Serial QuantiFERON testing and tuberculosis disease risk among young children: an observational cohort study.

BACKGROUND: The value of quantitative interferon-γ release assay results for predicting progression from Mycobacterium tuberculosis infection to active disease is unknown. We aimed to investigate the relation between QuantiFERON-TB Gold In-Tube (QFT) conversion interferon-γ values and risk of subsequent active tuberculosis disease and of QFT reversion. METHODS: We analysed data from a reported vaccine efficacy trial of the tuberculosis vaccine MVA85A in South Africa. QFT negative, HIV uninfected young children aged 18-24 weeks were enrolled. We stratified participants by quantitative QFT result (interferon-γ <0·35 IU/mL, 0·35-4·00 IU/mL, and >4·00 IU/mL) at the intermediate study visit (day 336) and determined risk of progression to active tuberculosis disease over the subsequent 6-24 months. No QFT differences were observed between placebo and MVA85A groups at day 336 or end of study; therefore, both groups were included in analyses. Study clinicians were not masked to QFT values, but strict case definitions were used that excluded QFT results. We used generalised additive models to evaluate the quantitative relation between day 336 QFT value and subsequent disease risk, and we compared disease rates between QFT strata using a two-sample Poisson test. FINDINGS: Among 2512 young children with QFT tests done at day 336, 172 (7%) were positive; 87 (7%) of 1267 in placebo group and 85 (7%) of 1245 in the MVA85A group (p=1·00). Compared with QFT non-converters (tuberculosis disease incidence 0·7 per 100 person-years [95% CI 0·4-1·1]), children with QFT conversion at interferon-γ values between 0·35-4·00 IU/mL did not have significantly increased risk of disease (2·5 per 100 person-years [95% CI 0·4-9·4]; incidence rate ratio (IRR) 3·7 (95% CI 0·4-15·8; p=0·23). However, QFT conversion at interferon-γ values higher than 4·00 IU/mL was associated with substantially increased disease incidence (28·0 per 100 person-years [95% CI 14·9-45·7]) compared with non-converters (IRR 42·5 [95% CI 17·2-99·7]; p<0·0001), and compared with children with interferon-γ values between 0·35-4·00 IU/mL (IRR 11·4 [95% CI 2·4-107·2]; p=0·00047). Among 91 QFT converters who were given a repeat test, 53 (58%) reverted from positive to negative. QFT reversion risk was inversely associated with interferon-γ value at QFT conversion and was highest with interferon-γ values less than 4·00 IU/mL (47 [77%] of 61). INTERPRETATION: In young children, tuberculosis disease risk was not significantly increased, and QFT reversion was common, following QFT conversion at interferon-γ values up to 10 times the recommended test threshold (0·35 IU/mL). By contrast, QFT conversion at very high interferon-γ values (>4·00 IU/mL) warrants intensified diagnostic and preventive intervention because of the extremely high risk of tuberculosis disease in these young children. FUNDING: Aeras, Wellcome Trust, and Oxford-Emergent Tuberculosis Consortium (OETC) were the funders of the MVA85A 020 Trial. National Institute of Allergy and Infectious Diseases supported this analysis.

The Role of Clinical Symptoms in the Diagnosis of Intrathoracic Tuberculosis in Young Children.

