Assessment of the performance of six in vitro diagnostic kits for qualitative detection of hepatitis B virus surface antigen (HBsAg) in human serum or plasma in Lomé, Togo

Background: Several in vitro diagnostic (IVD) test kits for hepatitis B surface antigen (HBsAg) are commercially available. The question is whether they are performing well for both screening and diagnosis or not? Thus, this study aimed to evaluate the performance of six commercially available HBsAg detection kits in Togo. Methods: This study was conducted at the National Reference Center for HIV/STI testing in Lomé (CNR-VIH/IST), Togo. Reference sera used for the assessment were collected from blood donors and patients with history of hepatitis B viral (HBV) infection between 2008 and 2014, and includes 200 non-reactive HBsAg and 150 reactive HBsAg sera that were confirmed with a reference method which consisted of the combination of an ELISA, a RDT, and a molecular test. Four ELISA kits (EKOlab ELISA-HBsAg; HEPALISA ULTRA; HEPALISA; Murex AgHBs Version 3) and two RDTs kits (ACON AgHBs and OnSite HBsAg Rapid Test-Cassette) were then evaluated using these serum samples. The EPI-INFO software version 7.2 was used to determine the 95% confidence interval and performed statistical analysis. Results: Reference serum samples were collected from the population with 65.0% under 40 years of age and 61.2% males. The sensitivity of the 4 ELISA tests compared to the reference method was 100%. Apart from the HEPALISA test with a specificity of 100.0%, the specificity of the other three ELISA tests (Murex HBsAg version 3, HEPALISA ULTRA and EKOlab ELISA-HBsAg) were 98.4%, 97.3% and 91.8% respectively. For the RDTs, the sensitivity of ACON HBsAg and OnSite HBsAg Rapid Test-Cassette was 70.0% and 95.6% respectively while the specificity was 100.0% for both. Conclusion: The ELISA tests evaluated were more sensitive than the RDTs, and HEPALISA test was the most efficient. Of the two RDTs, the OnSite HBsAg Rapid Test-Cassette was more sensitive. Our findings highlight the need for onsite verification of in vitro diagnostic kits for qualitative detection of hepatitis B surface antigen before their routine use in Togo. Keywords: HBV, HBsAg, Performance, IVD tes

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century