Same urban setting, same flu virus -- but life couldn't be more different for residents of Mexico City and New York.
The two massive conurbations are the leading centers for the global swine flu outbreak.
But where the flu is believed to have killed 84 people in Mexico, most of them in the capital, New Yorkers appear to be escaping with nothing worse than mild coughing and fever.
Mexicans have resorted en masse to wearing germ-shielding face masks and city authorities have ordered bars, restaurants, gyms and other gathering places shut.
But in the Big Apple, life continues undisturbed with nearly all schools functioning, restaurants packed, and big crowds attending Yankees and Mets baseball games.
"The irony of it is that the flu doesn't seem to be affecting Americans the same way it does in Mexico," New York State Governor David Paterson said.
The death of a Mexican toddler in Texas on Wednesday raised the fear factor in the United States.
Both Texas and California have declared a state of emergency, while Department of Homeland Security chief Janet Napolitano says the country is ready to face a "full-fledged pandemic."
However, early evidence does suggest that the flu bug has less potency north of the Mexican border.
Only five people nationwide have been hospitalized. And even the boy who died in Texas was "highly likely" to have been infected in Mexico, rather than the United States, according to Texas officials.
New York health officials say hundreds of people may have been infected in the city -- nearly all at a single school in the Queens neighborhood -- and that 51 cases are confirmed.
Only two people have been hospitalized -- an infant boy and a woman -- and on Wednesday they were declared to be home and making a good recovery.
"Up till now in New York City, this virus is acting the same way as seasonal flu," New York Health Commissioner Thomas Frieden said.
Paterson delivered a similarly reassuring message.
"We do not see a cause for alarm at this time," he said. "We are preparing ourselves for the worst case scenario, but at the same time we have not identified anyone who was healthy who has become critically ill as a result of this virus."
Why there should be such a difference between New York and Mexico remains a mystery.
Paterson pointed to disparities between general health levels in the two countries.
"There are high levels of carbon, high levels of dioxins in many cities in Mexico, very difficult conditions," he said.
"It does not seem to be having the impact, so far, on Americans as it does on people in the Mexico region at that time."
US officials are warning that more deaths are likely, although there is no suggestion of a toll remotely approaching that from regular flu -- more than 35,000 fatalities a year.
As in normal flu, those most at risk will be "people with underlying risk factors -- such as young children, the elderly, and people with chronic medical conditions," the New York health department said.