Tuberculin reaction and BCG scar: association with infant mortality

Non-specific protection against severe COVID-19 associated to typhoid fever and DTP vaccination

Trained immunity (TRAIM) or the enhanced non-specific immune response after primary stimulation by infection or vaccination is a recent but well-recognized concept. To verify its predictions, our objective was to determine the effects of two bacterial vaccines, typhoid fever (TFV) and diphtheria-tetanus-pertussis (DTP) on the infection, hospitalization and death frequencies associated to COVID-19 in a retrospective study on subjects vaccinated or not with TFV and DTP in the 4 years prior to the start of COVID-19 pandemia in the Basque Country (Spain). The studied outcome records were split into two periods according to COVID-19 vaccination, the pre-vaccination (ACV) from March to December 2020 and the post-vaccination (PCV) from September 2021 to June 2022). In total, 13,673 subjects were vaccinated against TFV and 42,997 against DTP. A total of 2,005,084 individual records were studied in the ACV period and 1,436,693 in the PCV period. The proportion of infection, hospitalization and death associated to COVID-19 among controls in ACV was 4.97 %, 7.14 % and 3.54 %, respectively vs. 7.20 %, 2.24 % and 0.10 % among TFV subjects. Regarding DTP, the proportions were 4.97 %, 7.12 % and 3.58 % for controls and 5.79 %, 5.79 % and 0.80 % for vaccinees. In the PCV period, the proportion of infection, hospitalization and death among controls was 21.89 %, 2.62 % and 0.92 %, respectively vs. 31.19 %, 0.76 %, 0.00 % among TFV. For DTP, infection, hospitalization and death proportions were 21.89 %, 2.62 % and 0.92 %, respectively, among controls vs. 32.03 %, 1.85 % and 0.24 % among vaccinated subjects. The corresponding combined ACV and PCV odds ratios (OR) for SARS-CoV2 infection were 1.505 (95%CI 1.455-1.558; p < 0.0001; reduction -41.85 %) and 1.633 (95%CI 1.603-1.662; p < 0.0001; reduction -51.74 %), for TFV and DTP, respectively. Regarding COVID-19 associated hospitalization, the OR were 0.295 (95%CI 0.220-0.396; p = 0.0001; reduction 69.74 %) and 0.667 (95%CI 0.601-0.741; p = 0.0001; reduction 32.44 %), for TFV and DTP, respectively). COVID-19 associated death OR were 0.016 (95%CI 0.002-0.113, p < 0.0001; reduction 98.38 %) and 0.212 (95%CI 0.161-0.280; p = 0.0001; reduction 78.52 %), for TFV and DTP, respectively. We conclude that TRAIM effects by TFV and DTP vaccination in the four years prior to the pandemic SARS-CoV2 were supported by slightly increased infection rates, but strongly reduced COVID-19 associated hospitalization and death rates.

Using real-life data to model the impact of increasing BCG vaccination coverage and scar prevalence on all-cause infant mortality

PURPOSE

Estimating the potential impact on infant mortality of increasing Bacille Calmette-Guérin (BCG) vaccination coverage and BCG scar prevalence.

METHODS

Guinea-Bissau Health and Demographic Surveillance System data on BCG vaccination coverage, scar status, and all-cause mortality were used for this study. Mortality risk (MR) by scar status was assessed in Cox models providing adjusted mortality rate ratios (aMRRs). Distributions were fitted for survival, vaccination coverage, and scar prevalence. Models for 12-month mortality were calculated. We utilized World Bank data on birth rates and mortality rates to assess the potential global impact of optimizing BCG vaccination programs.

RESULTS

BCG coverage was 81% and scar prevalence 42% among 2-month-old infants, and the 1- to 12-month scar/no scar aMRR was 0.40 (0.22, 0.76). Modeling 2-month 99% vaccination coverage with 95% developing scars would change the 1- to 12-month MR by -8% (-21%, +12%). Globally, the reduction in the MR between 1- and 12-month would be -14% (-14%, -15%), corresponding to -208,075 (-214,453, -204,023) fewer infant deaths/year.

