Influenza is a preventable acute respiratory illness and has a high potential to cause serious complications, especially for at-risk populations (i.e., elderly and persons with underlying chronic disease), and is associated with high mortality and morbidity in the U.S (Nicholson, 1992). During the 2019–2020 influenza season, between 38 and 56 million people were infected, and 18 to 26 million people visited medical providers due to influenza infection in the US (Centers for Disease Control and Prevention, 2020). Also, 410,000–740,000 hospitalizations and 24,000–62,000 deaths were reported because of influenza infection (Centers for Disease Control and Prevention, 2020). The Centers for Disease Control and Prevention (CDC) recommends routine annual influenza vaccination for all people who do not have contraindications to reduce the risk of influenza, hospitalization, and death (Grohskopf et al., 2020). However, approximately only half of the US population was vaccinated during the 2019–20 influenza season (Prevention CfDCa, 2020).

Prior research from Europe suggests that socioeconomic factors can explain the likelihood of being immunized against influenza apart from the known risk factors of age and chronic illnesses (Endrich et al., 2009). A recent study found that influenza vaccination rates are relatively high among older people, people with higher education levels, people with higher incomes, and among non-Hispanic whites in the US. However, a comprehensive analysis of the role of specific social vulnerabilities for different race/ethnic communities for influenza vaccination rates has not been conducted, to our knowledge.

To address this gap, we used data from the CDC's Social Vulnerability Index (SVI), which assesses the resilience of communities against natural disasters and infectious disease outbreaks (Flanagan et al., 2011a). The SVI assists public health professionals in identifying communities that are at risk of being impacted by a public health crisis because of factors like socioeconomic status, household composition, minority status, or housing type and transportation (Centers for Disease Control and Prevention, 2018). Using SVI and data on influenza vaccination rates at the county level in the US, we evaluated the specific community-level vulnerabilities that are most predictive of influenza vaccination rates.