COVID-19 vaccine wastage in Africa: A case of Nigeria.

The World Health Organization has launched campaigns to boost immunisation rates to 70 percent globally by the middle of 2022. However, despite the global success of about 64% COVID-19 vaccination coverage, there is a big gap in Nigeria. To date, only 13.8% of the population has received the recommended dose. This demonstrates a significant disparity between the vaccinated and the unvaccinated. Amidst the wide gap in vaccination, COVID-19 vaccine wastage still occurs in Nigeria. At the end of 2021, it was estimated that over a million doses of the COVID-19 vaccine had been wasted. It is anticipated that there will be more COVID-19 vaccine wastage in Nigeria, because of the combined factors that threaten vaccination uptake including vaccine accessibility, lack of appropriate storage facilities, poor electricity supply, insecurity challenges, and inadequate health promotion. This results in concomitant financial and opportunity losses. In this paper, we discuss COVID-19 vaccine wastage in Nigeria including causes, and solutions that can be applied to mitigate this wastage.

Non-compartmental toxicokinetic studies of the Nigerian Naja nigricollis venom.

Snakebite envenoming (SBE) is a neglected public health problem, especially in Asia, Latin America and Africa. There is inadequate knowledge of venom toxicokinetics especially from African snakes. To mimic a likely scenario of a snakebite envenoming, we used an enzyme-linked immunosorbent assay (ELISA) approach to study the toxicokinetic parameters in rabbits, following a single intramuscular (IM) administration of Northern Nigeria Naja nigricollis venom. We used a developed and validated non-compartmental approach in the R package PK to determine the toxicokinetic parameters of the venom and subsequently used pharmacometrics modelling to predict the movement of the toxin within biological systems. We found that N. nigricollis venom contained sixteen venom protein families following a mass spectrometric analysis of the whole venom. Most of these proteins belong to the three-finger toxins family (3FTx) and venom phospholipase A2 (PLA2) with molecular weight ranging from 3 to 16 kDa. Other venom protein families were in small proportions with higher molecular weights. The N. nigricollis venom was rapidly absorbed at 0.5 h, increased after 1 h and continued to decrease until the 16th hour (Tmax), where maximum concentration (Cmax) was observed. This was followed by a decrease in concentration at the 32nd hour. The venom of N. nigricollis was found to have high volume of distribution (1250 ± 245 mL) and low clearance (29.0 ± 2.5 mL/h) with an elimination half-life of 29 h. The area under the curve (AUC) showed that the venom remaining in the plasma over 32 h was 0.0392 ± 0.0025 mg h.L-1, and the mean residence time was 43.17 ± 8.04 h. The pharmacometrics simulation suggests that the venom toxins were instantly and rapidly absorbed into the extravascular compartment and slowly moved into the central compartment. Our study demonstrates that Nigerian N. nigricollis venom contains low molecular weight toxins that are well absorbed into the blood and deep tissues. The venom could be detected in rabbit blood 48 h after intramuscular envenoming.