Search

Background: Heterologous COVID-19 booster vaccination is an alternative strategy to homologous vaccination, especially in developing countries, due to shortages, delays, or unequal distribution of COVID-19 vaccines. We compared cohorts vaccinated with different vaccine combinations to investigate whether a heterologous booster dose of mRNA-based BNT162b2 vaccine boosts the immune response in individuals primed with the CoronaVac vaccine. Methods: Anti-RBD IgG is generally measured 4 weeks after primary immunization and 4 weeks after booster vaccination. Data on anti-receptor-binding domain (anti-RBD) IgG antibody titers and clinical characteristics were provided by infection control units. Results: The highest median anti-RBD IgG antibody titers (14589 AU/mL) after primary immunization was observed in the group vaccinated with two doses of BNT162b2 vaccine. Antibody titers were lower 4 months or more after the second CoronaVac vaccine dose in CoronaVac recipients with or without previous COVID-19. In the homologous COVID-19 booster vaccine group (primed with two doses of CoronaVac 4 weeks apart and a single booster dose of CoronaVac) the median anti-RBD titers decreased from 1025 to 242 AU/mL before the booster dose. In the heterologous group (primed with two doses of CoronaVac 4 weeks apart and a single booster dose of BNT162b2), the median anti-RBD titer increased to 31624 AU/mL, a 132-fold increase, 16 days after the booster dose. Conclusions: After the second dose of CoronaVac, protective neutralizing antibody levels decrease over time, and a booster dose is required. Heterologous COVID-19 booster vaccination with BNT162b2 is effective at boosting neutralizing antibody levels.

SUMMARYA better understanding of the innate and adaptive cells in the COVID-19 disease caused by the SARS-CoV-2 coronavirus is a necessity for the development of effective treatment methods and vaccines. We studied phenotypic features of innate and adaptive immune cells, oxidative burst, phagocytosis and apoptosis. One hundred and three patients with COVID-19 grouped according to their clinical features as mild (35%), moderate (40.8%), and severe (24.3%) were included in the study. Monocytes from all COVID-19 patients were CD16+ pro-inflammatory monocytes. Neutrophils were mature and functional. No defect has been found in ROS production of monocytes and neutrophils as well as no defect in their apoptosis. As bridging cells of the innate and adaptive immune system; the percentage of NK cells was in normal range whereas the percentages of CD3-CD8+CD56+ innate lymphoid and CD3+CD56+ NK like T cells were found to be high in the severe cases of COVID-19. Although absolute numbers of all lymphocyte subsets were low and showed a tendency for a gradual decrease in accord with the disease progression, in all COVID-19 patients, the lymphocyte subset with the most decreased absolute number was B lymphocytes, followed by CD4 + T cells in the severe cases. The percentages of suppressive, CD3+CD4-CD8-; HLA-DR+CD3+ and CD28-CD8+ cells were found to be significantly increased. Importantly, we demonstrated spontaneous caspase-3 activation and increased lymphocyte apoptosis. Altogether our data suggest that SARS-CoV-2 primarily affects lymphocytes not innate cells. So that, it may interrupt the cross-talk between adaptive and innate immune systems.

Background: The fatality attributed to pandemic influenza A H1N1 was not clear in the literature. We described the predictors for fatality related to pandemic influenza A H1N1 infection among hospitalized adult patients. Methods: This is a multicenter study performed during the pandemic influenza A H1N1 [A(H1N1) pdm09] outbreak which occurred in 2009 and 2010. Analysis was performed among laboratory confirmed patients. Multivariate analysis was performed for the predictors of fatality. Results: In the second wave of the pandemic, 848 adult patients were hospitalized because of suspected influenza, 45 out of 848 (5.3%) died, with 75% of fatalities occurring within the first 2 weeks of hospitalization. Among the 241 laboratory confirmed A(H1N1) pdm09 patients, the case fatality rate was 9%. In a multivariate logistic regression model that was performed for the fatalities within 14 days after admission, early use of neuraminidase inhibitors was found to be protective (Odds ratio: 0.17, confidence interval: 0.03-0.77, p = 0.022), nosocomial infections (OR: 5.7, CI: 1.84-18, p = 0.013), presence of malignant disease (OR: 3.8, CI: 0.66-22.01, p = 0.133) significantly increased the likelihood of fatality. Conclusions: Early detection of the infection, allowing opportunity for the early use of neuraminidase inhibitors, was found to be important for prevention of fatality. Nosocomial bacterial infections and underlying malignant diseases increased the rate of fatality.