The Inverted U-Shaped Relationship Between Socio-Economic Status and Infections During the COVID-19 Pandemic

Area of Science:

• Public Health
• Epidemiology
• Socio-economic Determinants of Health

Background:

• The COVID-19 pandemic's societal impact requires ongoing analysis, even after the global health emergency declaration.
• Socio-economic status (SES) is a known factor associated with pandemic outcomes, but its complex, regional variations warrant further investigation.

Purpose of the Study:

• To analyze the effects and mechanisms of socio-economic status (SES) on COVID-19 infections across different SES groups.
• To reveal the dynamic relationship between SES and infection rates throughout the pandemic's distinct phases.

Main Methods:

• Analysis of COVID-19 infection data stratified by socio-economic status (SES) groups: low (LSG), lower-middle (LMSG), upper-middle (UMSG), and high (HSG).
• Examination of the relationship between SES and infection rates across four distinct pandemic phases.
• Investigation into the mediating roles of medical resources, demographics, and vaccination in the SES-infection relationship.

Main Results:

• The relationship between SES and COVID-19 infections exhibited an inverted U-shape, particularly in the initial three phases.
• Upper-middle SES groups (UMSG) showed the highest infections in Phase I. Lower-middle SES groups (LMSG) had the highest infections in Phases II and III.
• Phase IV revealed a positive correlation between SES and infection numbers (r=0.54, p<0.001), indicating a shift in the dynamic.
• Demographics significantly influenced population mobility and subsequent infections in LMSG, especially in Phase II (indirect effect=0.01, p<0.05).

Conclusions:

• Socio-economic status (SES) plays a complex, non-linear role in COVID-19 infections, mediated by factors like medical access, demographics, and vaccination rates.
• Targeted public health interventions are crucial, particularly for middle SES populations, and should consider demographic influences on disease transmission.
• Future pandemic preparedness strategies must account for the evolving relationship between SES and infectious disease spread.