CONCLUSIONS

We confirmed previous observations: having a BCG scar markedly reduces infant MR. Increasing current global 2-month BCG vaccination coverage from 76% to 99%, and scar prevalence among vaccinated infants from 52% to 95% might reduce global infant mortality by >200,000 deaths/year. Thus, optimizing BCG vaccination programs to focus on increasing early BCG vaccination coverage and the overall scar prevalence would have major public health benefits.

Erratum: Factors influencing scar formation following Bacille Calmette-Guérin (BCG) vaccination

[This corrects the article DOI: 10.1016/j.heliyon.2023.e15241.].

Factors influencing scar formation following Bacille Calmette-Guérin (BCG) vaccination

The prevalence of scar formation following Bacille Calmette-Guérin (BCG) vaccination varies globally. The beneficial off-target effects of BCG are proposed to be stronger amongst children who develop a BCG scar. Within an international randomised trial ('BCG vaccination to reduce the impact of coronavirus disease 2019 (COVID-19) in healthcare workers'; BRACE Trial), this nested prospective cohort study assessed the prevalence of and factors influencing scar formation, as well as participant perception of BCG scarring 12 months following vaccination . Amongst 3071 BCG-recipients, 2341 (76%) developed a BCG scar. Scar prevalence was lowest in Spain and highest in UK. Absence of post-injection wheal (OR 0.4, 95%CI 0.2-0.9), BCG revaccination (OR 1.7, 95%CI 1.3-2.0), female sex (OR 2.0, 95%CI 1.7-2.4), older age (OR 0.4, 95%CI 0.4-0.5) and study country (Brazil OR 1.6, 95%CI 1.3-2.0) influenced BCG scar prevalence. Of the 2341 participants with a BCG scar, 1806 (77%) did not mind having the scar. Participants more likely to not mind were those in Brazil, males and those with a prior BCG vaccination history. The majority (96%) did not regret having the vaccine. Both vaccination-related (amenable to optimisation) and individual-related factors affected BCG scar prevalence 12 months following BCG vaccination of adults, with implications for maximising the effectiveness of BCG vaccination.

COVID-19 and Beyond: Exploring Public Health Benefits from Non-Specific Effects of BCG Vaccination

Bacille Calmette–Guérin (BCG) vaccination, widely used throughout the world to protect against infant tuberculous meningitis and miliary tuberculosis (TB), can provide broad non-specific protection against infectious respiratory diseases in certain groups. Interest in BCG has seen a resurgence within the scientific community as the mechanisms for non-specific protection have begun to be elucidated. The impact of the COVID-19 pandemic on nearly every aspect of society has profoundly illustrated the pressure that respiratory infections can place on a national healthcare system, further renewing interest in BCG vaccination as a public health policy to reduce the burden of those illnesses. However, the United States does not recommend BCG vaccination due to its variable effectiveness against adult TB, the relatively low risk of Mycobacterium tuberculosis infection in most of the United States, and the vaccine’s interference with tuberculin skin test reactivity that complicates TB screening. In this review, we explore the broad immune training effects of BCG vaccination and literature on the effects of BCG vaccination on COVID-19 spread, disease severity, and mortality. We further discuss barriers to scheduled BCG vaccination in the United States and how those barriers could potentially be overcome.

Neonatal Bacille Calmette-Guérin vaccination and tuberculin skin test reactions at 2- and 6-months: Effects on mortality up to 1 year of age

BACKGROUND

In randomized trials, Bacille Calmette-Guérin (BCG) vaccine has been associated with reduced all-cause mortality. BCG-induced Tuberculin Skin Test (TST) reactions have also been associated with reduced all-cause mortality. We aimed to assess the association between TST responses and subsequent mortality in three birth cohorts and conducted a meta-analysis of existing studies.

