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In a context where SARS-CoV-2 population-wide testing is implemented, clinical features and antibody response in those infected have never been documented in Africa. Yet, the information provided by analyzing data from population-wide testing is critical to understand the infection dynamics and devise control strategies. We described clinical features and assessed antibody response in people screened for SARS-CoV-2 infection. We analyzed data from a cohort of 3464 people that we molecularly screened for SARS-CoV-2 infection in our routine activity. We recorded people SARS-CoV-2 diagnosis, age, gender, blood types, white blood cells (WBC), symptoms, chronic disease status and time to SARS-CoV-2 RT-PCR conversion from positive to negative. We calculated the age-based distribution of SARS-CoV-2 infection, analyzed the proportion and the spectrum of COVID-19 severity. Furthermore, in a nested sub-study, we screened 83 COVID-19 patients and 319 contact-cases for anti-SARS-CoV-2 antibodies. Males and females accounted for respectively 51% and 49% of people screened. The studied population median and mean age were both 39 years. 592 out of 3464 people (17.2%) were diagnosed with SARS-CoV-2 infection with males and females representing, respectively, 53% and 47%. The median and mean ages of SARS-CoV-2 infected subjects were 37 and 38 years respectively. The lowest rate of infection (8%) was observed in the elderly (aged > 60). The rate of SARS-Cov-2 infection in both young (18–35 years old) and middle-aged adults (36–60 years old) was around 20%. The analysis of SARS-CoV-2 infection age distribution showed that middle-aged adults accounted for 54.7% of SARS-CoV-2 positive persons, followed respectively by young adults (33.7%), children (7.7%) and elderly (3.8%). 68% (N = 402) of SARS-CoV-2 infected persons were asymptomatic, 26.3% (N = 156) had influenza-like symptoms, 2.7% (N = 16) had influenza-like symptoms associated with anosmia and ageusia, 2% (N = 11) had dyspnea and 1% (N = 7) had respiratory failure, which resulted in death. Data also showed that 12% of SARS-CoV-2 infected subjects, had chronic diseases. Hypertension, diabetes, and asthma were the top concurrent chronic diseases representing respectively 58%, 25% and 12% of recorded chronic diseases. Half of SARS-CoV-2 RT-PCR positive patients were cured within 14 days following the initiation of the anti-COVID-19 treatment protocol. 78.3% of COVID-19 patients and 55% of SARS-CoV-2 RT-PCR confirmed negative contact-cases were positive for anti-SARS-CoV-2 antibodies. Patients with severe-to-critical illness have higher leukocytes, higher neutrophils and lower lymphocyte counts contrarily to asymptomatic patients and patients with mild-to-moderate illness. Neutrophilic leukopenia was more prevalent in asymptomatic patients and patients with mild-to-moderate disease for 4 weeks after diagnosis (27.1–42.1%). In Patients with severe-to-critical illness, neutrophilic leukocytosis or neutrophilia (35.6–50%) and lymphocytopenia (20–40%) were more frequent. More than 60% of participants were blood type O. It is also important to note that infection rate was slightly higher among A and B blood types compared with type O. In this African setting, young and middle-aged adults are most likely driving community transmission of COVID-19. The rate of critical disease is relatively low. The high rate of anti-SARS-CoV-2 antibodies observed in SARS-CoV-2 RT-PCR negative contact cases suggests that subclinical infection may have been overlooked in our setting.

Objective: Circulating levels of sex hormones vary with age. Moreover, there is emerging evidence supporting that sex hormones have an influence on the immune response of women. Here, we investigated age-associated levels of sex hormones and Mycobacterium tuberculosis (Mtb) specific cytokines response in women. Design: Using immunoassay methods, we have measured and compared secretion levels of E2, P4 and Mtb specific secretion of 11 cytokines including Granulocyte-macrophage colony-stimulating factor (GM-CSF), Interferon gamma (IFN-γ), Interleukin 1 beta (IL-1β), IL-10, IL-12 (p70), IL-2, IL-4, IL-5, IL-6, IL-8, and Tumor necrosis factor (TNF-α) in forty-two (42) HIV-negative females. Results: Estradiol (E2) and progesterone (P4) levels were significantly higher in younger women irrespective of their LTB status (p Mtb IL-8 specific response was significantly higher in women above 40 years old than in women under 40 years old. Conclusion: In premenopausal women, there is an increase in the pro-inflammatory cytokine IL-8 secretion in response to Mtb-antigen. This observation suggests an underlying link between the pro-inflammatory cytokine and age associated hormonal changes, which may have implications on the course of tuberculosis infection women.

Background: HIV-exposed uninfected (HEU)-infants have been shown to be particularly vulnerable to infections. In this population, disturbance of the gut micro-environment might increase their susce...

