"In San Francisco, you couldn't go out in the street without a mask," said Alfred W. Crosby, historian and author of "America's Forgotten Pandemic: The Influenza of 1918."
"The important thing is the measures that were taken were ineffective and taken too late," Crosby said.
Still, some tried to continue with life as if the pandemic didn't exist. In Philadelphia, a mass rally was organized to sell war bonds, despite the concerns of some city officials.
The rally, attracting a crowd estimated at 200,000, proved a fertile ground for the virus. In that hard-hit city, some 12,000 deaths from "the Spanish Lady" were reported.
Medical facilities were strained beyond the breaking point as many doctors and nurses were serving overseas. Schools, businesses, farms and factories were shuttered as workers and customers were afraid to leave the house – or were dead.
The military fighting in Europe was also decimated by the virus. In many units, the flu killed more men than the enemy.
In the absence of any cure or treatment, paranoia, nationalism and suspicion ran rampant. "In 1918, people tried to blame it on the German U-boats who came up to the coast and gave everyone the flu," said Crosby.
The Spaniards called it the French flu. The name Spanish flu likely came from the fact that Spanish newspapers – uncensored by authorities because Spain did not participate in WWI – were among the first to report large numbers of deaths from the disease.
Without a cure, the desperate reached for a number of remedies. Some hung balls of camphor around their necks. Others ate lumps of sugar flavored with kerosene.
"People did everything you could think of," said Crosby. His favorite cure of the time: "Tie a red ribbon around your right arm."
Though smaller waves of the Spanish flu came and went after 1918, the disease left almost as quickly as it arrived – anyone exposed to the illness had either developed a resistance or died.
Health officials worldwide have expressed alarm at the vigor of the avian flu, and doctors debate whether society is better equipped to deal with a pandemic than in 1918.
"We're in a much better position now than we were then," said Dr. Stephen Baum, Chairman of the Department of Medicine and infectious disease specialist at Beth Israel Medical Center in New York City.
"There are some antiviral agents that can probably have a beneficial effect on ameliorating the disease [avian flu] a bit and decreasing transmission," Baum said. Both oseltamivir (Tamiflu) and zanamivir (Relenza) have been shown to be effective against influenza.
"These things can be identified in remarkably short time these days," Baum added, noting that the SARS virus was identified in less than six weeks, whereas it took nine to 12 months for the cause of Legionnaire's disease to be identified after it appeared in 1976.
Baum also notes that the role of hand washing and personal hygiene is better understood today than in 1918.
"We've obviously come a long way," Baum said. "It doesn't have to happen again."
But doctors also admit that much work remains to prevent another deadly pandemic.