METHODS

Observational study within three Guinea-Bissau BCG trial birth cohorts (conducted 2002-04, 2009-2013 and 2014-18) that encompassed children who were BCG-vaccinated within 28 days with TSTs performed at 2- (n = 1389) and 6-months (n = 2635) of age. We evaluated TST reaction determinants by binomial regression and assessed the association between TSTs > 1 mm (reactors) vs. ≤ 1 mm (non-reactors) and subsequent mortality risk up to age 12 months in Cox-models providing Mortality Rate Ratios (MRRs). We searched PubMed for studies to calculate meta-estimates of the association between TST reactivity by age 2- and 6-months and all-cause mortality.

RESULTS

Large post-vaccination wheal size was associated with 6-month TST positivity and so was receiving BCG-Denmark or BCG-Japan, compared with BCG-Russia. By age 2 months, 22% (302/1389) of infants were TST reactors with a 2-12-month mortality risk of 1.7% (5/302) vs. 3.3% (36/1087) for non-reactors, the corresponding reactor/non-reactor MRR = 0.49 (0.19-1.26). By age 6 months, 44% (1149/2635) of infants were reactors and the 6-12-month mortality risk was 0.4% (4/1149) vs. 0.6% (9/1486) for non-reactors, the MRR = 0.87 (0.27-2.86). The literature search provided 3 studies. The meta-analysis revealed a uniform pattern of reduced mortality associated with TST reactivity, a TST response by 2 months being associated with an MRR of 0.59 (0.39-0.90); for 6-month TST responses the MRR was 0.65 (0.43-1.00).

CONCLUSION

Among BCG-vaccinated infants, TST reactions were associated with markedly reduced mortality. Improved vaccination technique and using certain BCG strains could lead to a higher TST reaction prevalence, which would enhance BCG's beneficial non-specific effects.

BCG skin reactions by 2 months of age are associated with better survival in infancy: a prospective observational study from Guinea-Bissau

Introduction

Receiving Bacille Calmette-Guérin (BCG)-Denmark vaccine at birth has been associated with ~40% reductions in all-cause neonatal mortality. We evaluated determinants of BCG skin reaction characteristics by age 2 months and tested the association with subsequent mortality.

Methods

Prospective observational study amalgamating five trials providing BCG-at-birth that were conducted between 2002 and 2018 in Guinea-Bissau. The reaction status and size were evaluated at home-visits by 2 months of age among 6012 neonates; mortality from 2 to 12 months was assessed at subsequent visits. Reaction determinants were evaluated by binomial regression providing risk ratios (RRs). In Cox-models providing adjusted mortality rate ratios (aMRRs), we assessed the association between (1) having a 2-month reaction (yes/no) and (2) reaction size tertiles and subsequent all-cause mortality risk. A subgroup had their BCG reaction evaluated and were bled at age 4 weeks; their samples underwent in vitro analysis for specific and non-specific cytokine responses.

Results

The BCG strain was the main determinant for developing a 2-month reaction and the reaction size: the BCG-Russia/BCG-Denmark RR for large-reaction was 0.38 (0.30–0.47) and the BCG-Russia/BCG-Japan RR was 0.61 (0.51–0.72). 5804 infants (96.5%) were reactors by age 2 months; 208 (3.5%) were non-reactors. The 2–12 months mortality risk was 4.8% (10/208) for non-reactors, 2.9% (64/2213) for small reactors, 1.8% (30/1710) for medium reactors and 0.8% (15/1881) for large reactors. The reactor/non-reactor aMRR was 0.49 (0.26–0.95) and there was a linear trend of decreasing mortality with increasing reaction size (p for trend <0.001). BCG reactors had higher 4-week specific and non-specific cytokine responses, responses that were highest among those with large reactions.

Conclusion

Among BCG-vaccinated infants, having a BCG skin reaction by age 2 months was associated with markedly better survival, as was the reaction size. Our findings thus support that BCG has substantial effects on all-cause mortality. Emphasising at-birth vaccination with immunogenic BCG strains and revaccinating non-reactors and small reactors could have major public health benefits.

Trial registration numbers

NCT00146302, NCT00168610, NCT00625482, NCT01989026 and NCT02447536.

