Randomized Trial of BCG Vaccine to Protect against Covid-19 in Health Care Workers.

BACKGROUND: The bacille Calmette-Guérin (BCG) vaccine has immunomodulatory "off-target" effects that have been hypothesized to protect against coronavirus disease 2019 (Covid-19). METHODS: In this international, double-blind, placebo-controlled trial, we randomly assigned health care workers to receive the BCG-Denmark vaccine or saline placebo and followed them for 12 months. Symptomatic Covid-19 and severe Covid-19, the primary outcomes, were assessed at 6 months; the primary analyses involved the modified intention-to-treat population, which was restricted to participants with a negative test for severe acute respiratory syndrome coronavirus 2 at baseline. RESULTS: A total of 3988 participants underwent randomization; recruitment ceased before the planned sample size was reached owing to the availability of Covid-19 vaccines. The modified intention-to-treat population included 84.9% of the participants who underwent randomization: 1703 in the BCG group and 1683 in the placebo group. The estimated risk of symptomatic Covid-19 by 6 months was 14.7% in the BCG group and 12.3% in the placebo group (risk difference, 2.4 percentage points; 95% confidence interval [CI], -0.7 to 5.5; P = 0.13). The risk of severe Covid-19 by 6 months was 7.6% in the BCG group and 6.5% in the placebo group (risk difference, 1.1 percentage points; 95% CI, -1.2 to 3.5; P = 0.34); the majority of participants who met the trial definition of severe Covid-19 were not hospitalized but were unable to work for at least 3 consecutive days. In supplementary and sensitivity analyses that used less conservative censoring rules, the risk differences were similar but the confidence intervals were narrower. There were five hospitalizations due to Covid-19 in each group (including one death in the placebo group). The hazard ratio for any Covid-19 episode in the BCG group as compared with the placebo group was 1.23 (95% CI, 0.96 to 1.59). No safety concerns were identified. CONCLUSIONS: Vaccination with BCG-Denmark did not result in a lower risk of Covid-19 among health care workers than placebo. (Funded by the Bill and Melinda Gates Foundation and others; BRACE ClinicalTrials.gov number, NCT04327206.).

BCG-induced trained immunity: history, mechanisms and potential applications.

The Bacillus Calmette-Guérin (BCG) vaccine was discovered a century ago and has since been clinically applicable. BCG can not only be used for the prevention of tuberculosis, but also has a non-specific protective effect on the human body called trained immunity that is mediated by innate immune cells such as monocytes, macrophages, and natural killer cells. Mechanisms of trained immunity include epigenetic reprogramming, metabolic reprogramming, and long-term protection mediated by hematopoietic stem cells. Trained immunity has so far shown beneficial effects on cancer, viral-infections, autoimmune diseases, and a variety of other diseases, especially bladder cancer, respiratory viruses, and type 1 diabetes. The modulation of the immune response by BCG has led to the development of a variety of recombinant vaccines. Although the specific mechanism of BCG prevention on diseases has not been fully clarified, the potential role of BCG deserves further exploration, which is of great significance for prevention and treatment of diseases.

Effects of intravesical BCG maintenance therapy duration on recurrence rate in high-risk non-muscle invasive bladder cancer (NMIBC): Systematic review and network meta-analysis according to EAU COVID-19 recommendations.

