Understanding the Patterns of Serological Testing for COVID-19 Pre- and Post-Vaccination Rollout in Michigan.

Xu Shi,Bhramar Mukherjee,Seunggeun Lee,Lars G. Fritsche,Zhangchen Zhao,Stephen Salerno

doi:10.3390/jcm10194341

Xu Shi, Bhramar Mukherjee

Open Access

https://doi.org/10.3390/jcm10194341

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Abstract

Testing for SARS-CoV-2 antibodies is commonly used to determine prior COVID-19 infections and to gauge levels of infection- or vaccine-induced immunity. Michigan Medicine, a primary regional health center, provided an ideal setting to understand serologic testing patterns over time. Between 27 April 2020 and 3 May 2021, characteristics for 10,416 individuals presenting for SARS-CoV-2 antibody tests (10,932 tests in total) were collected. Relative to the COVID-19 vaccine roll-out date, 14 December 2020, the data were split into a pre- (8026 individuals) and post-vaccine launch (2587 individuals) period and contrasted with untested individuals to identify factors associated with tested individuals and seropositivity. Exploratory analysis of vaccine-mediated seropositivity was performed in 347 fully vaccinated individuals. Predictors of tested individuals included age, sex, smoking, neighborhood variables, and pre-existing conditions. Seropositivity in the pre-vaccine launch period was 9.2% and increased to 46.7% in the post-vaccine launch period. In the pre-vaccine launch period, seropositivity was significantly associated with age (10 year; OR = 0.80 (0.73, 0.89)), ever-smoker status (0.49 (0.35, 0.67)), respiratory disease (4.38 (3.13, 6.12)), circulatory disease (2.09 (1.48, 2.96)), liver disease (2.06 (1.11, 3.84)), non-Hispanic Black race/ethnicity (2.18 (1.33, 3.58)), and population density (1.10 (1.03, 1.18)). Except for the latter two, these associations remained statistically significant in the post-vaccine launch period. The positivity rate of fully vaccinated individual was 296/347(85.3% (81.0%, 88.8%)).

Highlights

Testing for the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)that causes coronavirus disease 2019 (COVID-19) broadly falls into two categories: (1) reverse transcription polymerase chain reaction (RT-PCR) testing for active infection and (2) immunoglobulin G or M (IgG or IgM) antibody testing for SARS-CoV-2 antibodies
We further examine the pattern of serologic testing at Michigan Medicine, the characteristics of those individuals who underwent serologic testing, and the factors associated with testing positive when compared with unmatched controls
In the pre-vaccine launch period (27 April–14 December 2020), 8026 individuals presented for 8220 SARSCoV-2 antibody tests, while in the post-vaccine launch period (14 December 2020–3 May 2021), 2587 individuals presented for 2712 SARS-CoV-2 antibody tests (Figure 1)

Summary

Introduction

That causes coronavirus disease 2019 (COVID-19) broadly falls into two categories: (1) reverse transcription polymerase chain reaction (RT-PCR) testing for active infection (i.e., diagnostic testing) and (2) immunoglobulin G or M (IgG or IgM) antibody testing for SARS-CoV-2 antibodies. While the former is crucial for identifying acute, likely contagious cases, the latter is important for determining prior infection status. Recent works have examined COVID-19 outcomes [6] and testing patterns [7] for the RT-PCR diagnostic test among a cohort of susceptible individuals presenting to Michigan Medicine, a primary regional health center providing COVID-19 care throughout the pandemic. We further examine the pattern of serologic testing at Michigan Medicine, the characteristics of those individuals who underwent serologic testing, and the factors associated with testing positive when compared with unmatched controls

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