Factors associated with birthweight and adverse pregnancy outcomes among children in rural Guinea-Bissau - a prospective observational study

Background

Low birthweight (LBW) is associated with higher mortality and morbidity, but there is limited data on the prevalence of LBW in rural Africa, where many births occur at home. The Bacillus Calmette-Guérin (BCG) vaccine has non-specific effects. Studies suggest that maternal BCG-vaccination may affect the health of the child.

Methods

The present study is nested within a randomised trial in rural Guinea-Bissau: Pregnancies were registered at two-monthly village visits, where information on BCG scar status and other background factors were obtained. Children were enrolled in the trial and weighed at home within 72 h after birth. In this prospective observational study, we assessed factors associated with adverse pregnancy outcomes and birthweight in binomial and linear regression models.

Results

Among 1320 women who had their BCG scar status assessed, 848 (64%) had a scar, 472 (36%) had no scar. The risk of adverse pregnancy outcomes (miscarriages, stillbirths, early neonatal deaths) tended to be higher among BCG scar-negative women (13%) than among women with a BCG scar (10%), adjusted prevalence ratio = 1.29 (0.99–1.68). Birthweight was assessed for 628 (50%) of the 1232 live born children. The mean birthweight was 2.89 kg (SD 0.43) and the proportion of LBW children was 17% (104/628). Sex, twinning, region of birth, maternal age, maternal mid-upper arm circumference (MUAC), antenatal consultations, parity and possession of a mobile phone were associated with birthweight, while maternal BCG scar status was not.

Conclusions

This study provides the first birthweight data for home-born children in rural Guinea-Bissau, with a mean birthweight of 2.89 kg (SD 0.43) and a LBW prevalence of 17%. We found a tendency for higher risk of adverse pregnancy outcomes among BCG scar-negative women. Birthweight was similar in children of mothers with and without BCG scar.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-11215-8.

Paratuberculosis vaccination specific and non-specific effects on cattle lifespan

Records of cattle vaccination against paratuberculosis (PTB) have been analyzed to determine whether or not non-specific effect (NSE) on overall mortality similar to that observed in BCG vaccinated humans occurs in animals. The results of a previously reported slaughterhouse study on PTB prevalence were used as a reference on the age incidence of advanced patent (clinical) epidemio-pathogenic forms. In the proper vaccine study, cows in 30 cattle farms in the Basque Country, Spain were followed-up for between 1 and 13 years. Vaccinated groups were composed by 1008 (592 right-censored) animals younger than 3 months treated as calves and by 3761 (3160 right-censored) vaccinated at any older age. Controls were 339 (157 right-censored) and 4592 (2213 right-censored) age matched animals, respectively. Individual last year presence in the annual testing was considered age at culling or death. A survival analysis was carried out according age at vaccination of vaccinated versus non-vaccinated animals. PTB age incidence in the slaughterhouse study was subtracted from the difference between vaccinated and non-vaccinated animals at the same age in order to estimate PTB-specific and non-specific effects. The maximum difference was observed at the 2-3 years interval with a 33.9% mortality reduction in the calf vaccinated group. This corresponded also with the maximum NSE that was 24.5% for a PTB incidence of 9.5%. Overall, vaccination afforded to calves a 26.5% yearly mortality protection, split between 11.1% PTB-specific and 15.4% NSE. These results support a NSE on total mortality associated with PTB vaccination that appeared to persist for up to 6-7 years. This confirms for the first time in an animal field study the innate immune system memory predicted by the recently proposed trained immunity theory. Contrasting the literature, no deleterious effects of killed vaccines on females were observed. Mortality reduction would offset vaccination costs and could improve livestock systems efficiency and potentially reduce antibiotic use. Clinical trial registered with Spanish Agency for Drugs and Sanitary products (AEMPS) as 11/012/ECV.

