Investigating COVID-19 transmission and mortality differences between indigenous and non-indigenous populations in Mexico

Comparative analysis of COVID-19 diagnoses and mortality among hospitalized indigenous and non-indigenous populations in Chile: 2020-2021

BACKGROUND

Current literature presents mixed effects of the COVID-19 pandemic on Indigenous communities. We aim to highlight potential disparities and temporal shifts in both the impact of COVID-19 and vaccine uptake among hospitalized Indigenous populations in Chile.

METHODS

We conducted an observational analysis utilizing 1,598,492 hospitalization records from 2020 to 2021 based on publicly accessible hospital discharge data spanning 65 healthcare facilities of medium and high complexity funded through the Diagnosis-Related Groups (DRG) mechanism in Chile, representing roughly 70% of the country's total hospitalizations. This was supplemented with publicly available municipal data on COVID-19 vaccinations and socio-demographic variables. We performed logistic regression analysis at 0.05 level of significance to assess the bivariate and multivariable association of Indigenous status with COVID-19 diagnosis and COVID-19 deaths among hospitalized populations. We also performed univariate and multiple linear regression to assess the association of COVID-19 vaccination rate and Indigenous status at the municipality level. In addition, we report the distribution of top 10 secondary diagnoses among hospitalized COVID-19 cases and deaths separately for Indigenous and non-Indigenous populations.

RESULTS

Indigenous populations displayed lower adjusted odds for both COVID-19 diagnosis (OR: 0.76, 95% CI: 0.74, 0.77) and death (OR: 0.91, 95% CI: 0.85, 0.97) when compared to non-Indigenous groups. Notably, the adjusted odds ratio for COVID-19 diagnosis in Indigenous populations rose from 0.59 (95% CI: 0.57, 0.61) in 2020 to 1.17 (95% CI: 1.13, 1.21) in 2021. Factors such as the significantly higher median age and greater number of comorbidities in the non-Indigenous hospitalized groups could account for their increased odds of COVID-19 diagnosis and mortality. Additionally, our data indicates a significantly negative adjusted association between COVID-19 vaccination rates and the proportion of Indigenous individuals.

CONCLUSION

Although Indigenous populations initially showed lower odds of COVID-19 diagnosis and mortality, a marked rise in diagnosis odds among these groups in 2021 underscores the urgency of targeted interventions. The observed negative association between the proportion of Indigenous populations and vaccination rates further underscores the necessity to tackle vaccine access barriers and work towards equitable distribution.

Effect of vaccination on COVID-19 mortality during omicron wave among highly marginalized mexican population

Background

Social determinants have played a role in COVID-19 outcomes and vaccination has improved these and impacted on inflammatory response, we therefore sought to investigate the association between vaccination and inflammatory response with COVID-19 mortality in a Mexican population with high marginalization during the Omicron wave.

Methods

Prospective, longitudinal, single-center study in a setting of high marginalization conducted during the Omicron wave, from January to November 2022. Clinical and laboratory data were collected during admission and patients were followed until discharge or death. Patients were grouped according to outcome (survival and non-survival), and by complete (2 or more doses) and incomplete vaccination status for comparison.

Results

118 patients were included, 54% (64/118) male, with a median age 63 years and 86% (102/118) with self-reported comorbidities. Mortality was 42%. 58% (68/118) had complete vaccination. There was a 64% risk reduction for all-cause in-hospital mortality of having complete vaccination, hazard ratio 0.36, (95% CI 0.18-0.71, p = 0.004) in the proportional hazards Cox regression test. Survivor group arrived earlier to medical care and had higher SpO2 on admission, and for inflammatory response, had lower levels of Neutrophil-to-lymphocyte ratio, C-reactive protein, and D-dimer at admission. In the longitudinal measurement, only D-dimer showed significant differences between groups according to survival.

Conclusion

In a highly marginalized Mexican population, complete vaccination has a protective effect against COVID-19 all-cause in-hospital mortality compared with incomplete or no vaccination. However, mortality in this population during the Omicron wave is high. Socio-economic inequalities may play an important role in COVID-19 outcomes.

