SARS-CoV-2 Antibody Prevalence and Association with Routine Laboratory Values in a Life Insurance Applicant Population

Rigatti, S. J.; Stout, R.

Objectives: The prevalence of SARS-CoV-2 antibodies in the general population is largely unknown. Since many infections, even among the elderly and other vulnerable populations, are asymptomatic, the prevalence of antibodies could help determine how far along the path to herd immunity the general population has progressed. Also, in order to clarify the clinical manifestations of current or recent past COVID-19 illness, it may be useful to determine if there are any common alterations in routine clinical laboratory values. Methods: We performed SARS-CoV-2 antibody tests on 50,130 consecutive life insurance applicants who were having blood drawn for the purpose of underwriting (life risk assessment). Subjects were also tested for lipids, liver function tests, renal function studies, as well as serum proteins. Other variables included height, weight, blood pressure at the time of the blood draw, and history of common chronic diseases (hypertension, heart disease, diabetes, and cancer). Results: The overall prevalence of SARS-CoV-2 was 3.0%, and was fairly consistent across the age range and similar in males and females. Several of the routine laboratory tests obtained were significantly different in antibody-positive vs. antibody-negative subjects, including albumin, globulins, bilirubin, and the urine albumin:creatinine ratio. The BMI was also significantly higher in the antibody-positive group. Geographical distribution revealed a very high level of positivity in the state of New York compared to all other areas (17.1%). Using state population data from the US Census, it is estimated that this level of seropositivity would correspond to 6.98 million (99% CI: 6.56-7.38 million) SARS-CoV-2 infections in the US, which is 3.8 times the cumulative number of cases in the US reported to the CDC as of June 1, 2020. Conclusions: The estimated number of total SARS-CoV-2 infections based on positive serology is substantially higher than the total number of cases reported to the CDC. Certain laboratory values, particularly serum protein levels, are associated with positive serology, though these associations are not likely to be clinically meaningful.