Performance evaluation of SARS-CoV-2 rapid diagnostic tests in Nigeria: A cross-sectional study.

The COVID-19 pandemic challenged health systems globally. Reverse transcription polymerase chain reaction (RT-PCR) is the gold standard for detecting the presence of SARS-CoV-2 in clinical samples. Rapid diagnostic test (RDT) kits for COVID-19 have been widely used in Nigeria. This has greatly improved test turnover rates and significantly decreased the high technical demands of RT-PCR. However, there is currently no nationally representative evaluation of the performance characteristics and reliability of these kits. This study assessed the sensitivity, specificity, and predictive values of ten RDT kits used for COVID-19 testing in Nigeria. This large multi-centred cross-sectional study was conducted across the 6 geo-political zones of Nigeria over four months. Ten antigen (Ag) and antibody (Ab) RDT kits were evaluated, and the results were compared with RT-PCR. One thousand, three hundred and ten (1,310) consenting adults comprising 767 (58.5%) males and 543 (41.5%) females participated in the study. The highest proportion, 757 (57.7%), were in the 20-39 years' age group. In terms of diagnostic performance, Lumira Dx (61.4, 95% CI: 52.4-69.9) had the highest sensitivity while MP SARS and Panbio (98.5, 95% CI: 96.6-99.5) had the highest specificity. For predictive values, Panbio (90.7, 95% CI: 79.7-96.9) and Lumira Dx (81.2, 95% CI: 75.9-85.7) recorded the highest PPV and NPV respectively. Ag-RDTs had better performance characteristics compared with Ab-RDTs; however, the sensitivities of all RDTs in this study were generally low. The relatively high specificity of Ag-RDTs makes them useful for the diagnosis of infection in COVID-19 suspected cases where positive RDT may not require confirmation by molecular testing. There is therefore the need to develop RDTs in-country that will take into consideration the unique environmental factors, interactions with other infectious agents, and strains of the virus circulating locally. This may enhance the precision of rapid and accurate diagnosis of COVID-19 in Nigeria.

Molecular detection of SARS-CoV-2 infection in three geo-political zones of Nigeria: a cross-sectional study.

Introduction: sequel to the emergence of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and its subsequent spread to all continents of the world, humans have continued to experience severe devastation to their health and economies. To control the spread of this virus, it is important to detect the infection in recently infected and asymptomatic individuals who are capable of infecting others. This study was designed to detect ongoing SARS-CoV-2 Infection among asymptomatic individuals in open markets across three geopolitical zones in Nigeria. Methods: nasal and oropharyngeal swab samples were collected from 2,158 study participants between December 20th, 2020 and March 20th, 2021 from large open markets across three geo-political zones (Southwest, Northwest and Southeast) of Nigeria. Virus RNA was extracted from these swab samples and real time reverse transcription polymerase chain reaction (RT-PCR) was carried out for the detection of SARS-CoV-2 specific genes. Data were analysed using descriptive statistics. Results: a total of 163 (7.6%) of the 2,158 participants enrolled for the study tested positive for SARS-CoV-2 by RT-PCR. The rate of infection was significantly higher in the North-western States of the country when compared to the western and Eastern regions (P=0.000). Similarly, the rate of infection was higher among buyers than sellers (P=0.000) and among males when compared with females, though the difference was not significant (p=0.31). Conclusion: this study shows that there is a continuous spread of SARS-CoV-2, especially among active, asymptomatic individuals across many States in the country. There is therefore need to continuously educate citizens on the need to adhere to both the non-pharmaceutical and pharmaceutical preventive measures to protect themselves and ultimately curb the spread of the virus.

Humoral and cellular immune responses to Lassa fever virus in Lassa fever survivors and their exposed contacts in Southern Nigeria.

Elucidating the adaptive immune characteristics of natural protection to Lassa fever (LF) is vital in designing and selecting optimal vaccine candidates. With rejuvenated interest in LF and a call for accelerated research on the Lassa virus (LASV) vaccine, there is a need to define the correlates of natural protective immune responses to LF. Here, we describe cellular and antibody immune responses present in survivors of LF (N = 370) and their exposed contacts (N = 170) in a LASV endemic region in Nigeria. Interestingly, our data showed comparable T cell and binding antibody responses from both survivors and their contacts, while neutralizing antibody responses were primarily seen in the LF survivors and not their contacts. Neutralizing antibody responses were found to be cross-reactive against all five lineages of LASV with a strong bias to Lineage II, the prevalent strain in southern Nigeria. We demonstrated that both T cell and antibody responses were not detectable in peripheral blood after a decade in LF survivors. Notably LF survivors maintained high levels of detectable binding antibody response for six months while their contacts did not. Lastly, as potential vaccine targets, we identified the regions of the LASV Glycoprotein (GP) and Nucleoprotein (NP) that induced the broadest peptide-specific T cell responses. Taken together this data informs immunological readouts and potential benchmarks for clinical trials evaluating LASV vaccine candidates.

Prevalence and outcome of Lassa fever among hospitalized patients in Ebonyi State, Nigeria, 2018-2019.

Lassa fever (LF) is a viral hemorrhagic illness endemic in West Africa. Annually, about 300,000-500,000 people are being infected, with about 5000 deaths. Symptoms of LF include high grade fever, headache, malaise, abdominal pain, vomiting, diarrhea, or sore throat. Terminal features may include bleeding from all orifices (mouth, nose, ear, anus and vagina), facial and neck oedema or pleural effusion. People of all ages, gender, and occupations were included in this study. A total of 440 patients' samples and Bio data were used for this study. The samples were analyzed for Lassa fever virus RNA using Real Time Reverse Transcriptase Polymerase Chain Reaction. The data obtained were analyzed using SPSS 20.0 and version 7 of Epi-Info statistical software. Analysis of these samples showed LASV prevalence of 25.7%. Chi-square analysis (p ≤ 0.05) showed that LASV infection does not depend on age, gender, or occupation. Our research re-emphasized the fact that LASV is a serious cause of fatality in humans. Our data showed that among 327 negative patients, 19 died. On the contrary, 113 LASV confirmed positive cases had 42 deaths. This result is highly significant. More so, Lassa fever disease outcome was compared across gender. There was no significant difference between the two genders. Death or recovery from LF infection does not depend on sex. However, recovery from LF significantly depends on age of the patient. Fatal outcome is significantly higher among adults/elderly. We aim to raise awareness to the recurrence of LASV in Ebonyi State and urgent need for other medical interventions, including other therapeutic measures, and possible vaccine production, considering the impact of this virus.