COVID-19 vaccine uptake and barriers among Indigenous language speakers in Mexico: Results from a nationally representative survey

Mexico faced a significant burden from the COVID-19 pandemic. Since the pandemic's onset in 2020, numerous studies have underscored the substantial risk of COVID-19 death among Indigenous individuals. This study aims to assess COVID-19 vaccine uptake among Indigenous language speakers in Mexico, focusing on understanding the barriers they face in obtaining access to vaccines. We used Encuesta Nacional de Salud y Nutrición Continua (ENSANUT) 2022, a nationally representative health survey in Mexico to analyze data on self-reported COVID-19 vaccine status, reasons for not getting vaccinated, and other relevant covariates. We employed logistic regression to estimate odds ratios (ORs) for vaccine uptake and uptake barriers, all models were adjusted for potential confounders. Among 34,051 participants, 1793 individuals (5.23%) reported speaking an Indigenous language. Indigenous language speakers were found to have a lower vaccination rate (63%) compared to non-Indigenous language speakers (81%) (p <0.005). They were also 59% less likely to be vaccinated against COVID-19 (OR 0.41, 95% CI 0.27-0.62), even when adjusted for confounders. Among unvaccinated individuals, Indigenous language speakers were more likely to cite negative beliefs about the vaccine or fear as reasons for not being vaccinated (OR 1.82, 95% CI 1.11-3.00) while being less likely to report access barriers (OR 0.62, CI 95% 0.42-0.91). This study highlights disparities in COVID-19 vaccine uptake among Indigenous language speakers in Mexico. The findings underscore the urgent need for targeted, culturally appropriate public health interventions and the consideration of social and ethnic vulnerability in prioritizing vaccinations.

How Education Shapes Indigenous Health Inequalities in the USA and Mexico

Indigenous peoples around the world face significant health disparities relative to the dominant groups in their countries, yet the magnitude and patterns of health disparities vary across countries. We use data from the National Health Interview Survey and Mexican Family Life Survey to examine the health of Indigenous peoples in Mexico and American Indians and Alaska Natives in the USA and to evaluate how they fare relative to the majority populations in their countries (non-Indigenous Mexicans and non-Hispanic Whites, respectively). We assess disparities in self-rated health and activity limitations, with a focus on how Indigenous health disparities intersect with educational gradients in health. Regression analyses reveal three primary findings. First, Indigenous health disparities are larger in the USA than in Mexico. Second, differences in educational attainment account for most of the differences between Indigenous and non-Indigenous populations in Mexico, but less than half in the USA. Third, in both countries, health is moderated by educational attainment such that between-group disparities are largest at the highest levels of education. However, for Indigenous Mexicans there is a "cross-over" in which Indigenous Mexicans report better health at the lowest level of education. Overall, this study finds a weak relationship between education and Indigenous health, and raises the question about the validity of using traditional measures of SES in Indigenous contexts.

Age-specific mortality and the role of living remotely: The 1918-20 influenza pandemic in Kautokeino and Karasjok, Norway

The 1918-20 pandemic influenza killed 50-100 million people worldwide, but mortality varied by ethnicity and geography. In Norway, areas dominated by Sámi experienced 3-5 times higher mortality than the country's average. We here use data from burial registers and censuses to calculate all-cause excess mortality by age and wave in two remote Sámi areas of Norway 1918-20. We hypothesise that geographic isolation, less prior exposure to seasonal influenza, and thus less immunity led to higher Indigenous mortality and a different age distribution of mortality (higher mortality for all) than was typical for this pandemic in non-isolated majority populations (higher young adult mortality & sparing of the elderly). Our results show that in the fall of 1918 (Karasjok), winter of 1919 (Kautokeino), and winter of 1920 (Karasjok), young adults had the highest excess mortality, followed by also high excess mortality among the elderly and children. Children did not exhibit excess mortality in the second wave in Karasjok in 1920. It was not the young adults alone who produced the excess mortality in Kautokeino and Karasjok. We conclude that geographic isolation caused higher mortality among the elderly in the first and second waves, and among children in the first wave.

