Despite the disparities and inequities in coronavirus disease 2019 (COVID-19) management in the United States, there are very few studies that focus on the association between risk behaviors and individual-level infection outcomes.

Study: Impact of individual-level characteristics and transmission mitigation behaviors on SARS-CoV-2 infection and seroprevalence in a large Northern California Bay Area cohort. Image Credit: Marco Di Stefano/Shutterstock

A better understanding of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) risk factors and the impact of public health measures is only possible through the analysis of individual-level data on sociodemographic factors, transmission mitigation behavior, and SARS-CoV-2 serostatus in large, community-based cohorts.

About the study

In a pre-print study published in the medRxiv* server, the authors investigated individual-level characteristics and mitigation behaviors that contributed to SARS-CoV-2 seroprevalence, self-reported infection, and viral infection, and other outcomes in a large, population-based sample of more than 5,500 individuals from 12 East Bay cities in Northern California followed longitudinally.

Also, during three time periods from July 2020 to April 2021, the authors estimated the population-adjusted prevalence of SARS-CoV-2 outcomes and differences by demographic strata as well as the effect of transmission mitigation behavior on SARS-CoV-2 prevalence. The participants were selected using a screening phase followed by a longitudinal study phase with three rounds of data collection.

The eligibility criteria of the participants included 18 years or older individuals living within the study region, willingness to provide biospecimens and questionnaire responses, ability to read and speak English or Spanish, and having internet access and an email address. The participants provided their informed consent for the screening phase as well as for each study round. At the start of each round, the eligible participants received a kit including materials for self-collection of biospecimens, pre-paid return shipping labels, and instructions to complete an online-administered questionnaire.

The questionnaire was available in English or Spanish, addressing gender, age, race/ethnicity, income, employment, physical and mental health, as well as symptoms potentially related to COVID-19 within the previous two weeks, and SARS-CoV-2 testing outside of the study. The questionnaire also addressed behaviors that might affect the risk of SARS-CoV-2 infection including physical distancing practices, close contact with others, and mask-wearing.

SARS-CoV-2 infection was identified using quantitative reverse transcription PCR (RT-qPCR). Since COVID-19 vaccines were not available in the study region during rounds one and two, the identification of antibodies against the SARS-CoV-2 spike protein was considered evidence of SARS-CoV-2 infection. When vaccinations were widely available during round three the detection of antibodies against the NC protein was considered evidence of SARS-CoV-2 infection, while the detection of antibodies against the spike protein was considered evidence of SARS-CoV-2 infection or COVID-19 vaccination. At each study round, Bayesian multilevel regression and poststratification were used to estimate population-adjusted cumulative seroprevalence, self-reported SARS-CoV-2 viral positivity prevalence, and “probable COVID-19” prevalence.

Results

The study data revealed that the overall prevalence of SARS-CoV-2 outcomes for natural infection was low due to the high percentage of mask-wearing and other risk-mitigating behaviors among the participants. The authors observed that COVID-19 vaccination seroprevalence was lesser in non-Whites compared to Whites; non-Whites without a college degree and those from lower-income households had higher seroprevalence.

Spanish speakers had higher population-adjusted seroprevalence estimates. Moreover, it was found that Whites aged 65 or older had a much higher prevalence of antibodies against the SARS-CoV-2 spike protein than non-Whites of the same age group in Round 3, which is indicative of vaccination status. Due to the high rate of mask usage by study participants the differences between high-risk and low-risk mitigation behavior and SARS-CoV-2 prevalence were not detected.

Limitations and conclusions

The major limitation associated with the study was the under-representation of some demographics in the study sample. Males, non-Whites, individuals from lower-income households, individuals with lower education levels, homeless individuals, and those from lower socioeconomic ZIP codes were underrepresented in the sample. This may have led to the underestimation of overall SARS-CoV-2 seroprevalence and self-reported infection.

In conclusion, the study findings demonstrated that non-Whites, lower-income individuals, and individuals with lower education levels had the highest SARS-CoV-2 seroprevalence and lowest vaccination seroprevalence. This highlights the significant and persistent inequities surrounding the COVID-19 pandemic. More effective policies must be implemented to allocate more resources for high-risk communities to help overcome the social and structural barriers and address these disparities and inequities.

Mask wearing is one the most effective behaviors for controlling community spread of SARS-CoV-2 infection.”

*Important notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Written by

Susha Cheriyedath

Susha has a Bachelor of Science (B.Sc.) degree in Chemistry and Master of Science (M.Sc) degree in Biochemistry from the University of Calicut, India. She always had a keen interest in medical and health science. As part of her masters degree, she specialized in Biochemistry, with an emphasis on Microbiology, Physiology, Biotechnology, and Nutrition. In her spare time, she loves to cook up a storm in the kitchen with her super-messy baking experiments.