Background Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) has emerged throughout the world. Building knowledge around Covid‐19 is crucial to devise facts based approaches to respond efficiently against this pandemic. Aim We aimed to investigate pre‐existing humoral cross‐reactive immunity to SARS‐CoV‐2. Method We have tested the reactivity against SARS‐CoV‐2 nucleocapsid (N) antigen of sera collected from healthy healthcare volunteers in 2014. We assessed immunoglobulins reactive against SARS‐CoV‐2 N‐antigen using a well‐validated serological platform; Elecsys assay. Results Sera from 32 subjects (out of 135 [23.7%]) were reactive to SARS‐CoV‐2 N‐antigen, suggesting the presence of anti‐SARS‐CoV‐2 N‐antigen antibodies. Conclusion Although the clinical relevance of the observed reactivity can only be speculated and needs to be investigated, the implication of this finding for coronavirus disease 2019 seroepidemiological survey and vaccines' clinical trials is critical., This is the first report clearly showing a cross‐reactive humoral response against severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2). Our data is adding to the accumulating data that point toward the existence of cross‐reactive immunity to SARS‐CoV‐2, as it showed that years before the coronavirus disease 2019 pandemic people had cross‐reactive antibodies against SARS‐CoV‐2.

Tuberculosis (TB) is an intracellular infection controlled the effective recruitment of effectors immune cells at infection site. In aged premenopausal or menopausal women, there is an increased pro-inflammatory cytokines secretion suggesting an underlying link between cytokines response and estrogen (E2) and progesterone (P4) levels. In this study we compared women aged 40 years old and above (premenopausal) and women aged below 40 years old with and without latent TB infection to determine the link between E2, P4 and cytokines response to Mycobacterium tuberculosis (M. tuberculosis) stimuli. E2 and P4 levels were significantly higher in women under 40 years old than in women above 40 years old irrespective their LTB status (p < [0.0001–0.05]). In women under 40 years old, E2 and P4 were found to correlate negatively and significantly with IL-8 response to M. tuberculosis antigens stimulation ((p < [0.001–0.01]). Furthermore, M. tuberculosis IL-8 specific response was significantly higher in women above 40 years old than women under 40 years old. This study demonstrates that women aging and the linked hormonal changes are associated with hence IL-8 response to M. tuberculosis antigen, which may have implications for the age-related susceptibility or resistance to active tuberculosis.

HIV-exposed uninfected infants (HEU) represent a growing population in developing countries including Gabon. Several studies have shown the vulnerability of these infants toward infectious diseases. The aim of the study was to contribute to the global effort to understand how HIVexposure or anti retroviral therapy affects infants’ blood elements. We assessed HEU infants’ complete blood count using a blood analyzer instrument. Our investigations showed that among the observed clinically relevant hematological abnormalities events, thrombocytosis was the most prevalent clinically relevant hematological abnormality associated with HEU infants’. We showed that HEU infants had significantly higher platelets count than HUinfants. Therefore, higher level of platelets seems to characterize HEU infants when compared to HU infants.

Tuberculosis (TB) is the leading cause of death due to an infectious agent, but only a small fraction of those infected develop the disease. Cytokines are involved in the mediation and regulation of immunity, and their secretion patterns may reflect the infection status. To increase our understanding of immune response to M. tuberculosis infection, we conducted a cross-sectional study investigating M. tuberculosis infection status and comparing the release profiles of cytokines GM-CSF, IFN-γ, IL-1β, IL-10, IL-12 (p70), IL-2, IL-4, IL-5, IL-6, IL-8, TNF-α, in community controls (CCs) and healthy healthcare workers (HCWs) highly exposed to TB. Among HCWs and CCs, the probability of latent M. tuberculosis (LTB+) infection was respectively 5.4 (p = 0.002) and 3.4 (p = 0.006) times higher in men than women. The odds ratio of LTB infection was 4 times higher among HCWs in direct contact with active TB patients than other HCW (p = 0.01). Whole blood supernatant cytokine responses to M. tuberculosis antigens showed differential pro-inflammatory responses between HCWs and CCs. CCsLTB− had higher IL-1β responses than HCWsLTB− (p = 0.002). HCWsLTB+ had significantly higher IL-8 responses to M. tuberculosis antigens than HCWsLTB− (p = 0.003) and CCsLTB− (p = 0.015). HCWsLTB+/− showed weak but positive TNF-α responses to M. tuberculosis antigen stimulation compared to CCsLTB+/− (p ≤ 0.015). Looking at T-helper (1 and 2) responses, HCWsLTB+ and CCsLTB+ had significantly higher IFN-γ and IL-2 responses compared to HCWsLTB− and CCsLTB− (p LTB+ and CCsLTB+ than in non-infected CCsLTB− (p M. tuberculosis antigen specific responses in HCWsLTB+ varied based on active TB exposure gradient. HCWsLTB+ who were highly exposed to active TB (≥3 hours per day) had significantly higher IFN-γ and IL-8 responses (p ≤ 0.02) than HCWs LTB+ not in direct contact with active TB patients. HCWsLTB+ working with active TB patients for 5 to 31 years had a significantly enhanced secretion of proinflammatory cytokines (GM-CSF, IFN-γ, IL-1β, IL-2, IL-6, IL-8, IL-12p70, TNF-α) compared to HCWsLTB− (p LTB+ than HCWsLTB−. In conclusion, LTBI individuals controlling the M. tuberculosis infection have an enhanced TB specific Th1-cytokines/proinflammatory response combined with selected Th2 type/anti-inflammatory cytokines induction.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.