Comparison of SARS-COV-2 antibody assays in PCR negative and PCR positive Turkish patients

Abstract

To the editor, Serology may offer valuable information during COVID-19 pandemic however published papers mainly reported the results of symptomatic patients having positive RT-PCR on upper respiratory tract specimens [1]. More studies are needed to address whether asymptomatic patients, or patients with chest imaging compatible with COVID-19 but negative RT-PCR, have different antibody response that could influence assays performances. We wanted to share our data from Turkey where 4.323.596 COVID-19 cases were detected out of 44.087.628 PCR tests by April, 20, 2021 but there are only a couple of published studies about serodiagnosis of the infection.According to the interim guidance of WHO (Diagnostic testing for SARS-CoV-2), interpretations of serology should be made by an expert and are dependent on several factors including the timing of the disease, clinical morbidity, the epidemiology and prevalence within the setting, the type of test used, the validation method, and the reliability of the results . IDSA (Infectious Diseases of South America) guideline suggest not to use any serological test during the first 2 weeks following infection and to use IgG antibody to provide evidence of COVID-19 infection in symptomatic patients with a high clinical suspicion and repeatedly negative PCR results [2]. Commercially available serological assays for SARS-CoV-2 like ELISAs and lateral flow assays are high throughput, relatively inexpensive and use readily available instrumentation. These assays are performed with recombinant antigens, such as the spike protein (the main surface glycoprotein that is used to attach and enter cells) of SARS-CoV-2;

Highly sensitive and simultaneous detection of ctDNAs related to non-small cell lung cancer in serum using a catalytic hairpin assembly strategy in a SERS microfluidic chip

“…[32][33][34][35][36] However, PCR requires strict experimental conditions and was prone to cross contamination, resulting in false negative and false positive results. 37 LAMP, SDA, and RCA could be used for constant temperature amplification without the need for special heating equipment. However, these methods rely on the use of enzymes, and the enzyme is expensive, have a short storage time, and the enzyme activity is easily affected by complex environmental conditions, which limit its further application.…”