No evidence of durable trained immunity after two doses of adenovirus-vectored or mRNA COVID-19 vaccines

Bacille Calmette-Guérin (BCG) vaccine has immunomodulatory effects that may provide protection against unrelated infectious diseases. We aimed to determine whether BCG vaccination protects adults against COVID-19. Phase III double-blind randomised controlled trial. Healthcare centres in Australia, Brazil, the Netherlands, Spain, and the United Kingdom during the COVID-19 pandemic. 3988 healthcare workers with no prior COVID-19 and no contraindication to BCG. Randomised 1:1 using a web-based procedure to receive a single 0.1 mL intradermal dose of BCG-Denmark (BCG group, n = 1999) or saline (placebo group, n = 1989). Difference in incidence of (i) symptomatic and (ii) severe COVID-19 during the 12 months following randomisation in the modified intention to treat (mITT) population (confirmed SARS-CoV-2 naïve at inclusion). Of the 3988 participants randomised, 3386 had a negative baseline SARS-CoV-2 test and were included in the mITT population. The 12-month adjusted estimated risk of symptomatic COVID-19 was higher in the BCG group (22.6%; 95% confidence interval [CI] 20.6 to 24.5%) compared with the placebo group (19.6%; 95% CI 17.6 to 21.5%); adjusted difference +3.0% points (95% CI 0.2 to 5.8%; p = 0.04). The 12-month adjusted estimated risk of severe COVID-19 (mainly comprising those reporting being unable to work for ≥3 consecutive days) was 11.0% in the BCG group (95% CI 9.5 to 12.4%) compared with 9.6% in the placebo group (95% CI 8.3 to 11.1%); adjusted difference +1.3% points (95% CI -0.7 to 3.3%, p = 0.2). Breakthrough COVID-19 (post COVID-19 vaccination) and asymptomatic SARS-CoV-2 infections were similar in the two groups. There were 18 hospitalisations due to COVID-19 (11 in BCG group, 7 in placebo group; adjusted hazard ratio 1.56, 95% CI 0.60 to 4.02, p = 0.4) and two deaths due to COVID-19, both in the placebo group. Compared to placebo, vaccination with BCG-Denmark increased the risk of symptomatic COVID-19 over 12 months among healthcare workers and did not decrease the risk of severe COVID-19 or post-vaccination breakthrough COVID-19. ClinicalTrials.gov NCT04327206.

Background: Tuberculosis (TB) and diabetes mellitus (DM) comorbidity (TB-DM) presents a significant global health challenge, with diabetes increasing susceptibility to TB, worsening clinical outcomes, and impairing immune responses. Among these dysfunctions, macrophages—the primary immune cells responsible for pathogen recognition, phagocytosis, and bacterial clearance—exhibit profound alterations in TB-DM. However, the complex interplay between metabolic dysregulation, immune impairment, and macrophage dysfunction remains poorly defined. Objective: This scoping review systematically maps the literature on macrophage dysfunction in TB-DM, identifying key immunological impairments affecting phagocytosis, cytokine production, antigen presentation, macrophage polarisation, reactive oxygen species (ROS) and nitric oxide (NO) regulation, and chronic inflammation. Methods: A systematic search was conducted in PubMed, Web of Science, and Embase, covering studies from 2014 to 2024. Inclusion criteria focused on human studies investigating macrophage-specific mechanisms in TB-DM. Data extraction and synthesis were performed using Covidence, with findings grouped into key immunological themes. Results: A total of 44 studies were included, revealing significant impairments in macrophage function in TB-DM. Findings indicate reduced NO production, variable ROS dysregulation, altered M1/M2 polarisation, defective antigen presentation, and chronic inflammation. Elevated IL-10 and VEGF were associated with immune suppression and granuloma destabilisation, while eicosanoids (PGE2, LXA4) contributed to sustained inflammation. Conclusions: Macrophage dysfunction emerges as a central driver of immune failure in TB-DM, creating a self-perpetuating cycle of inflammation, immune exhaustion, and bacterial persistence. Understanding these mechanisms is essential for developing biomarker-driven diagnostics, host-directed therapies, targeted immunomodulation, and improving TB outcomes in diabetic populations. Future research should explore macrophage-targeted interventions to enhance immune function and mitigate TB-DM burden.

