COVID-19 has resulted in enormous morbidity and mortality around the world. The pandemic has also adversely affected socially susceptible individuals with lower levels of education, lower yearly household income, and a higher percentage of pediatric family members.
Vaccination is an important technique for mitigating the effects of COVID-19 and reducing the global COVID-19 burden on health and healthcare institutions.
In a recent Centers for Disease Control and Prevention's (CDC) Morbidity and Mortality Weekly Report (MMWR), researchers describe discrepancies in the incidence rates of coronavirus disease 2019 (COVID-19) and the effects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination on the inequalities by annual household income in Los Angeles.
Study: Disparities in COVID-19 Disease Incidence by Income and Vaccination Coverage — 81 Communities, Los Angeles, California, July 2020–September 2021. Image Credit: OSORIOartist / Shutterstock.com
About the study
In the present study, researchers evaluate SARS-CoV-2 infection incidence among 81 lowest-income localities in California and the effect of COVID-19 vaccination on decreasing these discrepancies.
Data on a total of 5,083,093 Los Angeles community-dwelling residents were obtained from the Los Angeles Times SARS-CoV-2 infection information repository between March 2020 and September 2021. The United States Census Bureau provided sociodemographic information. Using postal codes as the identifier, SARS-CoV-2 infection incidence rates and immunization information were linked with U.S. census information.
Generalized linear mixed effects-type modeling was performed with Poisson distributions to determine the median SARS-CoV-2 vaccination uptake in Los Angeles communities. Disease incidence rates across household income levels were determined during three periods of surges in SARS-CoV-2 infections.
Adjusted incidence rate ratio (aIRR) values were compared between areas based on the median family income percentile in the highest month of every COVID-19 wave. The covariates were adjusted by participants' sex, the proportion of prime-vaccinated individuals, the proportion of individuals aged 65 years and above, those born in non-U.S. locations, non-Hispanic Whites, Blacks, or African Americans, Hispanics, or Latinos, individuals who had attained high school-level education, the mean family count, and the number of individuals without health insurance.
Study findings
The aIRR values among localities with the smallest and biggest median family income deciles in the first two surge periods were 6.6 and 4.3, respectively. Model estimations did not reveal an incidence differential among the richest and poorest households during the September 2021 surge with an aIRR of 0.8.
Vaccination uptake was lowest among low-income communities and highest among high-income ones at 59% and 72%, respectively. A significant relationship between family income levels and COVID-19 vaccination on the incidence of SARS-CoV-2 infections revealed that vaccination had the most profound effect on SARS-CoV-2 infection incidence among low-income groups. Vaccination availability was inversely correlated with SARS-CoV-2 infection incidence across all income levels; however, this impact was greatest in low-income populations.
A 20% rise in community vaccinations would have led to an additional 8% reduction in the incidence of SARS-CoV-2 infections among communities with low incomes compared to those with high incomes. These findings highlight the importance of increasing the availability of vaccines and reducing vaccine reluctance in impoverished communities to decrease the inequalities in SARS-CoV-2 infection incidence.
Vaccination uptake was inversely related to the incidence of SARS-CoV-2 infections across all socioeconomic levels during the third COVID-19 surge period. Vaccination had the most significant influence on SARS-CoV-2 infection incidence in low-income groups, likely due to the higher likelihood of SARS-CoV-2 exposures and amounts of post-SARS-CoV-2 infection immunity.
Despite efforts by the government to improve vaccine availability for low-income localities, vaccination uptake varied by income. California assigned 40% of COVID-19 vaccinations to groups in the Californian Healthy Places Index's (HPI) lowermost quartile, which resulted in a minor variation in prime vaccination uptake among adults across different income levels in Los Angeles communities during the third surge in September 2021.
Conclusions
COVID-19 incidence was higher in lower-income communities of Los Angeles during two COVID-19 surges before vaccine availability in July 2020 and January 2021 as compared to higher-income communities.
Despite lower vaccination coverage, the effects of vaccination were highest in the low-income communities. Thus, addressing barriers to COVID-19 vaccination in lower-income communities is crucial to reducing disparities in SARS-CoV-2 infection incidence and related illnesses.
Efforts to increase vaccination confidence and accessibility are needed to reduce income-associated inequalities. Future preparation is also essential to ensure preparedness to deploy methods to reduce inequalities during pandemics that affect low-income populations while vaccines are being produced.
Minimizing vaccination challenges, such as delivering booster doses of updated bivalent SARS-CoV-2 vaccines, is critical for reducing the impact of SARS-CoV-2 infections and associated diseases in the U.S.
Journal reference:
- Masterson, J. M., Luu, M., Dallas, K. B., et al. (2023). Disparities in COVID-19 Disease Incidence by Income and Vaccination Coverage — 81 Communities, Los Angeles, California, July 2020–September 2021. MMWR Morbity Mortality Weekly Report. doi:10.15585/mmwr.mm7226a5