Comparison of Kinetics of Antibody Avidity and IgG Subclasses' Response in Patients with COVID-19 and Healthy Individuals Vaccinated with the BNT162B2 (Comirnaty, Pfizer/BioNTech) mRNA Vaccine.

There are limited reports concerning the levels of antibodies in IgG subclasses and the avidity of IgG, which is the functional strength with which an antibody binds to an antigen in serum samples obtained at different times after infection or vaccination. This study investigated the kinetics of antibody avidity and the IgG antibody response within IgG1-IgG4 subclasses in individuals vaccinated with the BNT162B2 mRNA vaccine and in COVID-19 patients. Serum samples were collected from individuals vaccinated with three doses of the BNT162B2 (Comirnaty, Pfizer/BioNTech) vaccine and from unvaccinated COVID-19 patients. This study revealed that IgG1 was a dominating subclass of IgG both in COVID-19 patients and in vaccinated individuals. The level of IgG4 and IgG avidity significantly increased 7 months after the first two doses of the vaccine and then again after the third dose. IgG2 and IgG3 levels were low in most individuals. Investigating IgG avidity and the dynamics of IgG subclasses is essential for understanding the mechanisms of protection against viral infections, including COVID-19, especially in the context of immunization with innovative mRNA vaccines and the possible future development and application of mRNA technology.

Detection of SARS-CoV-2 Using Reverse Transcription Helicase Dependent Amplification and Reverse Transcription Loop-Mediated Amplification Combined with Lateral Flow Assay.

Rapid and accurate detection and identification of pathogens in clinical samples is essential for all infection diseases. However, in the case of epidemics, it plays a key role not only in the implementation of effective therapy but also in limiting the spread of the epidemic. In this study, we present the application of two nucleic acid isothermal amplification methods-reverse transcription helicase dependent amplification (RT-HDA) and reverse transcription loop-mediated amplification (RT-LAMP)-combined with lateral flow assay as the tools for the rapid detection of SARS-CoV-2, the etiological agent of COVID-19, which caused the ongoing global pandemic. In order to optimize the RT-had, the LOD was 3 genome copies per reaction for amplification conducted for 10-20 min, whereas for RT-LAMP, the LOD was 30-300 genome copies per reaction for a reaction conducted for 40 min. No false-positive results were detected for RT-HDA conducted for 10 to 90 min, but false-positive results occurred when RT-LAMP was conducted for longer than 40 min. We concluded that RT-HDA combined with LFA is more sensitive than RT-LAMP, and it is a good alternative for the development of point-of-care tests for SARS-CoV-2 detection as this method is simple, inexpensive, practical, and does not require qualified personnel to perform the test and interpret its results.

Comparison of anti-SARS-CoV-2 IgG and IgA antibody responses post complete vaccination, 7 months later and after 3rd dose of the BNT162b2 vaccine in healthy adults.

BACKGROUND: The mRNA Covid-19 vaccine (BNT162b2) is administered in two doses with 21 days interval. On 4th October 2021 European Medicines Agency approved administration of a booster dose in at least 6 months after the second dose for people aged 18 years and older. OBJECTIVES: In the present study we compare the anti-SARS-COV-2 IgG and IgA antibody responses post complete vaccination, 7 months later and after the 3rd (booster) dose of the BNT162B2 vaccine in healthy adults. STUDY DESIGN: The levels of vaccine IgG and IgA antibodies to SARS-CoV-2 were assessed in serum samples obtained from individuals vaccinated with two doses and a booster of BNT162b2 vaccine. Samples were tested using the SARS-CoV-2 receptor-binding domain (RCB) IgG and IgA semi-quantitative commercial ELISA assay. RESULTS: The geometric mean of the anti-SARS-COV-2 IgG and IgA antibody level 7 months after vaccination of 90 healthy adults with BNT162B2 vaccine decreased significantly from 12.0 to 5.4 and 5.6 to 2.3, respectively. After the third dose of the same vaccine, the antibody level increased again, to values higher than at the beginning after the second dose. CONCLUSIONS: Significant decrease of antibody levels within a few months after full vaccination could result in the higher risk of SARS-CoV-2 infection, especially when new variants of the virus emerge. The booster could be crucial for protection against new SARS-CoV-2 variants. The antibody level seems to decrease slower in vaccinated individuals with history of COVID-19 and in younger individuals.

The level of protective post-vaccination antibodies in NIPH-NIH employees after administration of Pfizer vaccine against COVID-19.

INTRODUCTION: The new SARS-CoV-2 coronavirus, first recognized in China in 2019, within a few months caused a global pandemic of a disease called COVID-19. The high incidence and mortality of COVID-19 was the reason for the beginning of intensive work on the development of an effective vaccine. In Poland, mass vaccinations against this disease began at the end of December 2020. OBJECTIVES: The aim of the presented study was to determine the effectiveness of stimulating the production of specific antibodies for SARS-CoV-2 by the Pfizer vaccine. MATERIAL AND METHODS: The presence of IgA and IgG antibodies to the spike (S protein) of SARSCoV-2 was tested by the ELISA/Euroimmun in serum samples obtained from 140 the employees of NIPH-NIH (137 were vaccinated). In addition, the presence of IgG antibodies to S protein, nucleoprotein, and mixture of both in selected serum samples was tested by the newly developed in NIPH-NIH in-house ELISA assay. RESULTS: IgA and IgG antibodies to the S protein of the SARS-CoV-2 were detected by ELISA/Euroimmun, respectively in 136 and in all 137 vaccinated persons. There were no statistically significant differences in the level of antibodies depending on the sex and age of the vaccinated persons. Slightly higher levels of antibodies have been demonstrated in vaccinated subjects with documented preexisting SARS-CoV-2 immunity compared to subjects without COVID-19 history. The presence of IgA and IgG antibodies was found in respectively, 18 (45.0%) and all 40 (100.0%) tested vaccinated persons by the in-house ELISA with mixture antigen. The study showed that ELISA assay with N protein as an antigen may enable the distinction between antibodies acquired after infection and after vaccination. CONCLUSIONS: The results obtained in the presented study clearly demonstrate the high effectiveness of the Pfizer vaccine in stimulation of the human immune system to produce antibodies specific for the S protein of the SARS-CoV-2. It is necessary to continue testing vaccine antibody levels at various times after vaccination to determine the potential duration of humoral immunity.

Characteristics and assessment of the usefulness of serological tests in the diagnostic of infections caused by coronavirus SARS-CoV-2 on the basis of available manufacturer's data and literature review.

Recognized in 2019 in Wuhan, China, the new SARS-CoV-2 coronavirus is responsible for the occurrence of a global pandemic disease called COVID-19. So far, confirmation of infection is based on the detection of virus RNA in a sample taken from a person meeting the suspected case definition. However, in the laboratory diagnosis of SARS-CoV-2 infections, in addition to genetic tests, serological methods can also be used to detect specific antibodies of the IgM, IgG and IgA class produced after contact with antigens or to detect viral antigen. Currently, a number of rapid immunochromatographic, chemiluminescent and ELISA immunoassay tests developed by different manufacturers for the diagnosis of COVID-19 are available on the market. Despite this fact, so far there is no WHO or ECDC recommendations or even reliable research regarding the usefulness of serological investigations in the laboratory diagnosis of infections caused by SARS-CoV-2.