the US, Great Britain, and Germany only after World War II.Tuberculosis caused widespread public concern in the 19th and early 20th centuries as the disease became common among the urban poor. In 1815 one in four deaths in England was due to "consumption". By 1918, TB still caused one in six deaths in France. After TB was determined to be contagious, in the 1880s, it was put on a  notifiable-disease list in Britain; campaigns started to stop people from spitting in public places, and the infected poor were "encouraged" to enter sanatoria that resembled prisons (the sanatoria for the middle and upper classes offered excellent care and constant medical attention). Whatever the benefits of the "fresh air" and labor in the sanatoria, even under the best conditions, 50% of those who entered died within five years (c. 1916). When the  Medical Research Council formed in Britain in 1913, it initially focused on tuberculosis research.In Europe, rates of tuberculosis began to rise in the early 1600s to a peak level in the 1800s, when it caused nearly 25% of all deaths. By the 1950s mortality in Europe had decreased about 90%. Improvements in sanitation, vaccination, and other public-health measures began significantly reducing rates of tuberculosis even before the arrival of streptomycin and other antibiotics, although the disease remained a significant threat. In 1946 the development of the antibiotic streptomycin made effective treatment and cure of TB a reality. Prior to the introduction of this medication, the only treatment was surgical intervention, including the "pneumothorax technique", which involved collapsing an infected lung to "rest" it and to allow tuberculous lesions to heal.Because of the emergence of...

Question: Within five years of entering a sanatoria, what percentage of tuberculosis sufferers died?
50%