Ali Ahmadi

HIV-infected children are at a higher risk of Invasive Pneumococcal Disease (IPD) and its mortality, even in the era of antiretroviral therapy. Therefore, an effective vaccination strategy would be beneficial. To investigate the effectiveness of Pneumococcal Conjugate Vaccination (PCV) against IPD among HIV-Infected and HIV-Uninfected Children through a systematic review and meta-analysis. Observational studies and randomized trials on 7 years old or older children were searched in the Cochrane Library, Web of Science core collection, Embase, Medline/PubMed, and Google Scholar. Critical appraisal was done using the Cochrane risk of bias tool and the Newcastle-Ottawa quality assessment form. Effectiveness and efficacy of at least one dose of PCV was investigated among children with and without HIV considering subgroups of pneumococcal serotypes. We meta-analyzed the effect sizes using random-effects modeling. Efficacy of PCV was estimated as 45.0% (31.2, 56.1) and 52.6% (25.7, 69.8) among HIV-infected and HIV-uninfected children, respectively. Effectiveness of PCV among HIV-infected children as − 6.2% (− 67.6, 32.7) was significantly lower than HIV-uninfected children 65.1% (47.3, 76.9). Effectiveness of PCV among HIV-infected children for IPDs caused by vaccine serotypes was estimated as 7.7(− 66.7, 48.9), and for IPDs caused by non-vaccine serotypes was estimated as − 402.8(− 1856, − 29.2). Unlike the evidence on the efficacy of PCV against IPD among both of HIV-infected and HIV-uninfected children, its effectiveness against IPD among HIV-infected children is much less limited. The study protocol was registered at PROSPERO (registration ID: CRD42018108187).

The efficacy of PPV-23 vaccine on outcomes of pneumococcal disease in adults still remains controversial due mainly to the lack of consistency between the results obtained from observational studies(OSs) and those obtained from randomized controlled trials(RCTs). As a consequence, the complexity in the structure of evidence available, in turn, generates a challenge for combining disparate pieces of evidence quantitatively. In this regard, we used a hierarchical Bayesian inference-based evidence synthesis of RCTs and observational data using a two-stage approach (in addition to a traditional random-effects meta-analysis) to examine the effectiveness of PPV-23 in adults. To this end, 21 studies were included involving 826109 adult participants. By a two-stage Bayesian meta-analysis, which was directly used for combining studies of different designs, the overall log OR (95% credible interval) for IPDs was −0.1048 (−0.3920,−0.0250), indicating a significant protective effect of the vaccination against IPDs. No significant effect of PPV-23 was found on all-cause pneumonia, pneumococcal pneumonia, and death from pneumonia, which confirmed the results obtained by a traditional method followed by stratified and sensitivity analyses. The estimated overall log OR (95% credible interval) was −0.0002 (−0.0241,0.0142), −0.0002 (−0.0110,0.0122), and −6.3912 × 10⁻⁵ (−0.0219,0.0131), respectively. The PPV-23 vaccine might be effective in preventing the most severe invasive forms of pneumococcal diseases, but not effective in preventing other clinical outcomes, in the adult population of 18 years and older.

T-2 mycotoxin belongs to the Trichothecene family and has damaging effects on the immune system. To investigate the toxic effect of T-2 toxin on the percentage of peripheral blood B lymphocytes and the potential protective role of selenium and vitamin E. Frequencies of B lymphocytes (CD19+) were analyzed after injection of sublethal doses of T-2 toxin into Balb/c mice at different time points, using flowcytometry. Additionally, the effects of selenium and vitamin E on B lymphocyte, as either prophylaxis or simultaneously administered with T-2 toxin, were investigated. After injection of a sublethal dose of T-2 toxin, the number of B cells (CD19+) significantly decreased at 12 h and became normal at 72 h. When selenium was injected both 24 h before and simultaneously with T-2 toxin, it was able to inhibit B lymphocyte (CD19+) reduction. In contrast, injecting vitamin E, 24 h before or simultaneously with T-2 toxin did not regulate B lymphocyte alteration. Selenium plays pivotal role on altered B lymphocyte subset induced by T-2 toxin comparing to vitamin E.