Inequity in mortality rates and potential years of life lost caused by COVID-19 in the Greater Santiago, Chile

Several studies have shown that, in Chile, income inequality is relevant in explaining health inequities. The COVID-19 pandemic has also had a negative impact, with higher mortality rates in those municipalities of Greater Santiago with lower socioeconomic status. We study inequity in mortality based on Potential Years of Life Lost (PYLL) in 34 urban municipalities of the Metropolitan Region (Greater Santiago) and analyze its evolution between 2018 and 2021 and by COVID-19 waves. To compare the results obtained for PYLL, we also computed the mortality rates adjusted by direct standardization. In addition, we used the concentration index (CI) to measure the health inequalities between municipalities. In the first year of the pandemic, the absolute PYLL and the standardized mortality rate for all causes of death showed an increase of 13.6% and 18.9%, respectively. Moreover, 409,086 years of life were prematurely lost in 2020, one-fifth of them due to COVID-19. The concentration indices confirm inequality in both mortality rates and PYLL, where it is more pronounced when calculating the latter measure. Results show that the deaths due to the COVID-19 pandemic affected the most economically disadvantaged municipalities, and particularly young people in those places.

Indigenous communities and influenza: protocol for a systematic review and meta-analysis

BACKGROUND

Several studies have documented that specific Indigenous groups have been disproportionately affected by previous pandemics. The objective of this paper is to describe the protocol to be used in a review and meta-analysis of the literature on Indigenous groups and influenza. Using this protocol as a guide, a future study will provide a comprehensive historical overview of pre-COVID impact of influenza on Indigenous groups by combining data from the last five influenza pandemics and seasonal influenza up to date.

METHODS/PRINCIPLE FINDINGS

The review will include peer-reviewed original studies published in English, Spanish, Portuguese, Swedish, Danish, and Norwegian. Records will be identified through systematic literature search in eight databases: Embase, MEDLINE, CINAHL, Web of Science, Academic Search Ultimate, SocINDEX, ASSIA, and Google Scholar. Results will be summarized narratively and using meta-analytic strategies.

DISCUSSION

To our knowledge, there is no systematic review combining historical data on the impact of both seasonal and pandemic influenza on Indigenous populations. By summarizing results within and across Indigenous groups, different countries, and historical periods, as well as research in six different languages, we aim to provide information on how strong the risk for influenza is among Indigenous groups and how consistent this risk is across groups, regions, time, and seasonal versus the specific pandemic influenza strains.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42021246391.

COVID-19 infection and mortality among non-pregnant indigenous adults in Mexico 2020-2022: Impact of marginalisation

Background

Indigenous individuals have higher rates of mortality and poverty in Mexico and more than half are marginalised, and COVID-19 pandemic aggravated the existing burden of health disparities. We aimed to analyse the effects of being indigenous and marginalised on coronavirus (COVID-19) infection fatality in Mexico.

Methods

We identified 3 424 690 non-pregnant, COVID-19 positive adults ≥19 years in the Mexico national COVID-19 database with known date of symptom. We used demographic information, indigenous status, marginalisation status, and co-morbidities in binary logistic regression to predict mortality, adjusting for covariates, including hospitalisation, admission to the intensive care unit (ICU), and mechanical ventilation use. We also assessed the interaction between indigenous status and marginalisation.