PURPOSE: During the coronavirus disease 2019 (COVID-19) pandemic, the European Association of Urology (EAU) recommended that courses of intravesical bacillus Calmette-Guérin (BCG) therapy lasting more than 1 year could be safely terminated for patients with high-risk non-muscle-invasive bladder cancer (NMIBC). Thus, we conducted a systematic review and network meta-analysis according to EAU's COVID-19 recommendations. MATERIALS AND METHODS: A systematic review was performed following the Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines. We conducted a network meta-analysis of recurrence rate in patients with NMIBC receiving induction therapy (M0) and those receiving maintenance therapy lasting 1 year (M1) and more than 1 year (M2). RESULTS: Nineteen studies of 3,957 patients were included for the network meta-analysis. In a node-split forest plot using Bayesian Markov Chain Monte Carlo (MCMC) modeling, there were no differences between the M1 and M2 groups in recurrence rate [odds ratio (OR) 0.95 (0.73-1.2)]. However, recurrence rate in the M0 group was higher than that in the M1 [OR 1.9 (1.5-2.5)] and M2 [OR 2.0 (1.7-2.4)] groups. P-score tests using frequentist inference to rank the treatments in the network demonstrated that the therapy used in the M2 group (P-score 0.8701) was superior to that used in the M1 (P-score 0.6299) and M0 groups (P-score 0). In rank-probability tests using MCMC modeling, the M2 group showed the highest rank, followed by the M1 and M0 groups. CONCLUSION: In the network meta-analysis, there were no differences between those receiving BCG maintenance therapies in terms of recurrence rate. In the rank tests, therapy lasting more than 1-year appears to be most effective. During the COVID-19 pandemic, 1-year maintenance therapy can be used, but after the COVID-19 pandemic, therapy lasting more than 1-year could be beneficial.

Comparing Bacillus Calmette-Guérin (BCG) strains in convalescent COVID-19 patients.

Aim: We previously published results of the BATTLE trial, showing that patients recently infected with SARS-CoV-2 can benefit from receiving Bacillus Calmette-Guérin (BCG) with minimal adverse effects. The study incorporated two strains of this vaccine. In this study, patient outcomes were compared based on the strain of BCG because different strains have been shown to have different immunogenicity. Methods: BATTLE was a double-blind controlled trial of COVID-19 convalescent patients; symptom progression, injection-site lesion characteristics and adverse effects were compared between recipients of placebo, Russian BCG strain or Brazilian BCG strains. Results: There was no statistically significant difference between the two BCG strains in terms of symptom progression, lesion-size or type. Conclusion: The two strains have similar clinical outcomes in COVID-19 convalescent patients.

We previously published results of the BATTLE trial, showing that patients recently infected with SARS-CoV-2 virus can benefit from receiving BCG with minimal adverse effects. This article shows that the two BCG strains, Russian and Brazilian, have similar clinical outcomes in COVID-19 convalescent patients.

Association between presence of Bacillus Calmette-Guerin vaccine scar and coronavirus disease 2019.

Bacillus Calmette-Guerin vaccine is administered for protection against tuberculosis and may also have beneficial effects against some viral respiratory tract infections. In this study, it was aimed to investigate the relationship between Bacillus Calmette-Guerin vaccination which is confirmed by BCG scar, and the frequency and course of Coronavirus disease 2019 (COVID-19). Among 490 patients, 400 patients who accepted to participate in the study were included. After the consent of patients, age, gender, body mass index, comorbidities, smoking, history, and the progress of COVID-19 of these patients were investigated; the presence and number of Bacillus Calmette-Guerin scars were recorded by a physician. Data from groups with and without COVID-19 history were compared. There was no relation between presence and number of the BCG scar and COVID-19 related hospitalization and intensive care unit admission. When groups with and without COVID-19 history compared, no statistically significant difference was found with the presence and number of Bacillus Calmette-Guerin scars (P > 0,05). No association was found between the presence or number of BCG scars and the frequency and course of COVID-19 in individuals with Bacillus Calmette-Guerin vaccination history confirmed by the presence of Bacillus Calmette-Guerin vaccine scars. Currently, the most important protection against COVID-19 is the COVID-19 vaccine.

Multiple BCG vaccinations for the prevention of COVID-19 and other infectious diseases in type 1 diabetes.

