Homologous and Heterologous Covid-19 Booster Vaccinations Against SARS-CoV-2 Infection in the Elderly.

A third booster doses for the 2019 coronavirus disease (COVID-19) is widely used all over the world, especially in risky individuals, with the recommendation of WHO. The purpose of this study was to evaluate the effectiveness of mRNA (BNT162b2), and CoronaVac (Sinovac Biotech) vaccines as a reminder dose following two doses of CoronaVac against COVID-19 infection, serious illness, and mortality in the geriatric population aged 75 and older during the delta variant dominant period. Our study comprised 2730 individuals the age of 75 and older in total, of which 1082 (39.6%) were male and 1648 (60.4%) were female. The vaccine effectiveness (VE) of 2 doses of CoronaVac + 1 dose of BNT162b2 vaccine combination against COVID-19 was determined as 89.2% (95% Confidence interval (CI) 80.7-93.9%), while the VE of 3 doses of CoronaVac vaccine was determined as 80.4% (95% CI 60.5-90.2%). Geriatric patients who received three doses of CoronaVac vaccine did not need intensive care. No deaths were observed in the vaccinated groups. While the VE of vaccination with 2 doses of CoronaVac + 1 dose of BNT162b2 was 41.8% (95% CI 0-74.1%) against hospitalization, 64.4% (95% CI 0-94.7%) against intensive care unit admission, the VE of vaccination with three doses of the CoronaVac was 78.2% (95% CI 0-96.5%) against hospitalization. In conclusion, our research showed that, even with the emergence of viral variants, a third dose of the CoronaVac and BNT162b2 vaccines is highly effective against symptomatic SARS-CoV-2 infection. Third-dose vaccination regimens, including heterologous and homologous vaccines, can be an effective tool in controlling the COVID-19 pandemic and the emergence of new variants.

Effectiveness of Inactivated and mRNA COVID-19 Vaccines Against SARS-CoV-2 Infection, Severe Disease and Mortality in the Geriatric Population.

Older age (>60 years) has been identified as the main risk factor for COVID-19. In this study, we aimed to evaluate the efficacy of Pfizer-BioNTech and CoronaVac vaccines against COVID-19 infection, serious illness, and mortality in the geriatric population. We found that 2 doses of CoronaVac vaccine were ineffective in protecting against COVID-19 infection in people over 65 years of age, while the vaccine efficacy (VE) of the mRNA vaccine against COVID-19 was 80% (95% CI 70-87). The VE of full vaccination with BioNTech was 89% (95% CI 53-97) against hospitalization, 79% (95% CI 0-97) against death, and 79% (95% CI 0-97) against intensive care unit (ICU) admission. However, the VE of full vaccination with CoronaVac was 50% (95% CI 33-63) against hospitalization, 53% (95% CI 26-70) against ICU admission, and 56% (95% CI 30-73) against death. In conclusion, we found that the mRNA vaccine has higher efficacy against severe COVID-19 infection and mortality in the geriatric population than the inactivated vaccine. Booster doses of vaccines should be considered in increasing the effectiveness of inactivated vaccines. Given the potential of SARS-CoV-2 mutations evading vaccination protection and the risk of reduced immunity over time, regular monitoring of vaccine effectiveness in the real world is critical.

Risks of catching COVID-19 according to vaccination status of healthcare workers during the SARS-CoV-2 Delta variant dominant period and their clinical characteristics.

The exposure of healthcare workers (HCWs) to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has been a major concern since the beginning of the coronavirus disease 2019 (COVID-19) pandemic. The study aimed to investigate the relationship between vaccination status and the status of catching COVID-19 in HCWs working in a Training and Research Hospital in Turkey, and the clinical course of the disease in those who were caught. The vaccination status of 1279 HCWs working at Siirt Training and Research Hospital during the period when the SARS-CoV-2 Delta variant was dominant, their cases of catching COVID-19 during this period, and the clinical course of the disease in patients with COVID-19 were investigated retrospectively.  We found that the rate of COVID-19 transmission was lowest in fully vaccinated HCWs (p < 0.05). The rate of COVID-19 transmission in HCWs who received two doses of BioNTech vaccine (4.4%) and two doses of CoronaVac+ one dose of BioNTech vaccines (2.7%) was considerably lower than those without vaccination (26.2%) (p < 0.05). The transmission rate was lowest among those vaccinated with two doses of CoronaVac+ one dose of BioNTech. Hospitalization was not required in fully vaccinated HCWs. The lymphocyte count was found to be significantly higher in fully vaccinated patients than incompletely vaccinated and unvaccinated patients. Although C-reactive protein (CRP), d-dimer, and ferritin values were higher in unvaccinated and partially vaccinated patients than in fully vaccinated patients, the differences were not statistically significant. As a result, the transmission rate of COVID-19 was lowest in fully vaccinated HCWs and in those vaccinated with two doses of CoronaVac+ one dose of BioNTech. In fully vaccinated HCWs, hospitalization was not needed.