Results

Marginalisation was much higher among indigenous (53.7%) compared to non-indigenous individuals (4.8%). COVID-19 fatalities were approximately 20 years older (64.4 and 63.0 years) than survivors (44.7 and 41.2 years) among indigenous vs non-indigenous individuals, respectively. The unadjusted risk of COVID-19 fatality among indigenous individuals was nearly two-fold (odds ratio (OR) = 1.92)) compared to non-indigenous individuals (OR = 1.05). COVID-19 fatality was higher among highly marginalised individuals (upper quartile) (OR = 1.51; 95% confidence interval (CI) = 1.49-1.54). Marginalised indigenous individuals had a significantly lower likelihood of ICU admission compared to non-indigenous non-marginalised individuals. The likelihood of mechanical ventilation for indigenous individuals was 4% higher compared to non-indigenous individuals. Indigenous marginalised individuals had a significantly lower probability of mechanical ventilation compared to non-indigenous non-marginalised individuals. COVID-19 comorbidity risks of fatality significantly differed between the two groups in the Cox survival analysis. In the fully adjusted model, indigenous individuals were 4% more likely to die from COVID-19 compared to non-indigenous.

Conclusions

Indigenous, marginalised individuals with COVID-19 had higher risk of hospitalisation and ICU admission than non-indigenous patients. Marginalised, indigenous individuals were less likely to receive mechanical ventilation compared to non-indigenous, but had a higher risk of COVID-19. Indigenous individuals had a 4% higher COVID-19 mortality risk COVID-19 compared to non-indigenous individuals. Improved community medical care and augmented health services in rural hospitals could mitigate barriers to health care access in indigenous, marginalised populations.

Ethnic inequalities in COVID-19 infection, hospitalisation, intensive care admission, and death: a global systematic review and meta-analysis of over 200 million study participants

Background

COVID-19 has exacerbated existing ethnic inequalities in health. Little is known about whether inequalities in severe disease and deaths, observed globally among minoritised ethnic groups, relates to greater infection risk, poorer prognosis, or both. We analysed global data on COVID-19 clinical outcomes examining inequalities between people from minoritised ethnic groups compared to the ethnic majority group.

Methods

Databases (MEDLINE, EMBASE, EMCARE, CINAHL, Cochrane Library) were searched from 1st December 2019 to 3rd October 2022, for studies reporting original clinical data for COVID-19 outcomes disaggregated by ethnicity: infection, hospitalisation, intensive care unit (ICU) admission, and mortality. We assessed inequalities in incidence and prognosis using random-effects meta-analyses, with Grading of Recommendations Assessment, Development, and Evaluation (GRADE) use to assess certainty of findings. Meta-regressions explored the impact of region and time-frame (vaccine roll-out) on heterogeneity. PROSPERO: CRD42021284981.

Findings

77 studies comprising over 200,000,000 participants were included. Compared with White majority populations, we observed an increased risk of testing positive for infection for people from Black (adjusted Risk Ratio [aRR]:1.78, 95% CI:1.59-1.99, I2 = 99.1), South Asian (aRR:3.00, 95% CI:1.59-5.66, I2 = 99.1), Mixed (aRR:1.64, 95% CI:1.02-1.67, I2 = 93.2) and Other ethnic groups (aRR:1.36, 95% CI:1.01-1.82, I2 = 85.6). Black, Hispanic, and South Asian people were more likely to be seropositive. Among population-based studies, Black and Hispanic ethnic groups and Indigenous peoples had an increased risk of hospitalisation; Black, Hispanic, South Asian, East Asian and Mixed ethnic groups and Indigenous peoples had an increased risk of ICU admission. Mortality risk was increased for Hispanic, Mixed, and Indigenous groups. Smaller differences were seen for prognosis following infection. Following hospitalisation, South Asian, East Asian, Black and Mixed ethnic groups had an increased risk of ICU admission, and mortality risk was greater in Mixed ethnic groups. Certainty of evidence ranged from very low to moderate.

Interpretation

Our study suggests that systematic ethnic inequalities in COVID-19 health outcomes exist, with large differences in exposure risk and some differences in prognosis following hospitalisation. Response and recovery interventions must focus on tackling drivers of ethnic inequalities which increase exposure risk and vulnerabilities to severe disease, including structural racism and racial discrimination.

Funding

ESRC:ES/W000849/1.