COVID-19: A need to go out to work explains why some areas have more cases than others

A study of São Paulo city shows that neighborhoods with more hospitalizations and deaths from coronavirus coincide with areas whose inhabitants have been unable to shelter at home.

By Maria Fernanda Ziegler  |  Agência FAPESP – There is a significant correlation between the circulation of people who need to work during the pandemic and the parts of São Paulo city (Brazil) in which the number of cases of COVID-19 is highest. Neighborhoods such as Cidade Ademar, Brasilândia, Sapopemba and Capão Redondo, which have reported the most hospitalizations in the city, coincide with those whose inhabitants have been unable to stay at home despite the social distancing measures imposed during the period.

“Workers in essential sectors, especially the healthcare and food sectors, as well as domestic workers and other people who have to keep working to maintain their income, are more exposed to the risk of infection and even death. Most of these workers use public transport,” said Raquel Rolnik, a professor at the University of São Paulo’s School of Architecture and Urbanism (FAU-USP), where she co-chairs the Public Space and Right to the City Laboratory (Labcidade).

Rolnik led a study conducted in partnership with Instituto Pólis, a public policy think tank, to look for correlations between areas of the city with the most hospitalizations of COVID-19 patients according to statistics supplied by SUS, the national health service, bus journeys according to SPTrans (which runs the city’s bus system), and commuting data from the latest origin-destination survey by Companhia do Metrô de São Paulo (São Paulo State’s Subway Company), excluding the contingent that may have switched to home working.

The study found that not all bus lines starting and ending in Capão Redondo, Jardim Ângela, Brasilândia, Cachoeirinha, Sapopemba, Iguatemi, Cidade Tiradentes, Itaquera and Cidade Ademar carried the most passengers during the quarantine. Another critical area is the city center, visited by many bus lines and representing an important origin or destination for large numbers of workers.

The available data cannot be used to verify whether contagion occurs during journeys, at the workplace, or in or near the workers’ home, Rolnik noted. “In any event, these buses with the most passengers ought to be retrofitted for passenger protection,” she told Agência FAPESP. “They should have personal protective equipment, face coverings and hand sanitizer, and there should be many more buses to avoid crowding. But that’s by no means all. It’s also very important to engineer social distancing in bus terminals and at bus stops using marquees, signage, and provisional spaces for people who are waiting.”

Another key finding is that care should be taken before precarious or crowded housing is blamed as the sole cause of high transmission rates. “We tested this hypothesis in the study and concluded that it isn’t sufficient to explain what has been happening,” Rolnik said. “Some densely populated areas with substandard housing have many cases, but others don’t. Similarly, some favelas are hotspots, while others have kept the level of transmission under control. Our study proves that in the case of São Paulo city, the decisive driver of contagion curve growth was the circulation of people who needed to work during lockdown, not least by bus and metro.”

Labcidade has been supported by FAPESP for several studies related to urban planning and regulation. During the pandemic, it has analyzed the impact of the disease on São Paulo and other cities in dimensions such as housing and transport, among others.

Hospitalizations and mobility

The analysis of coronavirus transmission in the city and how it is correlated with bus journeys is part of a series of studies conducted by the group. In a previous study, the researchers analyzed deaths and hospitalizations due to COVID-19 and SARS (severe acute respiratory syndrome) in terms of postcodes, showing that the disease did not occur uniformly throughout the city and that cases were concentrated in certain areas.

To understand how mobility during lockdown influenced the transmission of the disease, the researchers used GPS data from the buses that circulated between late May and early June 2020. “We applied for and obtained the data under freedom of information legislation,” Rolnik said. “The data told us how many people used buses and which bus lines had the most passengers in the period.”

The researchers also used data from origin-destination surveys conducted for the last 50 years by the state department of transportation, reflecting commuter preferences in the state capital. “We created a methodology to exclude journeys related to education, as schools and universities were closed in the period analyzed owing to the pandemic,” Rolnik said. “We also removed journeys by commuters with university degrees, executives, and professionals who had probably switched to remote working at the time. The result was a map of flows involving people who really had to leave home to work, which we correlated with the disease transmission data.”

More mobility after reopening

In light of the findings, the researchers are concerned about the gradual reopening of services and retail stores in the city. “The purpose of the study is to help provide a scientific basis for public policy. Reopening stores and easing social isolation will evidently lead to more movement of people, and transmission of the disease is also expected to increase as a result,” Rolnik said.

“I can understand that new stages of economic reopening are based on the health system’s capacity to provide care for the sick and on the occupancy of intensive care facilities. These are important metrics and must be taken into account, but there are others that should also be considered.”

The core of the workforce in this service sector that is reopening coincides with the group that was previously most exposed to the virus. “We’re talking about the same social group, and they’re going to be commuting without any additional protective measures,” Rolnik said.

The map of city areas with the highest contagion rates displays a perverse phenomenon. “It shows very clearly a division between those who have been able to self-isolate and work from home and those who have had to go out to work so that others could remain isolated,” she said.