BCG scarring and improved child survival: a combined analysis of studies of BCG scarring

Bacillus Calmette-Guérin (BCG) vaccine against tuberculosis (TB) is recommended at birth in TB-endemic areas. Currently, BCG vaccination programmes use "BCG vaccination coverage by 12 months of age" as the performance indicator. Previous studies suggest that BCG-vaccinated children, who develop a scar, have better overall survival compared with BCG-vaccinated children, who do not develop a scar. We summarized the available studies of BCG scarring and child survival. A structured literature search for studies with original data and analysis of BCG scarring and mortality were performed. Combined analyses on the effect of BCG scarring on overall mortality. We identified six studies covering seven cohorts, all from Guinea-Bissau, West Africa, with evaluation of BCG scarring amongst BCG-vaccinated children and follow-up for mortality. Determinants of BCG scarring were BCG strain, intradermal injection route, size of injection wheal, and co-administered vaccines and micronutrients. In a combined analysis, having a BCG scar vs. no BCG scar was associated with a mortality rate ratio (MRR) of 0.61 (95% CI: 0.51-0.74). The proportion with a BCG scar varied from 52 to 93%; the estimated effect of a BCG scar was not associated with the scar prevalence. The effect was strongest in the first (MRR = 0.48 (0.37-0.62)) and second (MRR = 0.63 (0.44-0.92)) year of life, and in children BCG-vaccinated in the neonatal period (MRR = 0.45 (0.36-0.55)). The effect was not explained by protection against TB. Confounding and genetic factors are unlikely to explain the strong association between BCG scarring and subsequent survival. Including "BCG scar prevalence" as a BCG vaccination programme performance indicator should be considered. The effect of revaccinating scar-negative children should be studied.

Maternal Priming: Bacillus Calmette-Guérin (BCG) Vaccine Scarring in Mothers Enhances the Survival of Their Child With a BCG Vaccine Scar

BACKGROUND AND HYPOTHESIS

Maternal priming might enhance the beneficial nonspecific effects (NSEs) of live measles vaccination (MV). Children with a bacillus Calmette-Guérin (BCG) vaccine scar have a lower mortality rate than those without a scar that is not explained by protection against tuberculosis. We examined the hypothesis that BCG scarring would have a stronger effect on a child if the mother also had a BCG scar.

METHODS

In a randomized controlled trial (RCT) of early MV in children aged 4.5 months, the BCG-scar status of the children and their mother were registered at enrollment at 4.5 months of age. The children were followed up until they were 36 months of age. Using a Cox proportional hazards model, we compared mortality rate ratios according to maternal and child BCG-scar status after adjusting for where the BCG vaccine was given (the national hospital or elsewhere). We censored for other interventions that have immunomodulating effects on child survival, including neonatal vitamin A supplementation and early MV.

RESULTS

A total of 2213 children had not received neonatal vitamin A supplementation and early MV; 83% of these children and 44% of the mothers had a BCG scar. Children whose mother had a BCG scar were not more likely to have a BCG scar than those whose mother did not have a BCG scar (risk ratio, 1.01 [95% confidence interval (CI), 0.98-1.05]). Among the children, having a BCG scar was associated with a 41% (95% CI, 5%-64%) lower mortality between the ages of 4.5 and 36 months. The reduction in mortality was 66% (95% CI, 33%-83%) if the mother also had a BCG scar but only 8% (95% CI, -83% to 53%) if the mother had no BCG scar (test of interaction, P = .04).

CONCLUSIONS

Maternal BCG priming might be important for the effect of BCG vaccination on child survival. Ensuring better BCG vaccine scarring among mothers and children could have a considerable effect on child mortality levels.

BCG: a vaccine with multiple faces

BCG has been recommended because of its efficacy against disseminated and meningeal tuberculosis. The BCG vaccine has other mechanisms of action besides tuberculosis protection, with immunomodulatory properties that are now being discovered. Reports have shown a significant protective effect against leprosy. Randomized controlled trials suggest that BCG vaccine has beneficial heterologous (nonspecific) effects on mortality in some developing countries. BCG immunotherapy is considered the gold standard adjuvant treatment for non-muscle-invasive bladder cancer. BCG vaccine has also been tested as treatment for diabetes and multiple sclerosis. Erythema of the BCG site is recognized as a clinical clue in Kawasaki disease. BCG administration in the immunodeficient patient is associated with local BCG disease (BCGitis) or disseminated BCG disease (BCGosis) with fatal consequences. BCG administration has been associated with the development of autoimmunity. We present a brief review of the diverse facets of the vaccine, with the discovery of its new modes of action providing new perspectives on this old, multifaceted and controversial vaccine.

