Antibody level 2 years after Moderna vaccine

Hi Mario,

I wish I had an answer for you, but I have no idea what the 1900.00 number means. Did you get tested for both the N and S proteins antibodies? It looks that way from what you copied from the report. If so, were your results negative for both types of antibodies?

I got antibody testing a few months ago for both because I was convinced I had covid despite repeatedly testing negative on home and PCR tests. If I hadn't lost smell and taste, I wouldn't have questioned it. After the anybody testing turned out negative for the N protein, I accepted that some other pathogen caused me to lose smell and taste. I still haven't regained it completely. My S protein antibody level was borderline, which means the level wasn't high enough for antibodies to be detected and not low enough to say that they were not detected. I only had one vaccine dose over 2 years ago.

Anti‐SARS‐CoV‐2 Spike Protein (S1) BORDERLINE Anti‐SARS‐CoV‐2 15.5 RU/mL

Nucleocapsid Protein (N) NOT DETECTED

I'm not sure which unit of measure they used in your test to come up with 1900.00. I hope you get some answers because I'd be curious to know what that number means also.

Okay, I've read your inquiry. I'm a retired medical professional in the U.S. and will try to bring some clarity to interpretation of your test results as posted. Although the explanation below is clinically thick beyond reason, it provides the path to why questions such as yours arose and literally threw a wrench in the interpretation of tests by both patients and the medical community. Take your time in reviewing this data because unless you are immersed in this area of science it can become boring fairly quick. Although it may not appear to be the case, the information below was diminished to a brief synopsis to avoid the full and needless complexity of the matter.

Firstly, let me state that test response to antibody binding of the N protein is insignificant and should not be used to determine previous exposure to SARS CoV-2 because it will also respond in the instance of past exposure to other coronaviruses such as those responsible for the common cold virus, etc. In other words, it's found to be non-specific and of little value when seeking to determine past exposure.

The S protein is more determinant as a consequence of representing spike protein binding.

Next on your copied information is units of measure used, in this instance COI, abbreviation for cutoff index, a value that had been initiated by many labs and literally threw the healthcare community and patients alike into a tailspin regarding its meaning and significance. The brief history of how this COI ended up in the serological tests for SARS CoV-2 is just about as confusing as its appearance and use in the assay tests.

During the early phases of the pandemic, laboratories in Pakistan began reporting numerical COI values that were used indiscriminately and wrongly compared to other testing systems intended to be used for quantitative analysis of the antibodies developed in the persons exposed to the the SARS CoV-2 virus. This technique was used without a proper orientation towards the specificity and limitations of any given testing system. Subsequently, the different numerical COI or cutoff values which were included in the laboratory reports of the test created a very perplexing issue in how these values were to be interpreted.

A study was performed where electrochemiluminescence ECLIA and ELISA assays were used to test a range of persons that included the COI refererence values. While a weak positive but statistically significant correlation was found between numerical COI value of the ECLIA with ELISA concentrations, when the results were dispersed on scatter plot there was no significant linear relationship between ECLIA and ELISA assay. It was reasoned that because both ECLIA and ELISA testing are both similarly designed for detecting antibodies against nucleocapsid protein, any associated COI or cutoff values are not meant to describe the immunity level of individuals and should not be used for the purpose of quantitative value for antibody levels in COVID-19 patients. That was then, so to speak.

Subsequently, further studies on the use of COI resulted in correlation with quantitative analysis in terms of a lookback to previous exposure. Antibody to SARS-CoV-2 were analyzed and a base cutoff index (COI) was calculated for quantitative analysis. It was found that the positivity rate and COI increased with specific time elasped since symptom onset. As a unit of quantitative measurement, anti-SARS-CoV-2 antibodies that persisted for at least 13 weeks after symptom onset reflected a high COI. There was a significant difference in anti-SARS-CoV-2 antibody positivity rate between patients with and without symptoms as well, but not with regard to sex or disease course. A descending COI pattern at weeks 1 to 5 after symptom onset was significantly more frequent in patients who demonstrated poor prognosis. Make certain that you understand that we're talking about positive assay results and not negative ones.

So with regard to your own test results, the COI or cutoff index is established by the lab performing the assays, but is not provided in the information in your posting. In general, however, IgG antibody titers are the uniform test for measurement against the COI. For reference, among the existing Immunoglobulin antibodies IgA, IgG and IgM, IgG is the most common and predominantly responsible for defense against viruses.

So having taken a very long way around the maelstrom to address your inquiry, we finally arrive at the following response in your specific instance:

******So in answer to your question, I am assuming by your post that the lab indicated your past exposure to SARS CoV 2 to be negative. The problem in providing meaning to a result of 1900.00 is that there is no COI or units of measurement provided. In other words, I'd need to know the range of the cutoff index and units of measure used by the lab performing the assay in order to share the relative meaning of your specific result. For instance purely by example only, Negative = COI <1 and Positive = COI >1 wherein the units of measurement would potentially range from 0 to a number observed to be the highest average positive result observed in those tested. Since the lab indicated a negative result, then it lies outside the range of the cutoff index, so negative test results would at the very least have to be <1901.00. In other words, it's value is of no concern other than it lies outside the COI range and therefore, negative. There is nothing regarding the value itself that would even remotely suggest any particular consequence or concern relevant to its range either high or low from the negative COI. Don't let anxiety become a runaway train in such instances by allowing your worries to create potential risks where none exist. All responses relative to the COI in this type of assay are strictly associated with what the test is specifically measuring, Any speculation about the parameters of normal is purely anxiety-driven.

"Units of Measure COI"

SARS-CoV-2 (COVID-19) S Protein Receptor Binding Domain (RBD) Binding Antibodies

= 1900.00

Hope that helps.

Best regards