Socioeconomic differences in SARS-CoV-2-antigen contacts after one year of the vaccination campaign

BACKGROUND: Evidence on the SARS-CoV-2 serological status of the German population by socioeconomic position (SEP) is still limited for the vaccine era of the pandemic, but could contribute to the understanding of the unequal risks of severe COVID-19. This study aims to evaluate the socioeconomic patterns of antigen contacts through infection, vaccination or both (‘hybrid immunity’) after one year of vaccination campaign in Germany. METHODS: We used nationwide serological and self-reported data from the population-based German seroepidemiological Corona Monitoring Nationwide study (RKI-SOEP-2, November 2021-February 2022) to estimate prevalence ratios (PR) of SARS-CoV-2 infection, COVID-19 vaccination (at least one dose of vaccine), basic immunization (at least two SARS-CoV-2 antigen contacts), and three antigen contacts by education and income. Estimates were derived from Poisson regression models adjusted for age, sex, migration status, urban-rural residence, federal state and date of participation. RESULTS: Across 10,448 adult participants, low-education groups had a 1.35-fold greater risk of SARS-CoV-2 infection compared to high-education groups (95% CI 1.01-1.82, p = 0.045). COVID-19 vaccination and basic immunization decreased with lower education and income. Low-education and low-income groups were less likely to have had at least three SARS-CoV-2 antigen contacts (PR low vs. high education: 0.74, 95% CI 0.65-0.84, p < 0.001; PR low vs. high income: 0.66, 95% CI 0.57-0.77, p < 0.001) CONCLUSIONS: The results show socioeconomic inequalities in SARS-CoV-2 infections, COVID-19 vaccinations and antigen contacts, suggesting a lower level of protection against severe COVID-19 for individuals with low and medium SEP. The majority of the German population exhibits further prevention potential, which could be addressed via more targeted interventions. Future research, pandemic response and vaccination campaigns should address the specific needs and barriers of these groups. KEY MESSAGES: • Multiple antigen contacts, especially through vaccination, are less prevalent in groups with low or medium socioeconomic position. • Potential to prevent severe COVID-19 exists in the majority of the German population after one year of vaccination campaign.