Immunological insights into COVID-19 in Southern Nigeria.

Introduction: One of the unexpected outcomes of the COVID-19 pandemic was the relatively low levels of morbidity and mortality in Africa compared to the rest of the world. Nigeria, Africa's most populous nation, accounted for less than 0.01% of the global COVID-19 fatalities. The factors responsible for Nigeria's relatively low loss of life due to COVID-19 are unknown. Also, the correlates of protective immunity to SARS-CoV-2 and the impact of pre-existing immunity on the outcome of the COVID-19 pandemic in Africa are yet to be elucidated. Here, we evaluated the natural and vaccine-induced immune responses from vaccinated, non-vaccinated and convalescent individuals in Southern Nigeria throughout the three waves of the COVID-19 pandemic in Nigeria. We also examined the pre-existing immune responses to SARS-CoV-2 from samples collected prior to the COVID-19 pandemic. Methods: We used spike RBD and N- IgG antibody ELISA to measure binding antibody responses, SARS-CoV-2 pseudotype assay protocol expressing the spike protein of different variants (D614G, Delta, Beta, Omicron BA1) to measure neutralizing antibody responses and nucleoprotein (N) and spike (S1, S2) direct ex vivo interferon gamma (IFNγ) T cell ELISpot to measure T cell responses. Result: Our study demonstrated a similar magnitude of both binding (N-IgG (74% and 62%), S-RBD IgG (70% and 53%) and neutralizing (D614G (49% and 29%), Delta (56% and 47%), Beta (48% and 24%), Omicron BA1 (41% and 21%)) antibody responses from symptomatic and asymptomatic survivors in Nigeria. A similar magnitude was also seen among vaccinated participants. Interestingly, we revealed the presence of preexisting binding antibodies (N-IgG (60%) and S-RBD IgG (44%)) but no neutralizing antibodies from samples collected prior to the pandemic. Discussion: These findings revealed that both vaccinated, non-vaccinated and convalescent individuals in Southern Nigeria make similar magnitude of both binding and cross-reactive neutralizing antibody responses. It supported the presence of preexisting binding antibody responses among some Nigerians prior to the COVID-19 pandemic. Lastly, hybrid immunity and heterologous vaccine boosting induced the strongest binding and broadly neutralizing antibody responses compared to vaccine or infection-acquired immunity alone.

Lassa virus in novel hosts: insights into the epidemiology of lassa virus infections in southern Nigeria.

Identification of the diverse animal hosts responsible for spill-over events from animals to humans is crucial for comprehending the transmission patterns of emerging infectious diseases, which pose significant public health risks. To better characterize potential animal hosts of Lassa virus (LASV), we assessed domestic and non-domestic animals from 2021-2022 in four locations in southern Nigeria with reported cases of Lassa fever (LF). Birds, lizards, and domestic mammals (dogs, pigs, cattle and goats) were screened using RT-qPCR, and whole genome sequencing was performed for lineage identification on selected LASV positive samples. Animals were also screened for exposure to LASV by enzyme-linked immunosorbent assay (ELISA). Among these animals, lizards had the highest positivity rate by PCR. Genomic sequencing of samples in most infected animals showed sub-lineage 2 g of LASV. Seropositivity was highest among cattle and lowest in pigs. Though the specific impact these additional hosts may have in the broader virus-host context are still unknown - specifically relating to pathogen diversity, evolution, and transmission - the detection of LASV in non-rodent hosts living in proximity to confirmed human LF cases suggests their involvement during transmission as potential reservoirs. Additional epidemiological data comparing viral genomes from humans and animals, as well as those circulating within the environment will be critical in understanding LASV transmission dynamics and will ultimately guide the development of countermeasures for this zoonotic health threat.

Emergence and spread of two SARS-CoV-2 variants of interest in Nigeria.

Identifying the dissemination patterns and impacts of a virus of economic or health importance during a pandemic is crucial, as it informs the public on policies for containment in order to reduce the spread of the virus. In this study, we integrated genomic and travel data to investigate the emergence and spread of the SARS-CoV-2 B.1.1.318 and B.1.525 (Eta) variants of interest in Nigeria and the wider Africa region. By integrating travel data and phylogeographic reconstructions, we find that these two variants that arose during the second wave in Nigeria emerged from within Africa, with the B.1.525 from Nigeria, and then spread to other parts of the world. Data from this study show how regional connectivity of Nigeria drove the spread of these variants of interest to surrounding countries and those connected by air-traffic. Our findings demonstrate the power of genomic analysis when combined with mobility and epidemiological data to identify the drivers of transmission, as bidirectional transmission within and between African nations are grossly underestimated as seen in our import risk index estimates.

Implementation of Isoniazid Preventive Therapy among People Living with HIV in Northwestern Nigeria: Completion Rate and Predictive Factors.

BACKGROUND: Despite proven benefits of isoniazid preventive therapy (IPT) for people living with HIV (PLHIV), its implementation remains limited in low-resource settings. There are also programmatic concerns of the completion rate of IPT particularly when full integration with other HIV services has not been achieved. AIM: The aim of this study was to determine the completion rate of IPT and predictive factors among PLHIV attending six government hospitals in Kebbi state, Northern Nigeria. METHODS: This was a retrospective cohort study of program data spanning a 5-year period (December 2010-June 2016). Data were collected between January 2017 and June 2017. RESULTS: A total of 1,134 IPT patients were enrolled of whom 740 (65.3%) were female. The mean age was 40.3 ± 3.7 years. Four hundred and fifty-four (40%) of those who initiated IPT completed the 6-month course. Of the 680 (60%) IPT noncompleters, 117 (17.2%) were lost to follow-up by month 1, 305 (44.9%) by month 2, 156 (22.9%) by month 3, 48 (7.1%) by month 4, and 54 (7.9%) by month 5. Being initiated on IPT by a pharmacist (adjusted odds ratio [aOR]: 23.7, 95% confidence interval [CI]: 16.5-33.9) and receiving ≤2 tuberculosis screening evaluation during IPT period (aOR: 0.58, 95% CI: 0.43-0.78) were associated with a higher and lower risk of completing IPT, respectively, whereas age, sex, and anti-retroviral therapy (ART) status were not significantly associated. CONCLUSION: IPT completion rate among PLHIV is relatively low, highlighting the need to strengthen IPT rollout in public health facilities in Nigeria. Pharmacy-led IPT adherence education and regular clinical evaluation may improve IPT completion rates, along with synchronizing and prepackaging IPT and ART resupplies for PLHIV.