Evaluation of cross-neutralizing immunity following COVID-19 primary series vaccination during the Omicron surge in Tanzania.

COVID-19 vaccine became available in Tanzania during the first wave of the Omicron variant. During that time community seroprevalence of SARS-CoV-2 was already at 50%-80%. To date, it remains largely unknown whether ongoing vaccination with the primary series vaccines has any meaningful immune-boosting effects against newer Omicron subvariants. Therefore, we tested cross-neutralizing capacity of antibodies elicited by infection, vaccination, or both against SARS-CoV-2 Omicron subvariants BA.1, and the newer subvariants BQ.1.1 and XBB.1.5. that were unexperienced by this population. Participants who were either SARS-CoV-2 infected-only (n = 28), infected vaccinated (n = 22), or vaccinated-only (n = 73) were recruited from Dar-es-Salaam, Tanzania, between April and December 2022. Plasma 50% neutralization titers (NT50) against SARS-CoV-2 wild-type strain and Omicron subvariants were quantified by a lentiviral-based pseudo-virus assay. Percentage of participants with neutralizing activity against WT and BA.1 was high (>85%) but was reduced against BQ.1.1 (64%-77%) and XBB.1.5 (35%-68%) subvariants. The low median cross-neutralization titer was slightly higher in the infected vaccinated group compared to vaccine-only group against BQ.1.1 (NT50 148 vs. 85, p = 0.032) and XBB.1.5 (NT50 85 vs. 37 p = 0.022) subvariants. In contrast, vaccine-boost among the infected vaccinated did not result to increased cross-neutralization compared to infected-only participants (BQ.1.1 [NT50 of 148 vs. 100, p = 0.501] and XBB.1.5 [NT50 86 vs. 45, p = 0.474]). We report severely attenuated neutralization titers against BQ.1.1 and XBB.1.5 subvariants among vaccinated participants, which marginally improved in the infected vaccinated participants. Our findings call for further studies to evaluate effectiveness of the primary series vaccines in preventing severe infection and mortality against the newer variants.

A ten year review of the sickle cell program in Muhimbili National Hospital, Tanzania.

BACKGROUND: Africa has the highest burden of Sickle cell disease (SCD) but there are few large, systematic studies providing reliable descriptions of the disease spectrum. Tanzania, with 11,000 SCD births annually, established the Muhimbili Sickle Cell program aiming to improve understanding of SCD in Africa. We report the profile of SCD seen in the first 10 years at Muhimbili National Hospital (MNH). METHODS: Individuals seen at MNH known or suspected to have SCD were enrolled at clinic and laboratory testing for SCD, haematological and biochemical analyses done. Ethnicity was self-reported. Clinical and laboratory features of SCD were documented. Comparison was made with non-SCD population as well as within 3 different age groups (< 5, 5-17 and ≥ 18 years) within the SCD population. RESULTS: From 2004 to 2013, 6397 individuals, 3751 (58.6%) SCD patients, were enrolled, the majority (47.4%) in age group 5-17 years. There was variation in the geographical distribution of SCD. Individuals with SCD compared to non-SCD, had significantly lower blood pressure and peripheral oxygen saturation (SpO2). SCD patients had higher prevalence of severe anemia, jaundice and desaturation (SpO2 < 95%) as well as higher levels of reticulocytes, white blood cells, platelets and fetal hemoglobin. The main causes of hospitalization for SCD within a 12-month period preceding enrolment were pain (adults), and fever and severe anemia (children). When clinical and laboratory features were compared in SCD within 3 age groups, there was a progressive decrease in the prevalence of splenic enlargement and an increase in prevalence of jaundice. Furthermore, there were significant differences with monotonic trends across age groups in SpO2, hematological and biochemical parameters. CONCLUSION: This report confirms that the wide spectrum of clinical expression of SCD observed elsewhere is also present in Tanzania, with non-uniform geographical distribution across the country. Age-specific analysis is consistent with different disease-patterns across the lifespan.

Limited Exchange Transfusion Can Be Very Beneficial in Sickle Cell Anemia with Acute Chest Syndrome: A Case Report from Tanzania.

Acute chest syndrome (ACS) is a life-threatening complication of sickle cell disease (SCD) with blood transfusion an integral part in its management. Red cell exchange (RCE) transfusion is usually regarded as preferable to top-up transfusion, because it reduces the proportion of Hemoglobin (Hb) S while at the same time avoiding circulatory overload. Despite its obvious benefits, RCE is underutilized, particularly in low-resource settings which may be due to scarcity of blood products and of expertise in carrying out exchange transfusion. We report on a young woman with SCD with severe ACS who responded promptly and dramatically to a RCE of only 0.95 L (instead of the recommended 1.4 L) and had in the end an HbS level of 48% (instead of the recommended level below 30%). Limited RCE resulted in significant clinical improvement. We suggest that limited RCE may be of benefit than no RCE in SCD patients with ACS, particularly in settings where RCE is not available.

Osteosarcoma of the lower limb metastasized to the septum and right side of the heart: a case report.

BACKGROUND: Metastatic cardiac tumors are far more common than primary tumors. Although the hematogenous spread of osteosarcoma is well known, the imaging findings of cardiovascular involvement by osteosarcoma are seldom reported and can be difficult to recognize. CASE PRESENTATION: A 21-year-old man of African descent presented to our center complaining of shortness of breath, awareness of heart beats, easy fatigability, swelling of lower limbs, and left-side chest discomfort for the past 6 months getting worse for the last 3 months prior to his third readmission. In 2004 he was admitted with the diagnosis of osteosarcoma of his left calcaneus bone confirmed by bone biopsy and treated at an oncology center with several cycles of radiotherapy and chemotherapy; he was declared cured after 5 years of annual clinical and radiological skeletal survey follow-ups. In the current admission, a physical examination revealed bilateral lower limb swelling, pansystolic murmur on the left side of his sternum at fourth intercostal space (tricuspid area) grade three, hepatomegaly with a liver span of 17 cm, and a positive fluid test and shifting dullness. CONCLUSIONS: This case report presents a 21-year-old man with relapsed osteosarcoma manifesting as metastatic lesions to his right ventricle encroaching on his interventricular septum, which was identified by transthoracic/transesophageal echocardiography computed tomography scan and cardiac magnetic resonance imaging.