There is a need for safe and effective platform vaccines to protect against coronavirus disease 2019 (COVID-19) and other infectious diseases. In this randomized, double-blinded, placebo-controlled phase 2/3 trial, we evaluate the safety and efficacy of a multi-dose Bacillus Calmette-Guérin (BCG) vaccine for the prevention of COVID-19 and other infectious disease in a COVID-19-unvaccinated, at-risk-community-based cohort. The at-risk population is made of up of adults with type 1 diabetes. We enrolled 144 subjects and randomized 96 to BCG and 48 to placebo. There were no dropouts over the 15-month trial. A cumulative incidence of 12.5% of placebo-treated and 1% of BCG-treated participants meets criteria for confirmed COVID-19, yielding an efficacy of 92%. The BCG group also displayed fewer infectious disease symptoms and lesser severity and fewer infectious disease events per patient, including COVID-19. There were no BCG-related systemic adverse events. BCG's broad-based infection protection suggests that it may provide platform protection against new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants and other pathogens.

Revisiting the potential role of BCG and MMR vaccines in COVID-19.

Despite the development and deployment of effective COVID-19 vaccines, many regions remain poorly covered. Seeking alternative tools for achieving immunity against COVID-19 remains to be of high importance. "Trained immunity" is the nonspecific immune response usually established through administering live attenuated vaccines and is a potential preventive tool against unrelated infections. Evidence regarding a possible protective role for certain live attenuated vaccines against COVID-19 has emerged mainly for those administered as part of childhood vaccination protocols. This review summarizes the relevant literature about the potential impact of Bacille Calmette-Guérin (BCG) and measles, mumps and rubella (MMR) vaccines on COVID-19. Existing available data suggest a potential role for BCG and MMR in reducing COVID-19 casualties and burden. However, more investigation and comparative studies are required for a better understanding of their impact on COVID-19 outcomes.

BCG vaccine safety in COVID-19 convalescent adults: BATTLE a randomized controlled trial.

INTRODUCTION: The safety of BCG revaccination is uncertain and there is no data on its use in patients with COVID-19. METHODS: COVID-19 convalescent adults confirmed by SARS-CoV-2 RT-PCR in South-America were 1:1 randomized in the first 14 days of symptoms to BCG intradermal vaccine or placebo and evaluated for adverse events on days 7, 14, 21, and beyond 40 days. CLINICAL TRIAL REGISTRATION: NCT04369794. RESULTS: 151 placebo and 148 BCG patients were included in the final analysis, with an average age of 40.7 years. No severe adverse event to BCG was reported. On day 7, 130 (87.8%) of the BCG recipients had local reaction, average size of 10.6 ± 6.4 mm, compared to only 2 (1.3%) placebos. Lesions gradually shrunk in size (mean 10.5 mm, 9.7 mm, and 6.8 mm at 14, 21, and beyond 40 days, respectively. The number of symptoms in any of the visits was not different between groups, and anosmia resolved earlier (25.7% vs. 37.1% at 7 days, OR = 1.70, 1.01-2.89, p = 0.035) in the BCG recipients. CONCLUSION: The BCG revaccination is safe in convalescent COVID-19 adults of a tuberculosis endemic region, regardless of tuberculin or IGRA test results. Local adverse events were similar though occurred earlier to that previously reported in children.

The Potential Roles of BCG Vaccine in the Prevention or Treatment of COVID-19.

Coronavirus disease 2019 (COVID-19), which broke out at the end of 2019, is a global pandemic and seriously threatens human health. Vaccination is the most effective way to prevent and control COVID-19. At present, more than 13 COVID-19 vaccines have been urgently authorized for use, but the emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants has brought unprecedented challenges to the protective efficiency of these COVID-19 vaccines. In particular, the recent emergence of Delta and Omicron variants, which are rapidly spreading worldwide, may bring many challenges to the medical systems. Interestingly, previous studies have shown that the Bacillus Calmette-Guerin (BCG) vaccine used to prevent tuberculosis can induce non-specific trained immunity, protecting against infectious diseases caused by respiratory viruses. Therefore, there is a hypothesis that BCG plays an essential role in reducing the incidence, severity, hospitalization, and mortality of COVID-19 and enhancing the protection efficiency of the COVID-19 vaccine. To confirm this hypothesis, 56 clinical trials have been conducted globally to assess BCG's protective effectiveness against COVID-19 infection. Herein, this review discussed the trained immunity induced by BCG and its underlying mechanisms and summarised BCG's latest research progress in preventing COVID-19, especially the ongoing clinical trials. We hope this review will provide new strategies for fighting against COVID-19.

