JIM LEHRER: And now to a report from Mexico City by Ray Suarez, who has been on the story in Mexico for the past few days.
RAY SUAREZ: For the first time since the outbreak began in Mexico, more flu sufferers are leaving the hospital cured than are coming through the doors sick and needing treatment.
At the National Institute for Respiratory Diseases, ground zero for sick patients from across the county, doctors like Jose Luis Sandoval Gutierrez are beginning to feel the worst of the H1N1 epidemic is over.
DR. JOSE LUIS SANDOVAL GUTIERREZ, National Institute for Respiratory Diseases: For me, this crisis, epidemiology crisis is going down. It's controlled now.
RAY SUAREZ: Mexico and the world caught a break as this new strain emerged: A common antiviral flu treatment, Tamiflu, is effective against the disease. Several days of treatment with the drug, or another called Relenza, and most patients are on their way home.
DR. JOSE LUIS SANDOVAL GUTIERREZ: The response has been good, very good.
RAY SUAREZ: Laboratories around the world have been helping to screen Mexican samples, since the country's labs are overwhelmed by the demand. The number of confirmed cases of swine flu in Mexico crept up over the weekend, as testing answered questions, but mysteries remain.
Fernando Flores, a street sweeper, did his morning's work in the Condesa neighborhood of Mexico City with a broken heart. His son, Roberto -- in his late 20s, robust, no health problems, four children -- died in the early days of the epidemic before doctors had identified the new strain. His death certificate says pneumonia.
FERNANDO FLORES (through translator): They did not really know what's going on with him. They were inventing medicines they were giving him. By the time they figured out what he had, my son was dead.
RAY SUAREZ: Across from a popular weekend market in the city's historic center, health workers at a mobile medical station are answering questions and screening patients for the new H1N1 virus, hundreds of patients.
This capital city has more cases of H1N1 than any other city on Earth. Worried people can find out in a matter of minutes whether they've got the virus that's made hundreds sick.
NURSE (through translator): If they have any symptoms, we have a doctor here, and they can take a tests and get results in 10 to 12 minutes. If they test positive, we give them medicine and send them to the nearest hospital.
RAY SUAREZ: Clinics and hospitals are still screening large numbers, but only a small minority are testing positive for the flu. Still, masks, hand sanitizer, and empty streets, for the moment, have become the new normal. H1N1 can be suppressed, but never wiped out.
PABLO KURI, epidemiologist: This strain has arrived to the world to be here forever.
RAY SUAREZ: Pablo Kuri is an epidemiologist advising Mexico's secretary of health. He said his country and the world have learned from recent public health threats that came from the respiratory virus SARS and the biological attacks made with anthrax.
PABLO KURI: We are better prepared now than we were before SARS, for example, because SARS taught us lessons that we should have, and before anthrax, because anthrax taught us lessons, and before T.B., and before malaria, and before tuberculosis. You're always learning. And the system is always better prepared when you accumulate experience.
RAY SUAREZ: National health systems around the world now share information and coordinate their responses to new infections. Once the new flu strain was identified, local and national governments tried to limit the spread by limiting human contact.
They tried to force Mexicans to take a break from each other. Restaurants could only serve takeout food; businesses were urged to close to bridge two national holidays, Labor Day on May 1st and Cinco de Mayo, May 5th. And the country immediately mounted a full-scale public information campaign, urging people to keep their distance and wash, wash, wash.
For people with resources, it seemed to work well. But what if you can't wash, because there's no water?
"Thank God the children around here are well," Estela Galvan said. In her barrio, a cluster of tiny houses built by the residents on an old railroad right of way, with no infrastructure, they can fill water jugs and cisterns only on the three days or so per week there's enough pressure in their water pipes.
ESTELA GALVAN (through translator): We don't have any water. We have to carry it in. And now we really need water because of the virus that's all around us.
RAY SUAREZ: The head of the local civic association explained that you manage, you cope when water service is sporadic, season in and season out, with no hope, no promise of better service from the government.
But now, with the big message being that, in order to fight the swine flu, you've got to wash yourself and everything you use more often, having no water is not just inconvenient. It's frightening.
The virus has not been discriminating in its choice of targets. It's hit men and women roughly equally, the humble and the well-connected.
MANUEL CAMACHO SOLIS, former mayor, Mexico City: I had a very high fever, and it wouldn't go away.
RAY SUAREZ: One of the earliest cases of H1N1 was a former cabinet secretary and mayor of Mexico City. Manuel Camacho Solis had just come from a business lunch and felt terrible.
MANUEL CAMACHO SOLIS: I couldn't eat anything. My body was kind of with all kinds of aches, but I didn't think I was really in a dangerous situation. I just wanted to feel better.
RAY SUAREZ: Rest and antibiotics didn't help. He went into the hospital as the president of Mexico was closing the country's schools. Camacho had led his city through the terrible earthquake of 1985 and an air pollution crisis. He thinks the response has been good.
MANUEL CAMACHO SOLIS: It's a simple balance. It's the health of the people or the economy. And in a case like this, the health is more important. So they're extreme measures, but if you can save some lives, it's worth it.
RAY SUAREZ: One of the former mayor's doctors was Francisco Moreno. We met after he worked a long string of 19- and 20-hour days.
DR. FRANCISCO MORENO: We're going to see an increase in the number of cases; that's for sure. But we're going to see a decrease in the number of dead people.
RAY SUAREZ: It's a dramatic turnaround since two weeks ago, when the death rate from early cases was alarming to Dr. Moreno and his colleagues, who were on the front line.
DR. FRANCISCO MORENO: We were very afraid, because you had young people dying from influenza. That was something that make us -- we were thinking that there was something else going on.
RAY SUAREZ: Dr. Moreno has concluded the reason the deaths were heavily concentrated among Mexicans 20 to 50 years old is that these are the people most concentrated in the workforce, most likely to come in contact with large numbers of people, and most likely to do what many Mexicans do when they get sick, wait.
DR. FRANCISCO MORENO: In Mexico, it's a culturalÂ thing not to go to the doctor. You can even buy medications at the drug store without prescription. So many patients take drugs by themselves. They don't ask the doctor. So they were coming very late to the hospital.
RAY SUAREZ: Understanding that habit could be deadly, the government ran radio ads asking people not to self-medicate and not to wait to see a doctor.
PABLO KURI: The days between people getting sick and getting to the hospital cut down from eight days to two or three days, and they get the treatment. And, of course, we diminished the possibility of complications or even death.
MANUEL CAMACHO SOLIS: It's a complex mix of social, political communications, scientific, and especially looking at the part that is suffering.
RAY SUAREZ: It will take a while to figure out whether the results in health and well-being matched the serious economic hit the country took from the widespread shutdowns.
Meanwhile, city residents awkwardly wrestled with how not to gather and socialize over the long holiday weekend. Even prayer was considered something better done in solitude.
The basilica and shrine of the Virgin of Guadeloupe, like other Mexican churches, closed its pews to regular masses, urging the faithful to watch on national television instead.
But the basilica is no ordinary neighborhood church. And while crowds were still way down, hundreds still made their way here, some for a blessing from Mexico's patron saint in the midst of an epidemic.
For some, faith overcame public health warnings. Running fingers over a framed image of the Virgin of Guadeloupe with a bare hand, then touching those fingers to your own face brought risk and comfort.