RESUMO
Various clinical outcomes, reinfections, vaccination programs, and antibody responses resulted from the COVID-19 pandemic. This study investigated the time-dependent changes in SARS-CoV-2 antibody responses in infected and/or vaccinated and unvaccinated individuals and to provide insights into spike and nucleocapsid antibodies, which fluctuate during infectious and non-infectious states. This cohort study was carried out at the Ege University Faculty of Medicine hospital in Izmir (western Turkey) and the Erciyes University Faculty of Medicine hospital in Kayseri (central Turkey) between December 2021 and January 2023, which coincided with the second half of COVID-19 pandemic. The study included 100 COVID-19 PCR-positive patients and 190 healthcare workers (HCWs). Antibody levels were followed up via quantitative anti-SARS-CoV-2 spike and qualitative anti-nucleocapsid immunoassays (Elecsys™). Antibody levels declined after infection but persisted for at least 6-8 months. Individuals who had received only CoronaVac had higher anti-nucleocapsid antibody levels in the early months than those who received mixed vaccination. However, anti-spike antibodies persisted longer and at higher levels in individuals who had received mixed vaccinations. This suggests that combining two different vaccine platforms may provide a synergistic effect, resulting in more durable and broad-spectrum immunity against SARS-CoV-2. The study provides information about the vaccination and antibody status of healthcare workers in the second half of the pandemic and provides valuable insights into the dynamics of antibody responses to COVID-19 infection and vaccination.
RESUMO
Background/aim: It was aimed to evaluate the results of Rose Bengal (RB), ELISA total tests (IgM and IgG), and the Brucella Coombs gel test (BCGT), which are used as screening tests, with the combined results of a tube agglutination test (standard Wright test: SWT) and a tube agglutination test with antihuman globulin (AHG TAT). Materials and methods: Samples from 97 patients prediagnosed with brucellosis (age ≥18 years) were screened with RB, ELISA, and BCGT. SWT < 160 samples and RB-negative but ELISA- or BCGT-positive samples were tested by AHG TAT. SWT ≥ 160 or AHG TAT ≥ 160 was taken as reference. Results: Thirty-two of 56 RB-positive samples and one RB-negative but ELISA- and BCGT-positive sample were found to be ≥160 with SWT or AHG TAT. Sensitivity, specificity, accuracy, and agreement (kappa) values according to SWT ≥ 160 or AHG TAT ≥ 160 positivity were as follows, respectively: RB 96.9%, 62.5%, 74.2%, and 0.509; ELISA total 100%, 60.9%, 74.2%, and 0.515; BCGT test 97%, 70.3%, 79.4%, and 0.594. Conclusion: Sensitivities of the screening tests are similar, but positivities should be confirmed by more specific tests. Positive samples from screening tests should be tested with AHG if the SWT value is <160.
