The COVID-19 pandemic, caused by the SARS-CoV-2 virus, emerged in Wuhan, China in late 2019 and quickly escalated into a global health crisis with significant increase in morbidity and mortality (1). The first laboratory-confirmed case in the United States was reported by the CDC in January 2020 (2). The state of Michigan reported its first case on March 10, 2020, coinciding with the World Health Organization’s (WHO) declaration of COVID-19 as a global pandemic and Michigan’s Governor declaring a state of emergency (3, 4). By April 2020, Michigan became the third state to exceed 20,000 confirmed COVID-19 cases, highlighting the rapid spread of the virus and severe impact of the virus on the state’s population (5).

COVID-19 progressed in a series of waves, each marked by varying infection rates and disease severity. In Michigan, over the initial two years of the pandemic, more than 1.8 million cases were documented across five distinct waves (6). The first two waves were dominated by the wild-type strain of SARS-CoV-2 and included the initial wave (before October 10, 2020) and the holiday wave (October 1, 2020–March 7, 2021) (7). The third wave (March 7, 2021–June 27, 2021) was characterized by the emergence of the Alpha variant (8). The overall infection rates decreased during this period, coinciding with the public availability of vaccines in May 2021 (9). The fourth wave, (June 27, 2021–December 19, 2021), was dominated by the Delta variant, which led to a resurgence in cases due to its heightened transmissibility and potential for severe illness (10, 11). The fifth wave (December 19, 2021–June 18, 2022) was attributed to the rise of the Omicron variant. Although Omicron variant had higher infection rates, it generally caused milder symptoms compared to previous variants, a trend likely influenced by the mutated virus, higher vaccination rates and growing herd immunity (12, 13).

Research has consistently shown that minority populations, including African Americans or Black and Hispanic or Latino (HL) individuals, have experienced a disproportionately high burden of COVID-19 infections and related adverse health outcomes (14–16). However, the impact of the pandemic on other minority groups, such as Middle Eastern or Arab (MEA) individuals, remains understudied (17). Additionally, there has been limited exploration of how infection rates and vaccination uptake differ across racial and ethnic groups throughout the different waves of the pandemic.

In Michigan, the pandemic exacerbated existing health disparities, disproportionately affecting Michigan’s diverse population, including Black and MEA populations (18–21). Therefore, understanding these disparities and the impact of vaccination on infection rates is crucial for informing public health strategies and preparing for future public health crisis (22).

This study aims to assess disparities in COVID-19 infection rates and vaccination uptake among Middle Eastern or Arab, Black, and Hispanic or Latino populations compared to Caucasians or White population in Southeast Michigan across multiple pandemic waves. By identifying patterns of infection and risk factors contributing to disparities, these findings will provide actionable insights into the effectiveness of public health measures and highlight areas where targeted interventions are needed. Such efforts are crucial for improving preparedness for future pandemics and addressing long-standing health inequities.

This is a retrospective study, which was reviewed by the Corewell Health East (CHE) Institutional Review Board (IRB) and granted an exempt classification with a waiver of informed consent. We followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline for cohort studies.

To our knowledge, this is the first study to comprehensively assess COVID-19 positivity during distinct pandemic waves while considering vaccination status across different racial and ethnic groups, including Middle Eastern or Arab (MEA) individuals. White patients consistently had the lowest infection rates, even in the early waves of the pandemic when vaccines were not available. In addition, White patients had the highest vaccination rates compared to all other racial or ethnic groups. Our findings align with an established body of research that report significant racial and ethnic disparities in COVID-19 infection rates, hospitalization, and mortality (23). Additionally, several studies have shown that minority communities, particularly Hispanic/Latino (HL), Black, and MEA populations, were disproportionately affected by the pandemic, even when vaccination rates were not considered (18, 21, 24–26). Our findings align with a well-established body of research reporting significant racial and ethnic disparities in COVID-19 infection rates, hospitalizations, and mortality (23). Our analysis during the initial wave (prior to vaccine availability) revealed significantly higher odds of testing positive for COVID-19 among all minoritized groups compared to White patients. These disparities were largely driven by higher prevalence of chronic conditions (e.g., diabetes, hypertension) and social determinants of health, including limited access to healthcare, and increased exposure through essential work and multigenerational housing (27). Moreover, similar findings were reported from a retrospective cohort study of adult patients from diverse racial and ethnic backgrounds, tested for COVID-19 across 155 emergency departments during the early (March–June 2020) and late (July–September 2020) phases of the pandemic. Although that study phase definitions differ slightly from ours (initial wave defined as pre-October 2020), the timeframes largely overlap. This study found significantly higher adjusted odds of testing positive for COVID-19 among minoritized groups, including Hispanic/Latino and Black. Our analysis similarly revealed elevated odds of infection among these populations, highlighting persistent disparities in COVID-19 exposure and outcomes during the early stages of the pandemic (28). MEA patients who visited the ED, consistently showed high positivity rates throughout all pandemic waves compared to White patients, despite having similar vaccination rates. The similarity in vaccination rates could be attributed to the strong emphasis on vaccine awareness and disease prevention within the MEA communities (29, 30). Community leaders and healthcare providers may have effectively promoted vaccination within the MEA community (31, 32). Additionally, MEA individuals may have had better access to healthcare facilities and vaccination sites compared to other minority groups (33). However, MEA patients who presented to the ED experienced higher COVID-19 positivity rates throughout the pandemic, suggesting that factors beyond vaccination contributed to higher infection rates among this group. Several factors may have contributed to higher positivity rates among MEA. First, MEA population in this region are generally employed as essential workers and in services industries that had higher exposure to the virus. Second, factors such as multigenerational households, crowded living conditions and large family gatherings may have facilitated the spread of the virus (25). Third, lower socioeconomic status and limited access to healthcare services may have further exacerbated infection rates (34).

