For its part, Allentown adopted a nuisance code in 1867 that restricted the keeping and disposal of livestock while it curtailed operations like bone and fat rendering plants. After a twenty-five year pause, during which Allentown made few improvements in terms of public health and health care, and left patients in the hands of private practice doctors and the city's women, it created a Board of Health to enforce nuisance codes and quarantine the sick. These efforts were capped in 1899 by the decision to build a community hospital and nursing school with massive aid from the city's women. Though Allentown Hospital was not, from a standpoint of personnel, as well appointed as St. Luke's, it was the first organization to gather medical staff and expensive new equipment under one roof and was a much better proposition than carting the city's sickest citizens to Bethlehem. The area's hospitals performed complicated medical procedures while its citizens used outdoor toilets and drank water fouled by those toilets, but it was this infrastructure that would have to hold the line against the greatest health threat in modern times.
The conflagration known as World War I had a profound impact in the Lehigh Valley as several firms were deeply involved in the war effort. Bethlehem Steel, far and away the most important of these firms, produced as many tons of finished war goods as did some of the major combatants. While the war effort ground on, an influenza virus began to mutate somewhere in the world. By August of 1918, what would come ot be known as the influenza epidemic of 1918-1919 burst from Africa and Western Europe, followed a week later by an explosive outbreak in Boston, Massachusetts. New England was left with tens of thousands dead and leaders in Allentown and Bethlehem watched the situation with dread.
The long Indian summer the valley sweltered through eased a bit in late September. The first cases of influenza were detected among steelworkers on September 28. Bethlehem Steel's house doctor personally surveyed the situation in Boston and began to raise the alarm in Bethlehem, as he believed that a true epidemic was imminent. September 27 saw an additional eight steelworkers stricken and the following day Allentown and Bethlehem announced their intention to meet and work closely together to combat the flu. In reality, both cities would largely see themselves through the epidemic without assistance from the other. On September 30, an emergency hospital had been opened in a National Guard armory in Bethlehem while representatives from the U.S. Public Health Service and the state's medical inspector declared that Bethlehem was equipped like no other city in the country to handle the numbers of cases sure to follow. Even so, with twenty-five sick men at the steel plant by October 1, the federal government was becoming convinced a quarantine of at least Bethlehem Steel was necessary. The Army Ordinance Department did not want to contemplate the effect the plant's closure would have on the allied war effort and pushed local and state officials to act to prevent such a calamity. On October 4 a statewide quarantine was issued, but in Bethlehem it was backed by federal force. Sick steelworkers who had families could be cared for at home while single men would be moved immediately to St. Luke's. No one not connected with the firm would be allowed on the property and men were rigorously screened for any symptoms and sent immediately to the firm's small dispensary for observation. All private physicians in the city had to report cases of the flu and heads of households were threatened with jail for failure to report sick family members. Milkmen were ordered to report any bottles still sitting on steps from the day before as a sort of ad hoc attempt to prevent the deaths of entire families from neglect as other cities would witness.