When this city of 8.7 million awoke one year ago to confusing news of a new virus, it sent the world on a wild six-month roller-coaster ride of fear and frantic action.
But after swine flu proved far less lethal than feared, opinion has divided on whether the epidemic was a valuable test-run that left the world better prepared to handle a more lethal avian flu pandemic, or an episode that left the public jaded and weary.
Mexicans are bristling after following initial government recommendations that may have been counterproductive, and question the value of late-arriving vaccines.
But the director of Mexico's National Center for Epidemiology and Disease Control insists the nation — and the world — are better prepared for another, more deadly flu outbreak.
"We as a global community have been very lucky to have this opportunity to do this massive test, practice-run, with a virus," Miguel Angel Lezana said.
He says a deadly flu is coming sooner or later: "We have to be prepared for it."
Within five days of last year's April 23 flu announcement, Mexico City would essentially shut down, streets empty of traffic and almost every business shuttered by government order. Only a few wary, masked silhouettes plied the streets, and a pall of fear and mistrust settled over the city.
One year later, the fear is gone but Mexico still is feeling the human and economic consequences of swine flu.
Nearly 18,000 died around the globe
The pandemic killed 1,185 people in Mexico — out of 17,700 deaths worldwide. Tourism revenues, Mexico's largest source of income after oil and remittances, have yet to recover to pre-flu levels.
Lezana estimates that about half of Mexico's 107 million people have immunity to the virus, either through the vaccine or contracting a mild case of swine flu, giving the country a "herd immunity" that would slow the transmission chain of the H1N1 virus.
But Mexico, like many other nations, is still struggling to give out increasingly unpopular vaccines. About three-quarters of the way to fulfilling the nation's goal of 30 million vaccinations, many here wonder why they should risk the shot's real or imagined side effects at this point.
Carla Gonzalez, a 25 year-old homemaker, says she feels misled by the whole government response.
A flu vaccine, she says, made her sick. And she wonders if the whole emergency wasn't concocted to get people's minds off Mexico's economic and social problems, echoing accusations — mainly from the political left — that the crisis was overblown.
"I won't ever get vaccinated again," Gonzalez said. "We still don't know if this was something real, or something that the authorities manipulated, a deception."
The World Health Organization estimates only 1 in 10,000 people have significant reactions to the vaccine.
Mexico struggled to get enough vaccine
The swine flu outbreak persuaded Mexico to develop the capacity to make its own flu vaccines after it had trouble buying enough.
Mexico has slowly acquired the vaccine — even as other nations sell or destroying stocks — to vaccinate about 23 million people so far, even setting up inoculation stands in the Mexico City subway.
One lesson of the epidemic is that information, true or not, flows more quickly on the Internet than through official channels.
Mexico City Health Secretary Dr. Armando Ahued acknowledges that the city's vaccination program was affected "by rumors that began to appear on the Internet that the vaccine was bad ... and that sparked a huge fear in the public."
Another unfortunate lesson: Publicly reporting the swine flu outbreak, and energetically pursuing measures to contain it, wound up costing Mexico about 0.3 percent of its $1 trillion GDP, largely in lost tourism income. Tourism has since started to recover, but Mexican officials say some sort of international fund to compensate countries for early reporting of new outbreaks is needed.
If not, "the next time, countries are going to say, 'no, this is going to affect our economy, it's better not to say anything,'" Ahued said.
Recalling the first days of the epidemic when hospitals were filling up with people on respirators, he said the public-health message — avoid infection, and seek treatment early — has percolated into the general population.
It often shows in small ways.
"Now, when you go to a restaurant or some other public place, almost all of them are giving out gel. When the waiter assigns you your table, they offer gel, or there is a bottle of gel at the door," Ahued notes. "There is an improvement in culture and education."
Franciso Santos, 28, followed the government's instructions but now feels deceived. He wore a disposable surgical mask to work as a systems engineer every day at the height of the outbreak, but such masks have since been found to be useless in protecting uninfected people, and may even expose them to greater risk.
Guadalupe Soto Estrada, an epidemiologist at the National University's Department of Public Health, explained that using disposable masks "is sometimes worse, because people take them off and on and touch them, so it is likely the micro-organisms on the mask will be passed onto whatever surface they come in contact with."
Authorities now only recommend masks for infected people, who should probably avoid going out in public anyway.
"I hope next time they (authorities) act with more information and more caution," Santos said. "They alarmed people. ... There was a lot of economic and psychological damage."
Ultimately, Mexico, like most countries, probably will never be able to build enough hospitals to deal with a highly lethal and contagious flu. But in 2009, authorities discovered the answer was to stop people from flooding into hospitals — and potentially collapsing the health care system — by instructing primary-care physicians to give anti-viral medication to anyone who showed multiple flu symptoms, even before any tests were run on them.
The World Health Organization says the virus has now spread to 213 countries, virtually every corner of the globe — proving the disease could not be contained even by banning flights or product imports from Mexico, or quarantining travelers who had passed through here, something several countries did early in the 2009 pandemic. The disease spread anyway.
"This is something we really do not want to see done the next time there is this type of pandemic," Lezana says.