Late last year, what is thought to be a bat-associated coronavirus infected humans in Wuhan, a city of 11 million in China, possibly after a stopover in illegally traded pangolins—setting off a global pandemic. This kind of thing has happened before—with AIDS, SARS, and MERS, for example. Much remains unknown about the biology of COVID-19, which is alarmingly communicable by people with few or no symptoms. But an epidemic is only part biology. It is also driven by cultural factors, and urbanization is a crucial aspect. As sites of large gatherings and dense living conditions, cities offer the perfect settings for the spread of infection, yet their role seems to have often gone unremarked in discussions of the pandemic.

On May 6, Médecins Sans Frontières (MSF) announced it had started to treat COVID-19 patients in Tijuana, in northwestern Mexico. Tijuana, which is on the border with San Diego, has the greatest number of cases in Mexico and one of the highest death rates.

“We will be providing support to health institutions [by] relieving the hospital burden in Tijuana,” said Maria Rodríguez Rado, MSF’s COVID-19 Emergency Response Coordinator in Mexico, according to the group’s website. “Through this support, we want to relieve the enormous workload of health workers who are responding to this pandemic and help alleviate the suffering of patients.”

The move is welcome. Across Central America, megacities such as Guatemala City, Tegucigalpa in Honduras, and Managua in Nicaragua are vulnerable to the rapid spread of COVID-19.

Safe water, sanitation, and hygiene (WASH) are vital for human well-being. However, 1 in 3 people (approximately 2.2 billion) still lack safe drinking water, 4.2 billion do not have access to safely managed sanitation services, and 829,000 people die annually from unsafe water and related sanitation and hygiene around the world.

Doula Village lies 55 kilometers (34 miles) northeast of New Delhi on a flat expanse of Uttar Pradesh farmland close to the Hindon River. Until the 1980s Doula Village’s residents, then numbering 7,000, and its farmers and grain merchants, thrived on land that yielded ample harvests of rice, millet, and mung beans. The bounty was irrigated with clean water transported directly from the river, or with the sweet groundwater drawn from shallow wells 7 meters (23 feet) deep.

Huo Chang grows visibly exasperated as he speaks about his city’s water crisis. From his office in Beijing’s largest state-owned environmental investment and service company, China Energy Conservation and Environmental Protection Group (CECEP), the water expert explains how Beijing is in the throes of a population and economic boom that has left its water resources both polluted and depleted. In response to these opposing pressures, the city turned to controversial measures to avoid a Cape Town-like Day Zero crisis in which Beijing would no longer be able to meet the daily water needs of its population of nearly 22 million.

For this World Cities Day, the UN’s theme calls for “building sustainable and resilient cities.” Cities across the Global South are assessing their physical preparedness against future shocks. Can cities that leave out—or often push out—poor workers claim resiliency? These moves are, in fact, weakening any preparedness. The foundations of truly sustainable and resilient cities lie in their residents’ abilities and agency.

 This is what a water panic looks like in a major global city.

People hoard water. They queue for hours, well into the night, to fill jugs at natural springs. Like mad Christmas shoppers, they clear supermarkets of bottled water. They descend on stockers before they can fill the shelves.

“The idea to make this film came from a very personal place,” said filmmaker Luciana Kaplan at a recent Wilson Center screening of her documentary Rush Hour, recalling how a woman who worked for her spent six hours a day on public transportation. “I have to make a film about this,” she said she told herself, “because this is a silent enemy that is attacking all of us in big cities.”