The COVID-19 pandemic has currently overtaken every other health issue throughout the world. There are numerous ways in which this will impact existing public health issues. Here we reflect on the interactions between COVID-19 and tuberculosis (TB), which still ranks as the leading cause of death from a single infectious disease globally. There may be grave consequences for existing and undiagnosed TB patients globally, particularly in low and middle income countries (LMICs) where TB is endemic and health services poorly equipped. TB control programmes will be strained due to diversion of resources, and an inevitable loss of health system focus, such that some activities cannot or will not be prioritised. This is likely to lead to a reduction in quality of TB care and worse outcomes. Further, TB patients often have underlying co-morbidities and lung damage that may make them prone to more severe COVID-19. The symptoms of TB and COVID-19 can be similar, with for example cough and fever. Not only can this create diagnostic confusion, but it could worsen the stigmatization of TB patients especially in LMICs, given the fear of COVID-19. Children with TB are a vulnerable group especially likely to suffer as part of the "collateral damage". There will be a confounding of symptoms and epidemiological data through co-infection, as happens already with TB-HIV, and this will require unpicking. Lessons for COVID-19 could be learned from the vast experience of running global TB control programmes, while the astonishingly rapid and relatively well coordinated response to COVID-19 demonstrates how existing programmes could be significantly improved.

BackgroundFew studies have evaluated the association between preexisting vitamin D deficiency and incident tuberculosis (TB). We assessed the impact of baseline vitamins D levels on TB disease risk.Methods and findingsWe assessed the association between baseline vitamin D and incident TB in a prospective cohort of 6,751 HIV-negative household contacts of TB patients enrolled between September 1, 2009, and August 29, 2012, in Lima, Peru. We screened for TB disease at 2, 6, and 12 months after enrollment. We defined cases as household contacts who developed TB disease at least 15 days after enrollment of the index patient. For each case, we randomly selected four controls from among contacts who did not develop TB disease, matching on gender and year of age. We also conducted a one-stage individual-participant data (IPD) meta-analysis searching PubMed and Embase to identify prospective studies of vitamin D and TB disease until June 8, 2019. We included studies that assessed vitamin D before TB diagnosis. In the primary analysis, we defined vitamin D deficiency as 25–(OH)D < 50 nmol/L, insufficiency as 50–75 nmol/L, and sufficiency as >75nmol/L. We estimated the association between baseline vitamin D status and incident TB using conditional logistic regression in the Lima cohort and generalized linear mixed models in the meta-analysis. We further defined severe vitamin D deficiency as 25–(OH)D < 25 nmol/L and performed stratified analyses by HIV status in the IPD meta-analysis. In the Lima cohort, we analyzed 180 cases and 709 matched controls. The adjusted odds ratio (aOR) for TB risk among participants with baseline vitamin D deficiency compared to sufficient vitamin D was 1.63 (95% CI 0.75–3.52; p = 0.22). We included seven published studies in the meta-analysis and analyzed 3,544 participants. In the pooled analysis, the aOR was 1.48 (95% CI 1.04–2.10; p = 0.03). The aOR for severe vitamin D deficiency was 2.05 (95% CI 0.87–4.87; p trend for decreasing 25–(OH)D levels from sufficient vitamin D to severe deficiency = 0.02). Among 1,576 HIV-positive patients, vitamin D deficiency conferred a 2-fold (aOR 2.18, 95% CI 1.22–3.90; p = 0.01) increased risk of TB, and the aOR for severe vitamin D deficiency compared to sufficient vitamin D was 4.28 (95% CI 0.85–21.45; p = 0.08). Our Lima cohort study is limited by the short duration of follow-up, and the IPD meta-analysis is limited by the number of possible confounding covariates available across all studies.ConclusionOur findings suggest vitamin D predicts TB disease risk in a dose-dependent manner and that the risk of TB disease is highest among HIV-positive individuals with severe vitamin D deficiency. Randomized control trials are needed to evaluate the possible role of vitamin D supplementation on reducing TB disease risk.

Unlike HIV-1-infected people, most HIV-2-infected subjects maintain a healthy CD4+ T cell count and a strong HIV-specific CD4+ T cell response. To define the cellular immunological correlates of good prognosis in HIV-2 infection, we conducted a cross-sectional study of HIV Gag-specific T cell function in HIV-1- and HIV-2-infected Gambians. Using cytokine flow cytometry and lymphoproliferation assays, we show that HIV-specific CD4+ T cells from HIV-2-infected individuals maintained proliferative capacity, were not terminally differentiated (CD57−), and more frequently produced IFN-γ or IL-2 than CD4+ T cells from HIV-1-infected donors. Polyfunctional (IFN-γ+/IL-2+) HIV-specific CD4+ T cells were found exclusively in HIV-2+ donors. The disparity in CD4+ T cell responses between asymptomatic HIV-1- and HIV-2-infected subjects was not associated with differences in the proliferative capacity of HIV-specific CD8+ T cells. This study demonstrates that HIV-2-infected donors have a well-preserved and functionally heterogeneous HIV-specific memory CD4+ T cell response that is associated with delayed disease progression in the majority of infected people.

Greater Banjul area of The Gambia. To evaluate uptake, adherence and completion of treatment among tuberculosis (TB) exposed children in The Gambia when isoniazid preventive treatment (IPT) is delivered at home Child (age <5 years) contacts of adults with smear-positive TB were prospectively enrolled. Following symptom screening, tuberculin skin testing and clinical evaluation where indicated, those without disease were placed on daily isoniazid, provided monthly at home. Adherence was assessed by pill counts and IsoScreen urine test. Of 404 contacts aged<5 years, 368 (91.1%) were offered IPT. Of the 328 (89.4%) for whom consent was received and who commenced IPT, 18 (5.5%) dropped out and 310 (94.5%) remained on IPT to the end of the 6-month regimen. Altogether, 255/328 children (77.7%, 95%CI 73.2-82.2) completed all 6 months, with good adherence. The IsoScreen test was positive in 85.3% (435/510) of all tests among those defined as having good adherence by pill count and in 16% (8/50) of those defined as having poor adherence ( < 0.001). A cascade of care analysis showed an overall completion rate with good adherence of 61% for all child contacts. Home-delivered IPT among child contacts of adults with smear-positive TB in The Gambia achieved verifiable high uptake and adherence rates. System rather than patient factors are likely to determine the success of IPT at national level.