Investigation of SARS-CoV-2-Specific Humoral and Cellular Immunity Values in Health Care Workers with COVID-19 Disease and Administered with COVID-19 Vaccine

Abstract

For limiting the coronavirus disease-2019 (COVID-19) pandemic, the effects on both humoral and cellular immune responses due to vaccines and previous infection should be taken into consideration. In some of the studies about the humoral immune response of the virus and different vaccines, it has been suggested that there can be a discordance between cellular and humoral immune responses during COVID-19 infection. The aim of this study was to determine the effects of humoral and cellular immune responses against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) antigens in three groups of healthcare workers (HCWs) who were vaccinated with two doses of inactivated virus vaccine (CoronaVac), non-vaccinated and recovered COVID-19 infection and non-infected healthy controls by comparing the variables of gender and age and to examine the relationships between them. In this study, the antibody recognizing the receptor binding domain (RBD) of the spike (S) glycoprotein (IgG-S), nucleocapsid protein (IgG-N) of SARS CoV-2 and Interferon Gamma (IFN-γ) titres were determined among non-infected and vaccinated with two doses of inactivated virus vaccine (IVV) (n= 56, 1st group: 27 men, 29 women), non-vaccinated and COVID-19 convalescents (CG) (n= 41; 2nd group: 21 men, 20 women) and non-vaccinated and non-infected healthy controls (HCG) (n= 23, 3rd group: 10 men, 13 women) in 120 HCWs. Diagnosis of all the participants in COVID-19 CG was confirmed for SARS CoV2 infection with reverse transcription polymerase chain reaction (RT-PCR) test according to manufacturer's instruction (Bio-speedy® SARS CoV-2 Double Gene RT-qPCR, Bioeksen R and D Technologies, Turkey). IgG-S and IgG-N antibody levels were determined quantitatively by Abbott Architect i2000 (Abbott Laboratories, Abbott Park, IL, USA) system. (Qiagen, MD, USA). IFN-γ levels were determined by using the QuantiFERON SARS-CoV-2 Starter Blood Collection Tubes (Qiagen, MD, USA). All statistical data analysis were conducted using SPSS (version 22, IBM Corp., Armonk, NY, USA). Student's independent t-test or Mann-Whitney U test was used for the differences between bivariate groups and Spearman Rank correlation was used to evaluate the monotonic relationship between nonnormally distributed data sets. Spearman rho > 0.7 denotes high, 0.7 > rho > 0.5 moderate and rho > 0.05 was considered as significant. For each of the immunity parameters, there were no significant differences between males and females in the IVV group, as well as in the CG. In neither of the groups age and immunity parameters were found to be highly correlated. All three immunity parameters of males in CG and IVV groups significantly differed from each other. Although humoral immunity parameters of females between CG and IVV groups did not show any significant difference, the IFN-γ titres significantly differed from each other. There were no significant differences in the IgG-S titres between CG and IVV combined gender groups. However, IgG-N and IFN-γ titres significantly differed from each other between CG and IVV groups. Antibody and particularly IFN-γ levels in two dose CoronaVac vaccinated group were less pronounced in comparison to the observed responses in COVID-19 convalescents group, indicating that CoronaVac may induce substantially less robust and persistent cellular and humoral responses than natural SARS-CoV-2 infection.