BACKGROUND: Childhood tuberculosis (TB) is usually Mycobacterium tuberculosis (MTB) culture negative. Furthermore, clinical presentation may be altered by active case finding, isoniazid prophylaxis and early treatment. We aimed to establish the value of presenting symptoms for intrathoracic TB case diagnosis among young children. METHODS: Healthy, HIV-uninfected, South African infants in an efficacy trial of a novel TB vaccine (MVA85A) were followed for 2 years for suspected TB. When suspected, investigation followed a standardized algorithm comprising symptom history, QuantiFERON Gold-in-Tube, chest radiography (CXR), MTB culture and Xpert MTB/RIF from paired gastric lavage and induced sputa. Adjusted odds ratios and 95% confidence intervals describe the associations between symptoms and positive MTB culture or Xpert MTB/RIF, and CXR compatible with intrathoracic TB. RESULTS: Persistent cough was present in 172/1017 (16.9%) of the children investigated for TB. MTB culture/Xpert MTB/RIF was positive in 38/1017 children (3.7%); and CXR was positive, that is, compatible with intrathoracic TB, in 131/1017 children (12.9%). Children with persistent cough had more than triple the odds of a positive MTB culture/Xpert MTB/RIF (adjusted odds ratios: 3.3, 95% confidence interval: 1.5-7.0) and positive CXR (adjusted odds ratios: 3.5, 95% confidence interval: 2.2-5.5). Persistent cough was the only symptom that differentiated children with severe (56.5%) from nonsevere intrathoracic TB disease (28.2%; P = 0.001). CONCLUSION: Persistent cough was the cardinal diagnostic symptom associated with microbiologic and radiologic evidence, and disease severity, of intrathoracic TB. Symptom-based definitions of TB disease for diagnostic, preventive and therapeutic studies should prioritize persistent cough above other symptoms compatible with childhood TB.

Safety, immunogenicity, and efficacy of the candidate tuberculosis vaccine MVA85A in healthy adults infected with HIV-1: a randomised, placebo-controlled, phase 2 trial.

BACKGROUND: HIV-1 infection is associated with increased risk of tuberculosis and a safe and effective vaccine would assist control measures. We assessed the safety, immunogenicity, and efficacy of a candidate tuberculosis vaccine, modified vaccinia virus Ankara expressing antigen 85A (MVA85A), in adults infected with HIV-1. METHODS: We did a randomised, double-blind, placebo-controlled, phase 2 trial of MVA85A in adults infected with HIV-1, at two clinical sites, in Cape Town, South Africa and Dakar, Senegal. Eligible participants were aged 18-50 years, had no evidence of active tuberculosis, and had baseline CD4 counts greater than 350 cells per µL if they had never received antiretroviral therapy or greater than 300 cells per µL (and with undetectable viral load before randomisation) if they were receiving antiretroviral therapy; participants with latent tuberculosis infection were eligible if they had completed at least 5 months of isoniazid preventive therapy, unless they had completed treatment for tuberculosis disease within 3 years before randomisation. Participants were randomly assigned (1:1) in blocks of four by randomly generated sequence to receive two intradermal injections of either MVA85A or placebo. Randomisation was stratified by antiretroviral therapy status and study site. Participants, nurses, investigators, and laboratory staff were masked to group allocation. The second (booster) injection of MVA85A or placebo was given 6-12 months after the first vaccination. The primary study outcome was safety in all vaccinated participants (the safety analysis population). Safety was assessed throughout the trial as defined in the protocol. Secondary outcomes were immunogenicity and vaccine efficacy against Mycobacterium tuberculosis infection and disease, assessed in the per-protocol population. Immunogenicity was assessed in a subset of participants at day 7 and day 28 after the first and second vaccination, and M tuberculosis infection and disease were assessed at the end of the study. The trial is registered with ClinicalTrials.gov, number NCT01151189. FINDINGS: Between Aug 4, 2011, and April 24, 2013, 650 participants were enrolled and randomly assigned; 649 were included in the safety analysis (324 in the MVA85A group and 325 in the placebo group) and 645 in the per-protocol analysis (320 and 325). 513 (71%) participants had CD4 counts greater than 300 cells per µL and were receiving antiretroviral therapy; 136 (21%) had CD4 counts above 350 cells per µL and had never received antiretroviral therapy. 277 (43%) had received isoniazid prophylaxis before enrolment. Solicited adverse events were more frequent in participants who received MVA85A (288 [89%]) than in those given placebo (235 [72%]). 34 serious adverse events were reported, 17 (5%) in each group. MVA85A induced a significant increase in antigen 85A-specific T-cell response, which peaked 7 days after both vaccinations and was primarily monofunctional. The number of participants with negative QuantiFERON-TB Gold In-Tube findings at baseline who converted to positive by the end of the study was 38 (20%) of 186 in the MVA85A group and 40 (23%) of 173 in the placebo group, for a vaccine efficacy of 11·7% (95% CI -41·3 to 44·9). In the per-protocol population, six (2%) cases of tuberculosis disease occurred in the MVA85A group and nine (3%) occurred in the placebo group, for a vaccine efficacy of 32·8% (95% CI -111·5 to 80·3). INTERPRETATION: MVA85A was well tolerated and immunogenic in adults infected with HIV-1. However, we detected no efficacy against M tuberculosis infection or disease, although the study was underpowered to detect an effect against disease. Potential reasons for the absence of detectable efficacy in this trial include insufficient induction of a vaccine-induced immune response or the wrong type of vaccine-induced immune response, or both. FUNDING: European & Developing Countries Clinical Trials Partnership (IP.2007.32080.002), Aeras, Bill & Melinda Gates Foundation, Wellcome Trust, and Oxford-Emergent Tuberculosis Consortium.

