Study says pollution can be used to predict Covid cases

Study says pollution can be used to predict Covid cases
Study says pollution can be used to predict Covid cases

Maria Fernanda Ziegler | FAPESP Agency – A study carried out by researchers from the universities of São Paulo (USP), Leeds (United Kingdom) and Harvard (United States) suggests that indicators of pollution and mobility can also be used to predict the increase in the number of cases and deaths from COVID-19.

In an article published on the medRxiv platform, still without peer review, the authors report that even slight reductions in the rates of mobility and pollution observed in the city of São Paulo were reflected in a considerable drop in the number of new infections and deaths in the days following.

“But it is important to emphasize that it is a purely mathematical study”, says Edmilson Dias de Freitas, professor at the Institute of Astronomy, Geophysics and Atmospheric Sciences (IAG-USP) and author of the study, which was supported by FAPESP through several projects (15 / 03804-9, 16 / 18438-0 and 16 / 10557-0).

Pollution and mobility indicators help to predict deaths from COVID-19- Photo: Rovena Rosa / Agência Brasil

By correlating patterns of social distance, epidemiological, pollution and meteorological data, authors calculated that an isolation rate of 45.28% in the capital is associated with 1,212 new cases of COVID-19 and 44 new deaths. However, when the movement of people is reduced, that is, the isolation rate increases to 50%, it is possible to reduce the number of cases of the disease to 438 and still avoid almost half of deaths.

The analysis was carried out by atmospheric science researchers who are part of research projects supported by FAPESP. The social isolation index of the Intelligent Monitoring System (SIMI-SP) was monitored throughout the pandemic by means of non-personalized data provided by mobile operators. In addition to this indicator, Google’s residential mobility index was assessed.

The SIMI-SP isolation rate of 45.28% is the median in the city of São Paulo, an index that in the study was best associated with the epidemiological data of COVID-19 in the city. On March 16, 2021, when São Paulo entered the most restrictive phase and broke the record for deaths from COVID-19, the isolation rate was 42%.

“In addition to finding statistical associations between COVID-19 and the isolation index, we also observe well-defined weather patterns. This means that when there was an increase in mobility, it was possible to observe an increase in cases from four to nine days later and, from 18 days on, an increase in the number of deaths ”, reports Sergio Ibarra-Espinosa, researcher at IAG -USP and lead author of the study.

Although the study did not take into account specific factors of the disease, the data are in line with the development of COVID-19. In general, a person infected with SARS-CoV-2 takes four to nine days to develop symptoms.

“There are very clear standards, which makes this indicator important for the formulation of public policies. In the same way that it shows that more social distance can prevent deaths, the opposite is also true. The greater the movement in the city, the greater the number of cases and deaths due to COVID-19, which was observed with the increase in the circulation of people at the holidays and other holidays ”, comments Amanda Rehbein, FAPESP scholarship holder at IAG-USP and co-author of the study.

Peak transmission and potential collapse

The researchers used data collected between March 27, 2020 and March 12, 2021 (before the peak of the pandemic) and, therefore, the study does not consider the possibility of saturation of the health system or any measure in relation to the use of masks. , hygiene procedures or financial aid for the population to remain at home.

“Therefore, the impact can be significantly greater with the saturation of the health system and the compromise of adequate treatment for all patients. After all, the relationships observed over the study period did not include the lack of emergency care, which is a fundamental factor in relation to the number of deaths ”, says Freitas.

The researchers also noted that an increase in particulate material and ozone in the atmosphere was associated with an increase in cases and deaths from COVID-19. “We still don’t know the reason for this association. As it is a respiratory disease, pollution may interfere with the aggravation. Another possibility is that the pollution indexes are indicators of mobility, since particulate material and ozone are associated with the burning of fossil fuels ”, says Freitas.

The article Association between COVID-19, mobility and environment in São Paulo, Brazil can be read at www.medrxiv.org/content/10.1101/2021.02.08.21250113v1.

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