Background
Emerging evidence has highlighted the stark racial and ethnic disparities in the risk of infection and death caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for COVID-19. In the United States, African American, Latinx, and indigenous populations have been disproportionately affected by COVID-19-related infections and associated morbidity and mortality [
1‐
4]. Notably, these disparities have mirrored trends observed in prior epidemics of other viral acute respiratory infections (ARI). During the 1918 influenza pandemic, Black Americans were more likely to die compared to their white counterparts [
5]. Most recently, during the 2009 H1N1 influenza pandemic, minority groups were more likely to be hospitalized and to die compared to non-Hispanic white populations [
6,
7]. The purpose of this systematic review is to investigate racial and ethnic disparities in morbidity and mortality of prior outbreaks, epidemics, and pandemics of ARI to provide context in understanding the disparate impact of the current COVID-19 epidemic across the United States.
Despite the growing interest to explore literature concerning racial disparities and social determinants of ARI, there are no systematic reviews comprehensively characterizing research focused on racial and ethnic disparities from former infectious disease outbreaks of viral respiratory pathogens [
8]. Aside from recent literature concerning SARS-CoV-2, there is a lack of research documenting racial disparities in prior outbreaks or pandemics. However, there is existing evidence of racial disparities involving ARI. In the United States, research has shown that Black children have higher rates of hospitalizations from ARI compared to white children, although they do not differ in severity of disease once hospitalized [
9]. There has also been evidence that acute infections can contribute to racial disparities in stroke-related deaths; however, this included non-respiratory tract infections in addition to ARI [
10].
Considering the ever-growing focus on the contribution of racial inequities to multiple facets of health, and the present burden of COVID-19-related deaths on African-American, Latinx, and indigenous communities in the current pandemic, it is imperative to understand factors, including structural racism, that have contributed to these disparities in earlier outbreaks. Such knowledge would inform development of a pandemic preparedness response that ensures protection of the most vulnerable.
Framing pandemic preparedness through a social justice lens is not a novel concept and has been previously emphasized as integral to mounting an effective response strategy [
11‐
13]. Nevertheless, underscoring the protection of groups at highest risk of disease burden based on socioeconomic factors defining living and working conditions has yet to be incorporated into existing national strategies [
14]. By failing to protect the most vulnerable, we not only miss the opportunity to prevent and mitigate disease burden among those at highest risk and in the population as a whole, but also inadvertently perpetuate the systemic inequities that contribute to ongoing health disparities in minority communities. A deepened understanding of the scale and drivers of racial disparities in ARI attributable to structural and systemic inequities will not only prevent further disparities from occurring in the event of future outbreaks or pandemics but can also alleviate present disparities in endemic ARI.
To address the gaps in the literature, the aim of this systematic review is to synthesize the racial and ethnic disparities in the incidence, morbidity, and mortality of viral acute respiratory infections from 2002 onward in the United States. This review also aims to determine which racial/ethnic populations are disproportionately affected and evaluate underlying drivers of these disparities including structural racism. We will also describe the individual-, community-, and structural-level factors correlated with race/ethnicity, including social determinants of health such as socio-economic status, geography/neighborhood, healthcare accessibility, which are associated with increased morbidity and mortality in acute respiratory infections.
Confidence in cumulative evidence
For quantitative studies, we will assess the quality of the body of evidence contributing to the pooled effect estimate for each outcome using criteria recommended by the Grading of Recommendations Assessment, Development and Evaluation (GRADE) Working Group: GRADE evidence certainty for individual outcomes [
25‐
30]. We will assess the quality of evidence across the following domains: risk of bias, consistency, directness, precision, and publication bias. We may consider additional domains if appropriate. Funnel plots will be used to assess for risk of publication bias across individual studies where 10 or more similar studies are included. If study protocols are available, we will compare the outcomes reported in the protocol to those in the published report to assess for selective outcome reporting. If protocols are not available, we will compare the outcomes reported in the methods and results sections of the published study. Finally, we will compare the fixed effect estimate to the random effects model to determine whether small sample bias exists.
Discussion
The aim of this review is to investigate disparities in morbidity and mortality in acute respiratory viral infections other than SARS-CoV-2. Some practical challenges are expected in the identification of existing evidence. First, although we are focusing our search on racial and ethnic disparities in ARI outcomes, our search strategy will not filter out articles based on specific race or ethnicity terms from the title screening, as these terms may not be present. Instead, we will assess for the presence of racial and ethnic comparisons during the abstract screening phase. Furthermore, the medical library indexing of articles may influence the results obtained in this review. It is common practice to report outcomes by race; however, if differential outcomes are not a primary objective of the study, the article may not be indexed in the medical library accordingly and therefore may not be represented in this review, or it will be excluded. If we are unable to identify any relevant articles, we will consider expanding our search terms and will document any changes to the protocol in PROSPERO and the final manuscript of the review, which is intended for publication.
Second, racial and ethnic disparities are documented to be associated with interrelated socioeconomic factors representing macrolevel inequalities such as income, neighborhood, stigma and discrimination, and barriers or access to healthcare [
11]. Given this, studies may focus on upstream determinants of racial disparities, or manifestations of structural inequalities other than race. The search protocol has been developed to consider this complexity; however discerning intersecting factors is an expected challenge of this review. Lastly, under-representation of racial and ethnic minorities in clinical trials has been documented in other contexts [
31]. Specifically, historical ethics violations of human subjects’ research have disproportionately affected minorities in the United States and potentially deterred study participants from minority communities. Therefore, study populations may not be representative of racial and ethnic minorities. These potential challenges may limit the comprehensiveness of this review and therefore limit the conclusions.
The findings from this systematic review will provide context and insight to understand patterns of disparity in viral acute respiratory infections in the United States. Furthermore, this review may support a robust comprehension of the manifestations of structural and social inequities affecting racial and ethnic minorities and their influence on ARI outcomes. Leveraging this information could influence development and implementation of studies on the differential impact of COVID-19 across the United States. Moreover, this information could be used to inform the development of resource-based strategies facilitating the prevention of both acquisition and onward transmission to alleviate the structural inequities driving racial and ethnic disparities prevalent in ARI. Finally, the Biden-Harris Administration have proposed the establishment of a COVID-19 Racial and Ethnic Disparities Task Force as an integral component of their plans to address the ongoing COVID-19 pandemic and pandemic preparedness moving forward [
32]. We expect that that the results of this systematic review adds to the body of evidence that will drive future decision-making of this task force by reigniting a focus on pandemic preparedness and public health responses to other ARI that underscores the anticipation of disparities and the implementation of equitable and human rights affirming programs to mitigate them.
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