Safety and efficacy of MVA85A, a new tuberculosis vaccine, in infants previously vaccinated with BCG: a randomised, placebo-controlled phase 2b trial.

BACKGROUND: BCG vaccination provides incomplete protection against tuberculosis in infants. A new vaccine, modified Vaccinia Ankara virus expressing antigen 85A (MVA85A), was designed to enhance the protective efficacy of BCG. We aimed to assess safety, immunogenicity, and efficacy of MVA85A against tuberculosis and Mycobacterium tuberculosis infection in infants. METHODS: In our double-blind, randomised, placebo-controlled phase 2b trial, we enrolled healthy infants (aged 4­6 months) without HIV infection who had previously received BCG vaccination. We randomly allocated infants (1:1), according to an independently generated sequence with block sizes of four, to receive one intradermal dose of MVA85A or an equal volume of Candida skin test antigen as placebo at a clinical facility in a rural region near Cape Town, South Africa. We actively followed up infants every 3 months for up to 37 months. The primary study outcome was safety (incidence of adverse and serious adverse events) in all vaccinated participants, but we also assessed efficacy in a protocol-defined group of participants who received at least one dose of allocated vaccine. The primary efficacy endpoint was incident tuberculosis incorporating microbiological, radiological, and clinical criteria, and the secondary efficacy endpoint was M tuberculosis infection according to QuantiFERON TB Gold In-tube conversion (Cellestis, Australia). This trial was registered with the South African National Clinical Trials Register (DOH-27-0109-2654) and with ClinicalTrials.gov on July 31, 2009, number NCT00953927. FINDINGS: Between July 15, 2009, and May 4, 2011, we enrolled 2797 infants (1399 allocated MVA85A and 1398 allocated placebo). Median follow-up in the per-protocol population was 24·6 months (IQR 19·2­28·1), and did not differ between groups. More infants who received MVA85A than controls had at least one local adverse event (1251 [89%] of 1399 MVA85A recipients and 628 [45%] of 1396 controls who received the allocated intervention) but the numbers of infants with systemic adverse events (1120 [80%] and 1059 [76%]) or serious adverse events (257 [18%] and 258 (18%) did not differ between groups. None of the 648 serious adverse events in these 515 infants was related to MVA85A. 32 (2%) of 1399 MVA85A recipients met the primary efficacy endpoint (tuberculosis incidence of 1·15 per 100 person-years [95% CI 0·79 to 1·62]; with conversion in 178 [13%] of 1398 infants [95% CI 11·0 to 14·6]) as did 39 (3%) of 1395 controls (1·39 per 100 person-years [1·00 to 1·91]; with conversion in 171 [12%] of 1394 infants [10·6 to 14·1]). Efficacy against tuberculosis was 17·3% (95% CI −31·9 to 48·2) and against M tuberculosis infection was −3·8% (­28·1 to 15·9). INTERPRETATION: MVA85A was well tolerated and induced modest cell-mediated immune responses. Reasons for the absence of MVA85A efficacy against tuberculosis or M tuberculosis infection in infants need exploration. FUNDING: Aeras, Wellcome Trust, and Oxford-Emergent Tuberculosis Consortium (OETC).