Here is an October 17, 1918 letter from E.F. Hoban, chancellor of the Archdiocese of Chicago (on behalf of Cardinal, Archbishop George William Mundelein), to the pastors of all the Catholic churches in the archdiocese.
- All evening services are suspended. The faithful may visit the Church during the day for private devotion, but there are to be no public devotions in the afternoons or evenings.
- Wherever missions are being held, they must close with the end of the week, to be resumed, if so desired, after the wave of sickness has passed.
- Masses will take place on Sundays at the usual hours, but no service is to last over 45 minutes. All long sermons are prohibited for the meanwhile, and the clergy will prepare the scheduled Sunday instructions so that it is delivered within five minutes.
- Between the Masses, the church is to be thoroughly ventilated for ten to fifteen minutes, while the people are out of the building, care being taken not to expose the parishioners unnecessarily to cold currents of air.
- Additional ushers will be stationed in the aisles, not only to facilitate both the seating and the exit of the changing congregations, but also to request the departure of any person showing indications of having contracted the disease, by violent sneezing, coughing, etc.
- Church to be cleaned frequently, disinfectant used where necessary, and well-aired at all times.
- During this period, all confirmation and other episcopal ceremonies are suspended, but such churches will receive preference when the epidemic has passed. As the Archbishop has promised the public authorities that every precaution will be taken by the churches under his care during the time of this epidemic, he looks to each of his priests to see that in his own parish this promise is carried out to the letter.
Finally, commend to the prayers of your people, particularly the children, the speedy recovery of all those on whom sickness has laid its hand and the early termination of this epic.
By Order of the Most Rev. Archbishop,