2.5. Safety Assessment

The safety of the tested product was evaluated through taking medical history, physical examination, vital signs, 12-lead ECG, clinical laboratory tests and incidence of AEs. Physical examinations were performed by study clinicians and included the examination of the following: general appearance, eyes, ears, nose, throat, chest/respiratory, heart/cardiovascular, gastrointestinal/liver, musculoskeletal/extremities, dermatological/skin, thyroid/neck, lymph nodes, and neurological/psychiatric systems.

The vital signs observed during the study included systolic blood pressure, diastolic blood pressure, pulse rate, and body temperature at baseline and 0, 1, 2, 3, 4, 5, 6, 7, 14, 28 and 56 days. A 12-lead ECG was performed at baseline and at 3, 7, 14, 28 and 56 days.

Safety laboratory tests (including hematology and chemistry) were performed at baseline and at 3, 7, 14 and 28 days. A total of 1 mL of venous blood sample was collected into a K3 EDTA vacutainer tube (Greiner Bio-one) and a Z-serum clot activator tube (Greiner Bio-one) for hematology and biochemistry analysis, respectively. For hematological analysis, a fully automated 5-part differential hematology analyzer (Sysmex XS-800i, Sysmex Corporation, Japan) was used to analyze samples within 8 h of blood draw. The results printed out were double-checked by two independent, qualified technicians before being handed out to clinicians for clinical management. For biochemical analysis, samples were allowed to stand at room temperature for 30 min before separating the serum by centrifugation at 3000 rpm for 10 min. The serum was analyzed using Cobas Integra 400 Plus (Roche Diagnostic, Switzerland) within 24 h after the blood draw. If the testing was to be delayed, serum for biochemical analyses was stored at −20 °C and subjected to a single freeze–thaw cycle at the time of analysis, and whole EDTA blood for hematological analyses was stored at 4–8 °C and analyzed within 24 h after the blood draw.

For the quality assurance of the analyzers, internal quality control (IQC) and external quality assurance (EQA) quality assessments were performed on the main and back-up analyzers according to standard operating procedures. IQC was carried out daily using quality control materials supplied by the respective analyzer’s manufacturer. EQA was performed monthly using materials supplied by an independent EQA firm (the College of American Pathologists (CAP) for the biochemistry analyzer and the United Kingdom National External Quality Assessment Scheme (UK NEQAS) for the hematology analyzer). Only the analyzers that passed the IQC and EQA assessments were used for clinical sample analysis.

White blood cell count (3.48 to 9.11 × 10³/L), red blood cell count (4.39 to 6.5 × 106/L), hemoglobin (12.6 to 17.3 g/dL), platelets (107 to 396.2 × 10³/L), neutrophil counts (1.18 to 5.46 × 10³/L), lymphocyte counts (1.19 to 3.4 × 10³/L), and eosinophil counts (0 to 0.78 × 10³/L) were all examined. The analysis of liver function tests included AST (12.3 to 74.7 U/L), ALT (3.5 to 46.8 U/L) and total bilirubin (3.1–31.1μmol/L). The serum creatinine level (49 to 95.3 μmol/L) was measured as a function of the kidney.

These laboratory reference intervals were derived from a local or regional population that was more likely to have similar biological characteristics, as stipulated in the Clinical and Laboratory Standards Institute (CLSI) guidelines [24]. The correct interpretation of laboratory results requires accurate clinical laboratory reference intervals derived from a local or regional population [25].

Solicited adverse events were monitored and recorded up to day 7, while unsolicited adverse events were monitored and recorded up to day 28 after the first administration of the tested product.

All study volunteers were monitored throughout the study for serious adverse events (SAEs). The study clinicians were responsible for evaluating all AEs in terms of intensity (mild, moderate, or severe), duration, severity, outcome, and relationship to the study drug. The Standard Treatment Guidelines & National Essential Medicines List, Tanzania Mainland (STG/NEMLIT-2017); Division of AIDS (DAIDS) Table for Grading the Severity of Adult and Pediatric Adverse Events (Corrected Version 2.1, July 2017); US FDA, Toxicity Grading Scale for Healthy Adult and Adolescent Volunteers Enrolled in Preventive Vaccine Clinical Trials: Guidance for Industry (September 2007); and Common Terminology Criteria for Adverse Events (CTCAE) (Version 5.0, November 2017) were used to develop the grading criteria for adverse events.