**Socio-Economic Determinants of SARS-CoV-2 Infection: Results from a Population-Based Serosurvey in Geneva, Switzerland**

**Hugo-Alejandro Santa-Ramírez1,5, Ania Wisniak1,2, Nick Pullen1 , María-Eugenia Zaballa1 , Francesco Pennacchio1 , Elsa Lorthe1 , Hélène Baysson1 , Idris Guessous1,3, and Silvia Stringhini1,3,4** <sup>1</sup> Unit of Population Epidemiology, Geneva University Hospitals, Geneva, Switzerland; <sup>2</sup> Institute of Global Health, Faculty of Medicine, University of Geneva, Geneva, Switzerland; <sup>3</sup> Department of Health and Community Medicine, Faculty of Medicine, Geneva, Switzerland; 4University Centre for General Medicine and Public Health (UNISANTE), University of Lausanne, Lausanne, Switzerland; <sup>5</sup> National Faculty of Public Health, University of Antioquia, Medellin, Colombia

SARS-CoV-2 infection and its health consequences have disproportionally affected disadvantaged socioeconomic groups globally. However, most evidence relies on confirmed cases. Serological surveys are useful as they yield more accurate estimations of the real number of infections, including mild and asymptomatic cases. This study aimed to analyze the association between socio-economic conditions and having developed anti-SARS-CoV-2 antibodies in a population-based sample in the canton of Geneva, Switzerland. Data were obtained from a population-based serosurvey of adults in Geneva and their household members, between November and December 2020, towards the end of the second pandemic wave in the canton. We tested participants for anti-SARS-CoV-2 antibodies targeting the spike (S) protein. Socio-economic conditions were self-reported and included occupational position, education, family income, ethnicity, country of birth, household residential area, household density, and the experience of financial hardship. Mixed effects logistic regressions were conducted for each predictor to test its association with the seropositive status as the main outcome. A total of 2,889 adults completed the study questionnaire and were included in the final analysis. Retired participants and those living in suburban areas had lower odds of a seropositive result when compared to employed participants or those living in urban areas, respectively. People facing financial hardship for less than one year had higher odds of a seropositive result compared to those who had never faced financial difficulties. Education, occupation, and income were not associated with seropositive status to SARS-CoV-2, nor were ethnicity or country of birth in the overall study sample. Employment status, the experience of financial hardship, and residential areas were associated with the development of anti-SARS-CoV-2 antibodies following infection during the second wave of the pandemic. Although no association was found with traditional measures of socioeconomic status in our sample, inequalities in SARS-CoV-2 infection were apparent across other socioeconomic conditions, calling for attention to the broader set of determinants of health that may shape a differential distribution of COVID-19 within the population. This is imperative for tailoring public health interventions, such as vaccine prioritization and public health campaigns, and for setting up supportive mechanisms for vulnerable population groups.

Hugo-Alejandro Santa-Ramírez1,5, Ania Wisniak 1,2, Nick Pullen1, María-Eugenia Zaballa1, Francesco Pennacchio1, Elsa Lorthe1, Hélène Baysson1, Idris Guessous1,3, and Silvia Stringhini1,3,4

1 Unit of Population Epidemiology, Geneva University Hospitals, Geneva, Switzerland

2 Institute of Global Health, Faculty of Medicine, University of Geneva, Geneva, Switzerland

<sup>3</sup> Department of Health and Community Medicine, Faculty of Medicine, Geneva, Switzerland

4 University Centre for General Medicine and Public Health (UNISANTE), University of Lausanne, Lausanne, Switzerland

5 National Faculty of Public Health, University of Antioquia, Medellin, Colombia

#### Background

SARS-COV-2infection and its health-related consequences have disproportionally affected disadvantaged socio-economic groups (1–3). Disadvantaged populations accumulate several vulnerabilities to infection, such as poor living conditions, higher job instability, fewer job opportunities, poorer social benefits and lower financial security (4,5). They are also known to have a higher burden of chronic diseases and reduced access to healthcare (6), both risk factors for COVID-19 severity (7). Several studies revealing social inequalities related to COVID-19 have been based on confirmed RT- PCR test results, therefore missing a large part of the population who did not undergo testing (8,9). A better picture of the distribution of the infection in the population can be achieved with serological surveys (10). Understanding the influence of socioeconomic conditions on the probability of being infected with SARS-CoV-2 is crucial for the implementation of equity-driven public health measures to contain the spread of the virus

Aim: To analyze the association between socio-economic conditions and having developed anti-SARS-CoV-2 antibodies during the second COVID-19 wave in a representative sample of the population in the canton of Geneva.

#### Results

In total, 2,889 participants had a blood sample taken, completed the study questionnaire and were included in the final analysis. Education, occupation and income were not associated with being seropositive in the overall sample (results not shown). Associations were found with employment status, financial hardship and the residential area in the overall sample, with retired people and those living in a suburban area exhibiting lower odds of a seropositive result when compared with those employed and those living in an urban area, respectively. People facing financial hardship for less than a year had twice the odds of a seropositive result when compared to those that had never faced financial difficulties, with all other variables remaining constant. This association did not hold for participants having faced financial difficulties for several years. People living in households with higher density also tended to have higher odds of a seropositive result. Ethnicity and country of birth were not associated with seropositivity in our sample (see table).

#### OR 2.23

People facing financial hardship in the last year had 2.23 times the odds of a seropositive result compared to those who never faced financial difficulties.

OR 0.42

#### Retirees had 0.42 times the odds of a seropositive result compared to those employed.

#### OR 0.67

People living in suburban areas had 0.67 times the odds of a seropositive result compared to those living in urban areas.


#### Conclusions

The COVID-19 pandemic has disproportionately affected socially vulnerable populations globally. However, the impact of socio-economic determinants can vary widely depending on geographical, political and cultural contexts (11–13). In our study, we have found associations of employment status, financial hardship and residential area with the natural development of anti SARS-CoV-2 antibodies during the second wave of the pandemic (before the roll-out of the vaccination campaign in Switzerland), but not with other socioeconomic conditions. Our results highlight the importance of examining the broader social determinants of health when evaluating the differential impact of the pandemic within the population and when setting up public health interventions and supportive mechanisms for vulnerable population groups.

#### References