Early Vaccination With Bacille Calmette-Guérin-Denmark or BCG-Japan Versus BCG-Russia to Healthy Newborns in Guinea-Bissau: A Randomized Controlled Trial

Background

Bacille Calmette-Guérin (BCG) vaccination remains a cornerstone against tuberculosis. Randomized controlled trials (RCTs) have demonstrated that BCG-Denmark lowers all-cause mortality, but a recent RCT found no effect of BCG-Russia. Observational studies indicate that the genetically divergent BCG strains have different effects.

Methods

This was a parallel-group, open-label RCT conducted at the National Hospital in Guinea-Bissau. Healthy neonates were randomized 1:1 to BCG-Denmark (2851 randomized, 2840 analyzed) vs BCG-Russia (2845 randomized, 2837 analyzed). We hypothesized that BCG-Denmark would reduce morbidity (primary outcome) and mortality while inducing more BCG reactions and purified protein derivative (PPD) responses (secondary outcomes). Halfway through the trial, production of BCG-Denmark was halted, and the trial continued comparing BCG-Japan (3191 neonates randomized, 3184 analyzed) with BCG-Russia (3170 randomized, 3160 analyzed). Mortality and morbidity data were collected by telephone, at home visits, and at the National Hospital and assessed in Cox models providing 6-week mortality rate ratios (MRRs) and hospitalization incidence rate ratios (IRRs).

Results

By age 6 weeks, there were 140 and 130 admissions among neonates vaccinated with BCG-Denmark and BCG-Russia, respectively (IRR, 1.08 [95% confidence interval {CI}, .84–1.37]). For BCG-Japan, there were 185 admissions vs 161 admissions for BCG-Russia (IRR, 1.15 [95% CI, .93–1.43]). The 6-week mortality did not differ: BCG-Denmark/BCG-Russia (MRR, 1.15 [95% CI, .74–1.80]); BCG-Japan/BCG-Russia (MRR, 0.71 [95% CI, .43–1.19]). BCG-Denmark and BCG-Japan induced more BCG scars and PPD reactions than BCG-Russia.

Conclusions

BCG strains did not affect morbidity. BCG-Denmark and BCG-Japan were more immunogenic than BCG-Russia by the measures traditionally viewed as surrogates for successful immunization. The implications of strain differences for tuberculosis protection and overall health warrant further study.

Clinical Trials Registration

NCT02447536.

Evolution of the Bacillus Calmette-Guerin Scar and Its Association with Birth and Pregnancy Characteristics in a Prospective Cohort of Infants in Iquitos, Peru

BACKGROUND

Bacillus Calmette-Guerin (BCG) scar formation is considered a visual marker of vaccination and cell-mediated immune response. This study characterized the association between pregnancy and birth characteristics with BCG scar formation.

STUDY DESIGN

Pregnant women were enrolled prospectively. Infants were followed up for the first 6 months of life, and the diameter of the BCG scar was recorded. Marginal models were fitted to assess the association of BCG scar diameter with pregnancy and birth characteristics using linear regressions with generalized estimating equations.

RESULTS

A total of 307 infants were enrolled, of whom 19.2% (59/307) were of low birth weight. Among those with known gestational age, 7.1% were preterm births (21/295). Overall, 98.7% (303/307) of infants developed a BCG scar. BCG scar trends in a tropical environment, such as the Amazon, differ from the trends evidenced in the capital of Peru. For every additional week of gestational age, the mean scar diameter increased by 0.1 mm (95% confidence interval [CI]: 0.02, 0.24; p = 0.017). Maternal illness during pregnancy impacted BCG scar size, as the infants of mothers who self-report fever had a smaller scar diameter (1 mm, 95% CI: 0.5, 1.8 mm; p = 0.001).

