When new, virulent diseases emerge, such SARS and Covid-19, the race begins to find new vaccines and treatments for those affected. As the current crisis unfolds, governments are enforcing quarantine and isolation, and public gatherings are being discouraged. Health officials took the same approach 100 years ago, when influenza was spreading around the world. The results were mixed. But records from the 1918 pandemic suggest one technique for dealing with influenza — little-known today — was effective. Some hard-won experience from the greatest pandemic in recorded history could help us in the weeks and months ahead.