Among the worst moments of the 1918 influenza pandemic were Philadelphia's overwhelmed morgue stacking unembalmed bodies without ice on multiple floors until storage was found, or the city resorting to steam shovels for digging mass graves.

The 1918 Spanish influenza – a vicious disease, some historians call it – emerged as World War I was ending.

The virus of a century ago infected approximately 500 million people, or one-third of the world’s population, according to the Centers for Disease Control and Prevention.

The East Coast and Philadelphia "were hit at a much earlier stage of the pandemic," says David McKinsey, an infectious disease physician at the Research Medical Center in Kansas City, Missouri.

As the coronavirus escalates around the globe, researchers are reexamining the 1918 pandemic, how it spread and how people responded.

States and cities devised their own strategies because "the federal government really didn't do a lot," McKinsey says.

The 1918 influenza did not come from Spain.

It came in three waves, "the first in the spring of 1918; the second, more deadly, in the fall of 1918; and the third in February-March in 1919," Navarro says.

The war and massive troop movements spread the virus to all points of the globe.

8, 1918, the day before 300 sailors from the city arrived in Philadelphia.

Health officials, who either believed it was true or wanted to avoid hurting public morale, said there was little chance it would spread among the public.

In 1918, Philadelphia was the third-largest city in the USA.

Parade spread virus like wildfire.

Like today's coronavirus, the 1918 virus spread primarily by person-to-person contact.

"That parade gave the epidemic a shot of adrenaline," Navarro says.

Several physicians urged Wilmer Krusen, the city's public health director, to cancel the parade.

28 parade started at Diamond Street, moved south on Broad and ended at Mifflin Street, according to the Evening Public Ledger, a city newspaper.

Max Starkloff," Navarro says.

The city's health commissioner "immediately started warning the public and told physicians to report influenza cases.".

Starkloff, fully supported by the city's mayor, "was very quick to implement city closures," Navarro says.

He closed public places such as schools, theaters, playgrounds, city courts and churches and banned gatherings of more than 20 people.

"They recognized that crowds were a danger," McKinsey says.

"They were upset because they were losing revenue," McKinsey says.

Though "Starkloff listened to business pleas to reopen, he didn't reopen the city all at once," Navarro said.

Post-pandemic analyses revealed "social distancing was highly effective against virus transmission," McKinsey says.

In the pandemic's aftermath, "we see a change in efforts for better public health," says Deanne Stephens, professor of history at the University of Southern Mississippi.