The disproportionately high COVID-19 infection rates observed in Black Americans could be linked to their daily commuting patterns

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The disproportionately high COVID-19 infection rates observed in Black Americans could be linked to their daily commuting patterns, according to a new study published today in the Journal of the Royal Society Interface.

The research found that increased exposure to other ethnic groups, for example as a result of an individual’s job or use of public transport, can result in the emergence of an “infection gap” in the population, such as the abnormally high incidence of COVID-19 recorded in Black Americans.

In some areas of the US COVID-19 incidence in Black Americans can be up to three to five times higher than would be expected based on population data. Previous studies have highlighted socio-economic factors including lower income and poorer access to healthcare facilities could play a role in this infection gap but these factors alone cannot completely explain the disproportionate impact of the pandemic on Black Americans.

In the study, researchers from Queen Mary University of London considered the impact of residential segregation, whereby different ethnic groups tend to live in the areas where the majority of people are from the same background, as well other forms of segregation individuals might experience due to their daily activities, such as commuting.

To do this, they examined the relationship between ‘diffusion segregation’, which measures the probability for a given group of people to come into contact with groups of other ethnicities, and weekly COVID-19 incidence during the early phases of the pandemic.

The research team analysed US census data collated from over 130 metropolitan areas to create two types of geographical networks. Adjacency graphs were used to map connections between bordering census areas and commuting graphs instead showed daily commuting flows across the US.

They then simulated random walks over those graphs, as a way to explore different paths among census tracts and determine how long it would take for a person starting from a given census tract to encounter individuals from any another ethnic group for the first time.

Using this approach the researchers showed that those areas where Black Americans were more exposed to other ethnicities, as well as the regions where they were more internally clustered, also observed a higher infection gap i.e. a larger impact of COVID-19 infections on this ethnic group.

When mobility was later restricted due to lockdown measures the researchers found that public transport usage instead strongly correlated with the infection gap observed in different US regions.

Aleix Bassolas, Postdoctoral Research Assistant at Queen Mary, said: “The study suggests that taking into account daily commuting patterns of a social or ethnic group can be enough to explain most of the differential incidence of COVID-19 in African American communities during the first epidemic wave last year.”

“For us it was surprising that quite a simple model, was able to show such a consistently high level of association between social segregation and the excessive incidence of COVID-19 observed in African Americans,” added Sandro Sousa, author of the study and Ph.D. student at Queen Mary.

The researchers analysed the impact of several other socio-economic factors on the disproportionately high infection and death rates observed in Black Americans. They found that when looking at infection rates, diffusion segregation alone could explain the observed infection gap relatively well. However, other socio-economic factors, such as life expectancy or access to healthcare services, became more important when understanding the disproportionately high death rates due to COVID-19 in this ethnic group.

Dr. Vincenzo Nicosia, Lecturer in Networks and Data Analysis, at Queen Mary said: “Our results confirm that knowing where people have to commute to, rather than where they live, is potentially much more important to curb the spread of a non-airborne disease.

Policy makers need to take into account specific mobility patterns and needs, as well as differences in the mobility and commuting habits of different ethnic and social groups, when deciding on the most effective non-pharmaceutical countermeasures against COVID-19 and similar non-airborne diseases.”

“We believe this type of analysis could be applied to other countries, such as the UK, however this is dependent on having access to more detailed activity and commuting data, which isn’t readily available in all countries.”


Coronavirus Disease 2019 (COVID-19), caused by infection with Severe Acute Respiratory Syndrome Coronavirus-2, has been declared by the World Health Organization to be a pandemic, with over seven million confirmed cases in the United States [1, 2]. New York State, including the New York City, became the epicenter of the epidemic in the United States, accounting for more than 23% of the total U.S. cases by the end of May, 2020 [2].

Such burden of disease is of particular concern since it disproportionately affects communities with considerable health disparities in New York City, where African-Americans and Latinos constitute as much as 53% of the population [3]. Our medical center is located in such a community in Brooklyn, New York.

The spectrum of COVID-19 presentation ranges from mild influenza-like illness to life-threatening severe respiratory disease requiring ventilatory support [3]. Comorbid conditions such as hypertension, diabetes mellitus, pulmonary and heart diseases, and demographic factors have been reported to influence outcomes [4–6].

However, the relative influence of each of these comorbidities in different patient populations and age strata has not been assessed, leading to variability in management and outcomes. Key decisions in patient management such as the choice of antibiotic, blood pressure goals, and perhaps most importantly, airway management strategies, have remained variable across or within hospitals.

National health statistics have documented extensive health disparities for Black COVID-19 patients. They suffer a three-fold greater infection rate, and a six-fold greater mortality rate than their white counterparts [7]. However, limited clinical and laboratory data of prognostic significance from Black COVID-19 patients are available [8]. A range of cultural, linguistic, and healthcare access barriers have prevented clinical investigation. Our hospital, located in New York City, serves a predominantly Black population, and being declared a COVID-only facility, we were able to maintain a standard quality-of-care across all COVID-19 patients.

Here we explore the clinical aspects of COVID-19 and its outcomes in Black patients. This study evaluated clinical signs and symptoms, laboratory indicators, and management strategies to develop a data-driven COVID-19 patient-care approach. Our findings provide an evidence-based resource for physicians to assess patient progress in the early days of hospitalization to direct patient management decisions.

Background
African-Americans/Blacks have suffered higher morbidity and mortality from COVID-19 than all other racial groups. This study aims to identify the causes of this health disparity, determine prognostic indicators, and assess efficacy of treatment interventions.

Methods
We performed a retrospective cohort study of clinical features and laboratory data of COVID-19 patients admitted over a 52-day period at the height of the pandemic in the United States. This study was performed at an urban academic medical center in New York City, declared a COVID-only facility, serving a majority Black population.

Results

Of the 1103 consecutive patients who tested positive for COVID-19, 529 required hospitalization and were included in the study. 88% of patients were Black; and a majority (52%) were 61–80 years old with a mean body mass index in the “obese” range. 98% had one or more comorbidities. Hypertension was the most common (79%) pre-existing condition followed by diabetes mellitus (56%) and chronic kidney disease (17%).

Patients with chronic kidney disease who received hemodialysis were found to have lower mortality, than those who did not receive it, suggesting benefit from hemodialysis Age > 60 years and coronary artery disease were independent predictors of mortality in multivariate analysis. Cox proportional hazards modeling for time to death demonstrated a significantly high ratio for COPD/Asthma, and favorable effects on outcomes for pre-admission ACE inhibitors and ARBs. CRP (180, 283 mg/L), LDH (551, 638 U/L), glucose (182, 163 mg/dL), procalcitonin (1.03, 1.68 ng/mL), and neutrophil:lymphocyte ratio (8.3:10.0) were predictive of mortality on admission and at 48–96 h. Of the 529 inpatients 48% died, and one third of them died within the first 3 days of admission. 159/529patients received invasive mechanical ventilation, of which 86% died and of the remaining 370 patients, 30% died.

Conclusions

COVID-19 patients in our predominantly Black neighborhood had higher in-hospital mortality, likely due to higher prevalence of comorbidities. Early dialysis and pre-admission intake of ACE inhibitors/ARBs improved patient outcomes. Early escalation of care based on comorbidities and key laboratory indicators is critical for improving outcomes in African-American patients.

reference link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7812567/


More information: ‘Diffusion segregation and the disproportionate incidence of COVID-19 in African American communities’ Aleix Bassolas, Sandro Sousa and Vincenzo Nicosia, Journal of the Royal Society Interface, DOI: 10.1098/rsif.2020.0961

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