Pre-infection antibody levels of vaccinated healthcare workers with SARS-CoV-2 breakthrough infection: A nested case-control study.

AIM: To evaluate anti-RBD IgG antibody levels and neutralizing antibody titers between the health care workers (HCWs) with breakthrough SARS-CoV-2 infection and controls. METHODS: In this nested case-case control study, we followed 548 vaccinated HCWs with homologous (only with inactivated vaccine) or heterologous (both with inactivated and BNT162b2 vaccine) vaccination for 11 months, prospectively. We obtained blood samples from the participants for quantitative anti-RBD IgG and surrogate neutralization test. The participants with SARS-CoV-2 PCR positivity (at least 14 days after the last vaccination) were considered breakthrough infection. We chose 1:2 matched controls from the cohort, according to age, sex and vaccination status. We used R version 4.0.2 for the statistical analysis. RESULTS: Sixty-five cases and 130 controls were included in the study. The number of the breakthrough infections in HCWs were correlated with the pandemic waves in Türkiye and peaked during Omicron outbreak. The median age of the cases was 39 and 78.5% were female. The cases had more comorbidities than controls, significantly (p = 0.021). All cases experienced no or mild symptoms and recovered completely. Both pre-infection anti-RBD antibody and neutralizing antibody titers did not differ between cases and matched controls (p = 0.767, p = 0.628). CONCLUSION: In this study, we showed that there was no comparable difference in humoral response after homologous or heterologous vaccination between the cases of breakthrough infection and matched controls. Compliance with infection control measures should be ensured, in combination with vaccination.

An analysis of antibody response following the second dose of CoronaVac and humoral response after booster dose with BNT162b2 or CoronaVac among healthcare workers in Turkey.

Limited data are available on the short- to midterm levels of antibodies to the CoronaVac vaccine and quantitative change in humoral response after homologous or heterologous booster doses. In this prospective cohort study, we evaluated the anti-receptor-binding domain (RBD) immunoglobulin G (IgG) levels after two doses of CoronaVac and heterologous/homologous booster administration among healthcare workers in a university hospital in Turkey. Quantitative anti-RBD IgG antibody levels were measured at first and fourth months in 560 healthcare workers who had completed two doses of CoronaVac vaccine, and within 2 months after the third dose of CoronaVac or BNT162b2. Participants were asked to complete a questionnaire during the first blood draw. The seropositivity rate was 98.9% and 89.1%, and the median antibody level was 469.2 AU/ml and 166.5 AU/ml at first and fourth month, respectively. In the fourth month, a mean reduction of 61.4% ± 20% in antibody levels was observed in 79.8% of the participants. The presence of chronic disease (odds ratio [OR]: 1.76, 95% confidence interval [CI]: 1.15-2.69) and being in the 36-50 age group (OR: 2.11, 95% CI: 1.39-3.19) were identified as independent predictors for low antibody response. The antibody level increased 104.8-fold (median: 17 609.4 vs. 168 AU/ml) and 8.7-fold (median: 1237.9 vs. 141.4 AU/ml) in the participants who received BNT162b2 and CoronaVac, respectively. During the follow-up, 25 healthcare workers (4.5%) were infected with severe acute respiratory syndrome coronavirus 2. Considering the waning immunity and circulating variants, a single booster dose of messenger RNA vaccine seems reasonable after the inactivated vaccine especially in risk groups.

Evaluation of COVID-19 antibody response with using three different tests.

BACKGROUND AND OBJECTIVES: In this study, the performance of three different commercial antibody assays for COVID-19 was examined and parameters affecting the antibody response were investigated. The correlation of patients' chest CT results, procalcitonin, CRP, and D-dimer levels with the antibody response were retrospectively evaluated. MATERIALS AND METHODS: COVID-19 antibodies were detected by three commercially available assays in each patient. Two of the assays were rapid immunochromatographic tests and - one was an ELISA-based IgG assay. SARS-CoV-2 RNA was tested by "COVID-19 RT-qPCR Detection Kit" using nasopharyngeal swab samples. The results of antibody tests were compared with each other, RT-qPCR, Biochemical parameters and chest CT findings. RESULTS: RT-qPCR was positive in 46.6% (41/88) of the evaluated patients among which 77.3% (68/88) were healthcare workers. Seventeen (41.4%) of viral RNA positive patients had a positive antibody result with at least two assays. Both of the rapid immunochromatographic tests had identical sensitivity of 36.6% and specificity of 100%, compared to RT-qPCR assay; while the sensitivity of the ELISA based Euroimmune test was 43.9%, and the specificity was 95.7%. The sensitivity and specificity of the immunochromatographic tests were 75% and 100% respectively, compared to ELISA test result. There was a correlation between antibody positivity and old age and male gender. The presence of typical chest CT findings increased the antibody positivity 13.62 times. Antibody positivity was also increased with the decrease in Ct value of the PCR assay. There was no significant relationship between the biochemical parameters (CRP, D-dimer and procalcitonin values) and the antibody or RT-qPCR results. CONCLUSION: There was a correlation between antibody response and male gender, older age, presence of symptoms, typical chest CT findings and low PCR-Ct value.

Clinical and radiological diagnosis of non-SARS-CoV-2 viruses in the era of COVID-19 pandemic.

Following the announcement of the first coronavirus disease 2019 (COVID-19) case on 11 March 2020 in Turkey, we aimed to report the coinfection rates, and the clinical, laboratory, radiological distinctive features of viral pneumonia caused by viruses other than severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). A cross-sectional study was conducted between 18 and 31 March 2020. COVID-19 suspected cases admitted to pandemic policlinic, who had nasopharyngeal swab specimens tested for both SARS-CoV-2 and other respiratory viral pathogens, were included. Among 112 patients, SARS-CoV-2 was detected in 34 patients (30%). Among the non-SARS-CoV-2 viruses (n = 25, 22%), metapneumovirus (n = 10) was the most frequent agent. There were two coinfections with SARS-CoV-2. Sputum was less in the SARS-CoV-2 group (P = .003). The leukocyte, lymphocyte, and thrombocyte count and C-reactive protein levels were the lowest in the SARS-CoV-2 group (P < .001, P = .04, P < .001, P = .007, respectively). Peripheral involvement (80% vs 20%; P ≤ .001), pure ground-glass opacity (65% vs 33%; P = .04), apicobasal gradient (60% vs 40%; P = .08), involvement of greater than or equal to three lobes (80% vs 40%; odds ratio: 6.0; 95% confidence interval: 1.33-27.05; P = .02), and consolidation with accompanying ground-glass opacity (4% vs 33%; P = .031) were more common in SARS-CoV-2 group. Some clinical, laboratory, and radiological findings may help in the differential diagnosis of non-SARS-CoV-2 viruses from COVID-19. However, coinfections may occur, and a non-SARS-CoV-2 pathogen positivity does not exclude accompanying COVID-19.