Tuberculosis vaccines in the era of Covid-19 - what is taking us so long?

The Mycobacterium bovis BCG vaccine was first used in 1921, but has not controlled the global spread of tuberculosis (TB). There are still no new licensed tuberculosis vaccines, although there much active research and a vaccine development pipeline, with vaccines designed to prevent infection, prevent disease, or accelerate TB treatment. These vaccines are of different types, and designed to replace BCG, or to boost immunity following BCG vaccination. This viewpoint discusses why, when it has been possible to develop new vaccines for SARS-CoV-2 so quickly, it is taking so long to develop new tuberculosis vaccines.

Safety and Optimal Timing of BCG Vaccination in Infants Born to Mothers Receiving Anti-TNF Therapy for Inflammatory Bowel Disease.

BACKGROUNDS AND AIMS: We aimed to evaluate the safety of Bacille Calmette-Guérin [BCG] vaccination in infants born to mothers receiving anti-tumour necrosis factor [anti-TNF] therapy for inflammatory bowel disease. METHODS: Adverse events of BCG vaccination were evaluated in 90 infants who were last exposed to anti-TNF agents at a median of gestational week 30. RESULTS: After receiving BCG vaccination at a median age of 6 months [range, 0.25-11 months], three infants [3.3%] showed injection site swelling, two of whom also showed axillar lymphadenopathy. The rates of adverse events were similar between infants who were last exposed to anti-TNF agents before the third trimester [n = 35] and those who were last exposed in the third trimester [n = 55] [2.9% vs 3.6%; p = 1.00]. All adverse events were spontaneously resolved and there were no serious adverse events such as active tuberculosis infection or death. CONCLUSIONS: BCG vaccination after 6 months of age is of low risk in infants exposed to anti-TNF agents in utero.

Cheap and Commonplace: Making the Case for BCG and γδ T Cells in COVID-19.

Antigen-specific vaccines developed for the COVID-19 pandemic demonstrate a remarkable achievement and are currently being used in high income countries with much success. However, new SARS-CoV-2 variants are threatening this success via mutations that lessen the efficacy of antigen-specific antibodies. One simple approach to assisting with this issue is focusing on strategies that build on the non-specific protection afforded by the innate immune response. The BCG vaccine has been shown to provide broad protection beyond tuberculosis disease, including against respiratory viruses, and ongoing studies are investigating its efficacy as a tool against SARS-CoV-2. Gamma delta (γδ) T cells, particularly the Vδ2 subtype, undergo rapid expansion after BCG vaccination due to MHC-independent mechanisms. Consequently, γδ T cells can produce diverse defenses against virally infected cells, including direct cytotoxicity, death receptor ligands, and pro-inflammatory cytokines. They can also assist in stimulating the adaptive immune system. BCG is affordable, commonplace and non-specific, and therefore could be a useful tool to initiate innate protection against new SARS-CoV-2 variants. However, considerations must also be made to BCG vaccine supply and the prioritization of countries where it is most needed to combat tuberculosis first and foremost.

Candidate immunomodulators for COVID-19: Heat-killed Mycobacterium w and BCG vaccine.

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Heterologous vaccine interventions: boosting immunity against future pandemics.

While vaccines traditionally have been designed and used for protection against infection or disease caused by one specific pathogen, there are known off-target effects from vaccines that can impact infection from unrelated pathogens. The best-known non-specific effects from an unrelated or heterologous vaccine are from the use of the Bacillus Calmette-Guérin (BCG) vaccine, mediated partly through trained immunity. Other vaccines have similar heterologous effects. This review covers molecular mechanisms behind the heterologous effects, and the potential use of heterologous vaccination in the current COVID-19 pandemic. We then discuss novel pandemic response strategies based on rapidly deployed, widespread heterologous vaccination to boost population-level immunity for initial, partial protection against infection and/or clinical disease, while specific vaccines are developed.