Some individuals have a persistence of symptoms following both COVID-19 (post-acute COVID-19 syndrome; PACS) and other viral infections. This study used prospectively collected data from an international trial to compare symptoms following COVID-19 and non-COVID-19 respiratory illness, to identify factors associated with the risk of PACS, and to explore symptom patterns before and after COVID-19 and non-COVID-19 respiratory illnesses. Data from a multicentre randomised controlled trial (BRACE trial) involving healthcare workers across four countries were analysed. Symptom data were prospectively collected over 12 months, allowing detailed characterisation of symptom patterns. Participants with COVID-19 and non-COVID-19 respiratory illness episodes were compared, focussing on symptom severity, duration (including PACS using NICE and WHO definitions), and pre-existing symptoms. Compared to those with a non-COVID-19 illness, participants with COVID-19 had significantly more severe illness (OR 7·4, 95%CI 5·6-9·7). Symptom duration meeting PACS definitions occurred in a higher proportion of COVID-19 cases than non-COVID-19 respiratory controls using both the NICE definition (2·5% vs 0·5%, OR 6·6, 95%CI 2·4-18·3) and the WHO definition (8·8% vs 3·7%, OR 2·5, 95%CI 1·4-4·3). When considering only participants with COVID-19, age 40-59 years (aOR 2·8, 95%CI 1·3-6·2), chronic respiratory disease (aOR 5·5, 95%CI 1·3-23·1), and pre-existing symptoms (aOR 3·0, 95%CI 1·4-6·3) were associated with an increased risk of developing PACS. Symptoms associated with PACS were also reported by participants in the months preceding their COVID-19 or non-COVID-19 respiratory illnesses (32% fatigue and muscle ache, 11% intermittent cough and shortness of breath). Healthcare workers with COVID-19 were more likely to have severe and longer-lasting symptoms than those with a non-COVID-19 respiratory illness, with a higher proportion meeting the WHO or NICE definitions of PACS. Age, chronic respiratory disease, and pre-existing symptoms increased the risk of developing PACS following COVID-19.

Background: The BCG vaccine has long been hypothesised to have non-specific protective effects, and early epidemiological studies on COVID-19 suggested a possible protective effect against SARS-CoV-2 infection and COVID-19 severity. This systematic review and meta-analysis assesses the effect of the BCG vaccine on preventing severe COVID-19 disease, based on the rate of hospitalisation for COVID-19 related disease. Methods: We performed a literature search of randomised control trials comparing BCG vaccine to placebo in adult participants using EMBASE, MEDLINE, and Web of Science. A random effects model was used to generate summary estimates. Risk of bias was assessed regarding randomisation, allocation sequence concealment, blinding, incomplete outcome data, selective outcome reporting, and other biases. Results: We included 11 studies involving 18,412 participants, reporting COVID-19 incidence. The hospitalisation rate was sought from the authors of papers that did not report on this statistic. There was no significant reduction in COVID-19-related hospitalisation across all studies (relative risk 0.85, 0.51–1.40, p = 0.335), COVID-19 incidence across all studies (relative risk 1.07, 0.94–1.21, p = 0.264), deaths reported in six studies (relative risk 0.67, 0.36–1.26, p = 0.733), and COVID-19-related critical care admissions reported in four studies (relative risk 0.43, 0.13–1.46, p = 0.746). Conclusions: The findings from this meta-analysis, involving a large number of participants, suggest no protective effect of BCG vaccination against severe COVID-19 outcomes or overall SARS-CoV-2 incidence. Further research may be needed to explore the potential non-specific effects of BCG vaccination in other specific populations and against other infections.

Asphyxiating thoracic dystrophy (ATD), also known as Jeune syndrome, is a rare autosomal recessive chondrodysplasia that most commonly manifests as shortening of long bones and ribs, as well as frequent extra‐skeletal organ involvement. It is typically diagnosed in infancy or early childhood following episodes of respiratory distress or failure, in conjunction with characteristic physical findings, and is often fatal. The genetic heterogeneity of this disease, however, means there is varying severity of symptoms and physical manifestations. In this report, we describe a 57‐year‐old man with his first presentation of respiratory failure, with a history and physical findings consistent with ATD, a diagnosis previously unknown to the patient.