Seven-Month Analysis of Five SARS-CoV-2 Antibody Assay Results after ChAdOx1 nCoV-19 Vaccination: Significant Decrease in SARS-CoV-2 Antibody Titer

Abstract

We investigated the longevity rates of antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) after a complete ChAdOx1 nCoV-19 vaccination, which are rare and important to estimate their efficacy and establish a vaccination strategy. We assessed the positivity rates and changes of titers before (T0) and at one month (T1), four months (T2), and seven months (T3) after a ChAdOx1 nCoV-19 vaccination using five SARS-CoV-2 antibody assays. A total of 874 serum samples were obtained from 228 (T0 and T1), 218 (T2), and 200 (T3) healthcare workers. The positive rates for all five assays were 0.0–0.9% at T0, 66.2–92.5% at T1, 98.2–100.0% at T2, and 66.0–100.0% at T3. The positive rates at T3 were decreased compared to those at T2. The median antibody titers of all the assays at T3 were significantly decreased compared to those at T2 (860.5 to 232.0 U/mL for Roche total, 1041.5 to 325.5 AU/mL for Abbott IgG, 10.9 to 2.3 index for Siemens IgG, 99.5% to 94.7% for SD Biosensor V1, and 88.5% to 38.2% for GenScript). A third-dose scheme can be considered based on our data generated from five representative assays. Our findings contribute insights into SARS-CoV-2 antibody assays and appropriate vaccination strategies.

Hirayama Disease Diagnosed after COVID-19 mRNA Vaccination in an Adolescent Patient: A Case Report

“…In addition, in a blood test conducted on December 31 to differentiate other diseases that cause muscle weakness, such as GBS, Miller Fisher syndrome, and neuromyelitis optica, negative results were obtained for anti-GM1 immunoglobulin G (IgG) isotype, anti-GD1B IgG isotype, anti-GQ1b IgG, and anti-aquaporin 4 IgG. In the COVID-19 antibody assays, the Roche total antibody value was 201 U/mL and the Abbott IgG value was 4,621 AU/mL, 7.5 times higher than the maximum Roche antibody value (26.7 U/mL) measured 1 month after vaccination and 6.3 times higher than the maximum Abbott IgG antibody value (732.8 AU/mL) [5]. In short, the increase in the antibody load after the COVID-19 vaccination was abnormally high.…”