Association of viral load with age, gender, disease severity, and death in severe acute respiratory syndrome coronavirus 2 variants.

In this study, the relationship between viral load, demographic characteristics, and disease information in 1007 (48.5%) patients with Delta variant (B.1.617.2), and 1070 (51.5%) patients with Alpha variant (B1.1.7) were investigated. We found that there was a significant difference in viral load between patients who died from the Alpha variant and those who were discharged (p < 0.05). Nevertheless, no significant difference was observed in patients with the Delta variant. The viral load in patients who died from the Alpha variant was significantly higher than those who were discharged (p < 0.05). The viral load was found to be higher in females in patients with the Delta variant, whereas it was very close in males and females in patients with the Alpha variant (p > 0.05). No significant difference was detected between the cycle threshold values (Ct) and disease severity. In terms of the mean Ct values, statistical differences were observed in patients with Delta and Alpha variants. The Alpha variant was found to have a higher viral load than the Delta variant. Furthermore, the Delta variant was found to be higher in the 40-year-old and under-age group than the Alpha variant, whereas the Alpha variant was higher in the groups over 40 years old. Although the rate of moderate and severe patients in the Alpha variant was found to be higher, the rate of mild survivors was found to be higher in the Delta variant. In conclusion, the increase in vaccination before the appearance of the Delta variant in our region may have influenced the viral load and clinical status of the patients.

[Direct identification and determination of antimicrobial susceptibility of gram negative bacilli using the PhoenixTM FX system in blood cultures flagging positive]. / Gram negatif basillerin PhoenixTM FX sistemi ile pozitif sinyal veren kan kültürü siselerinden direkt tanimlanmasi ve antimikrobiyal duyarliliklarinin belirlenmesi.

Bloodstream infections are one of the main causes of morbidity and mortality worldwide. Shortening the turnover time of microbiological analysis leads to a significant reduction of patient morbidity, mortality and medical care expenses. This study aimed to evaluate the performance of Phoenix 100 Instrument (Becton Dickinson, Sparks, MD, USA) system in bacterial identification and the evaluation of antibiotic susceptibility directly taken from positive blood culture bottles in BD BACTEC™ FX (Becton Dickinson, USA) system in patients with the suspicion of bacterial sepsis. In this study, blood culture bottles with a positive signal in BD BACTEC™ FX (Becton Dickinson, USA) system, and in which gram negative bacilli or coccobacilli was observed in Gram staining were evaluated. In our study, direct inoculation to the Phoenix panel from the blood culture bottles giving positive signal was defined as "direct Phoenix method". The blood culture bottles which were taken from hospitalized patients with a suspicion of sepsis, were analyzed comparatively by using BD Phoenix™ (Becton Dickinson, USA) automated microbiology system and "Bruker Biotyper matrix-associated laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS)" (Bruker Daltonics, Germany) in the bottles of patients with the positive signals between August 10, 2015, and December 05, 2015. The effect of the "direct Phoenix method" on the duration of the test and the harmony with conventional methods was demonstrated. A total of 122 gram negative bacteria comprising 95 bacteria in Enterobacteriaceae family, 26 non-fermenting gram negative bacteria (NFGNB) and one Aeromonas spp. were included in the study. In our study, the reporting time of the identification of gram negative bacteria after inoculation with direct Phoenix method ranged from 2.25 hours to 7.84 hours (mean 2.56 hours). When the identification of 122 gram negative bacteria by direct Phoenix method was compared with the identification of Maldi Biotyper (Bruker Daltonics, Germany), an agreement was detected in 96.7% (118/122) of the samples at the genus level and in 86.0% (105/122) of the samples at the species level. Ninety-five bacteria belonging to Enterobacteriaceae family demonstrated an agreement of 95.7% (91/95) and 93.6% (89/95) at the genus and species levels with Maldi Biotyper respectively. Twenty-five NFGNB had an agreement of 96.1% (25/26) and 61.5% (16/26) at genus and species levels with Maldi Biotyper respectively. In our study, the reporting time of antibiotic susceptibility test results of gram negative rods after direct Phoenix method ranged from 7.42 hours to 15.85 hours (mean 12.9 hours). In our study, 2.159 antimicrobial agents were tested for 120 gram negative bacteria (95 strains belonging to Enterobacteriaceae family and 25 NFGNB). Minor error rate was found to be 2.0% with the direct Phoenix method, 1.1% major error rates, and 1.2% very major error rates; making a total of 4.4% (96/2.159). Since error rates in all categories < 10%, very major error rate was < 1.5% and major error rate was < 3%, the direct Phoenix method had an acceptable agreement with the conventional Phoenix method. The direct inoculation of the Phoenix system with culture suspension obtained from positive blood culture bottles decreased reporting time of the identification and determination of the antibiotic susceptibilities for gram negative rods that cause bacteraemia. This result could be important in the clinical benefits for the patients as well as financial savings for the hospital.