Our study shows that, compared to White patients, HL patients had consistently higher positivity rates across all pandemic waves and had lower vaccination rates. These findings are consistent with existing literature documenting disproportionate impact of COVID-19 on Hispanic communities (35, 36). Similar to MEA, Hispanic individuals work in essential jobs that require physical presence, increasing their risk of exposure (37). Many Hispanic families live in multigenerational households or crowded housing, which also facilitates virus transmission (38, 39). Furthermore, previous studies have shown that social determinants such as employment in essential services and lack of access to healthcare contribute significantly to higher infection rates among minority groups (15, 17). For example, limited access to healthcare and language barriers can delay testing and treatment, leading to higher infection rates (40). The lower vaccination rates in HL may be due to vaccine hesitancy and a lack of knowledge about vaccine efficacy and safety (41). Access barriers, such as difficulties in transportation, inflexible work schedules, fear of deportation for undocumented immigrants and language barriers, also likely played a role in hindering vaccination efforts (42, 43).

COVID-19 positivity rates for Black patients fluctuated across different pandemic waves. In addition, Black patients had the lowest vaccination rates compared to all other racial or ethnic groups. During the initial wave, higher infection rates among Black individuals could be attributed to increased exposure and a lack of adherence to public health measures, possibly due to the newness of the virus and limited information about its transmission. During the Holiday wave, the infection rate among the Black population were similar to the White population. Our findings were similar to previous studies that found non-Hispanic Black had lower infection rates during the Holiday surge compared to the initial wave (44). Additionally, a previous report showed that while Black and HL generally had higher overall infection rates than White individuals, only Black individuals had similar rates to White individuals during the Holiday and Delta waves (45).

The reduction in COVID-19 infection among Black individuals may be due to higher mortality in the initial wave which lead to enhanced fear among black community, resulting in social isolation and other mitigation efforts during the Holiday wave. For example, one study found Black individuals, after experiencing higher infection and mortality early in the pandemic, were less likely to have engaged in risky holiday gatherings in late 2020 (46). Furthermore, the lower COVID-19 infection rates in some Black communities during the holiday wave were likely due to targeted vaccination efforts by Black churches. For example, the National Black Church Initiative (NBCI) launched a campaign in early 2021, partnering with the CDC, mobilizing 150,000 churches, and hosting over 150 vaccination events during high-risk periods, including holidays (47). However, our results suggest that these protective effects may have been short-lived since Black patients were significantly more likely to be infected than White patients in subsequent pandemic waves (48).

In this study we observed Black patients had the lowest vaccination rates compared to all other racial or ethnic groups. This finding suggests a significant vaccine hesitancy, possibly due to historical mistrust of the healthcare system (49). Misinformation about vaccine safety and efficacy may also deter individuals from getting vaccinated. Additionally, barriers such as lack of transportation, inflexible work schedules, and limited access to healthcare facilities further hinder vaccination efforts. Taken together, our results highlight the complex interplay of factors that contributed to variation in infection rates among Black, such as the emergence of new variants, public health measures, and vaccination uptake.

A major strength of this study is the large cohort size, which included different racial and ethnic groups, including MEA as well as the comprehensive analysis of infection and vaccination rates across multiple pandemic waves. However, the study has some limitations. The study is retrospective and relies on the accuracy of electronic medical records, which may have inaccuracies or missing information. Additionally, the categorization of race and ethnicity is self-reported, which may not capture the full diversity within these groups, especially for MEA and HL categories. Also, the study population was restricted to patients presenting to the emergency department, excluding individuals with milder COVID-19 symptoms remained home or sought outpatient care. As this study was conducted in Southeast Michigan, the findings may not be directly transferable to regions with distinct demographic characteristics or generalized to other regions.

In conclusion, our study highlights the significance of the racial and ethnic disparities in COVID-19 infection rates and vaccination uptake in Southeast Michigan. Hispanic and MEA individuals experienced higher infection rates across most pandemic waves, while Black individuals had a variable rate in different waves. This study emphasizes the need for further investigation into factors that affected infection rates other than vaccine uptake in these racial and ethnic groups in Southeast Michigan. Understanding these drivers is essential for designing targeted public health messaging and interventions. For future epidemics or pandemics, especially in Michigan, it is important to strengthen community partnerships and engage trusted local organizations, such as Black churches early in the response. Broader efforts should include collecting real-time, disaggregated data by race, ethnicity, geography, and socioeconomic status to guide equitable interventions. Also, expanding access to care, ensuring equitable distribution of testing, treatment, and vaccines. Moreover, a social determinant of health and improving vaccine outreach are crucial steps towards reducing these disparities and improving health outcomes in vulnerable populations.