What Foretells A Pandemic?

What the alert level doesn't tell us is, what will end up happening? How serious will it turn out to be?

"If we had a dozen experts in public health and infectious disease, or 20 in this room, it would be hard to find two of them that actually agree on an answer to this very important question of how bad is it going to get?' Dr. Redlener said. "Will we see a 1918 redux?"

1918 is the benchmark for bad. The 1918 flu killed fifty million people or more.

In World War I, more soldiers died of the flu than on the battlefield. Living in close quarters, they got the sniffles one day and were often dead the next.

(AP (file))

In 1998 a molecular biologist, Dr. Jeffrey Taubenberger, announced he had decoded the 1918 virus and mapped its genome, which meant lessons could be learned about why it was so deadly, with applications for other flus.

At the time, Dr. Taubenberger worked at the Armed Forces Institute of Pathology in Washington.

There, he had access to an incredible warehouse filled with tissue samples - millions of them - from dead soldiers dating all the way back to the Civil War, including, he discovered, soldiers from WWI who died of the 1918 flu virus.

"What we're doing is analyzing a virus right out of the lungs of people who died in the prime of their lives, soldiers who were just in their 20s when they died," he said.

Taubenberger showed us what a typical sample from a 1918 flu victim looks like.

Since then, microbiologists have been able to compare the genetic signature of the 1918 flu with newer viruses.

Which is how the week ended with the Centers for Disease Control announcing the first good news about H1N1.

"We do not see the markers for virulence that were seen in the 1918 virus," Nancy Cox of the CDC said.

Is this a pandemic non-event? No one knows.

"Even if it turns out that H1N1 is relatively mild on the front end, it could come back in more virulent form during flu season," President Obama said.

That's exactly what happened in 1918. Viruses mutate, unpredictably.

"This is too much of a gamble over public health to say, let's see if it really becomes severe," said Dr. Marie-Paule Kieny, director of the WHO's Initiative for Vaccine Research.

So, are the warnings, the school closings, the masks, the stockpiles of Tamiflu just overkill? Media hype.or not, what if the H1N1 virus does have an even more vicious second act?

Tucked inside their home near the city center, Tracey Bryan and her husband Valdir Ugalde are trying to keep their daughters entertained.

"Movie theatres are closed, all public events and activities have been closed for large groups of people, so those aren't really options," Tracey said. "We're just trying to be cautious, but not scared."

They worry, of course, about 2-month-old Alexandra and Sophia, nearly 3. But Tracey, originally from North Carolina, says it doesn't feel as dangerous here as the rest of the world might think.

"My mom of course would say, 'Come home tomorrow,'" Tracey said.

With everything from restaurants to sporting events shut down until at least Wednesday, one joke heard in Mexico City is that more people will die from boredom than the flu.

With nowhere else to go, John Marrone from the American School in Mexico City is teaching history in the park.

"We can't go to school, it's absolutely forbidden that we go to school," Marrone said. "I was told by my superiors not to take them to school, it's against the law."

About the only place people do gather these days is at hospitals. Few of those waiting at Mexico City's general hospital are here for the flu; most have come for other health reasons, creating a constant crowd at the main gate.

Come inside the walls of this big metropolitan hospital and it becomes like a refuge, almost like a garden.

But head toward the influenza ward and they want you to have on the mask and the rubber gloves.

Down a long outdoor walkway, Dr. Jorge Ramirez guided us toward the infectious diseases unit, which he says is not as busy as it was a week ago.

"You were never overwhelmed here?" Blackstone asked.

"No, no. Never," Dr. Ramirez said.

Only seven swine flu patients remain in the isolation ward here; six are due to be discharged shortly.

Hernando Flores is here to visit his 28-year-old daughter Paulina now recovering well. "Sunday, she feel very bad," he said.

"So how many days was she in the hospital before she said, 'I feel wonderful'?" Blackstone asked.

"Six."

With early diagnosis and treatment, Dr. Ramirez says they now know the virus can usually be beaten.

We don't know for sure what's going to happen," he said, "but we think - think - we're getting better."

The Mexico City district of Gustavo Madero, where poverty and a chronic water shortage makes hygiene difficult, has more victims of the virus than anywhere else. The basilica here attracts pilgrims from all over, perhaps a factor in spreading the virus.

Now in the middle of a five-day shutdown of all but essential business, Mexico is hoping to stop the virus' spread. But the shutdown is costing Mexico City alone some $57 million a day.

Valdir Ugalde said the stores' closing and the economic ramifications caused by the virus are a bigger concern than the flu itself.

In her 11 years in Mexico his wife Tracey Bryan says she has experienced plenty of hardships large and small.

"You learn to adapt, and the people of Mexico do that very well," she said.

Having adapted to a life behind masks, Mexicans are waiting to be assured they can once again breathe easily.