CONCLUSION

The immune reaction to the BCG vaccination is affected by gestational age at birth and systemic inflammatory episodes during pregnancy.

Does BCG Vaccination Protect Against Nontuberculous Mycobacterial Infection? A Systematic Review and Meta-Analysis

Background

The incidence of nontuberculous mycobacterial (NTM) infections is increasing worldwide, particularly NTM lymphadenitis and skin infections (Buruli ulcer). This review summarizes the evidence for the protective effectiveness of BCG vaccination against NTM disease.

Methods

A systematic search using PRISMA guidelines was done for controlled studies investigating the protective effectiveness of BCG vaccination against NTM disease in immunocompetent individuals. This revealed 10 studies, including almost 12 million participants.

Results

Three cohort studies in industrialized countries suggest that the incidence of NTM lymphadenitis is greatly reduced among BCG-vaccinated children compared with BCG-unvaccinated children, with a risk ratio (RR) of 0.04 (95% confidence interval [CI], .01-.21). In two randomized trials in low-income countries, BCG protected against Buruli ulcer for the first 12 months following vaccination (RR, 0.50 [95% CI, .37-.69]). Four case-control studies had conflicting results. One cohort study found that individuals with Buruli ulcer are less likely to develop osteomyelitis if they have a BCG scar (RR, 0.36 [95% CI, .22-.58]). No studies have compared different BCG vaccine strains or the effect of revaccination in this setting.

Conclusions

The protective effect of BCG vaccination against NTM should be taken into consideration when deciding on recommendations for discontinuation of universal BCG vaccination programs and in assessing new vaccines designed to replace BCG.

Two Randomized Trials of the Effect of the Russian Strain of Bacillus Calmette-Guérin Alone or With Oral Polio Vaccine on Neonatal Mortality in Infants Weighing <2000 g in India

BACKGROUND

In randomized trials in Guinea-Bissau, the Danish strain of Bacillus Calmette-Guérin (BCG) reduces neonatal mortality, primarily by reducing deaths from pneumonia and sepsis. Because World Health Organization-prequalified BCG-Denmark was not available in India, we conducted 2 randomized trials to test whether BCG-Russia alone or with oral polio vaccine (OPV) has similar effects to BCG-Denmark.

METHODS

We randomized neonates weighing <2000 g to a control group that was not vaccinated before 28 days of age or to receive either BCG-Russia alone (first trial) or BCG-Russia with OPV (second trial) soon after birth. We performed intention-to-treat analysis using Cox hazards models with age as the underlying time and adjusted for weight, sex and inborn versus outborn status.

RESULTS

Administration of BCG-Russia alone had no effect on neonatal mortality (to 28 days of age): 15.6% of 1537 infants died in the BCG-Russia group and 16.1% of 1535 died in the control group; the adjusted hazard ratio was 0.95 [95% confidence interval (CI): 0.80-1.13]. Administration of BCG-Russia with OPV also had no effect on neonatal mortality: 18.0% of 1103 infants died in the BCG-OPV group and 17.6% of 1104 died in the control group; the adjusted hazard ratio was 1.01 (95% CI: 0.83-1.23). The adjusted hazard ratio for the 2 trials combined was 0.98 (95% CI: 0.85-1.11).

CONCLUSIONS

BCG-Russia with or without OPV had no effect on neonatal mortality. It is important to determine which strains of BCG have the greatest specific effects (on tuberculosis) and nonspecific effects (on infections other than tuberculosis) in high-mortality regions.

Safety and Immunogenicity of Early Bacillus Calmette-Guérin Vaccination in Infants Who Are Preterm and/or Have Low Birth Weights: A Systematic Review and Meta-analysis

IMPORTANCE

Bacillus Calmette-Guérin (BCG) vaccination is commonly delayed in infants who are preterm and have low birth weights (LBW) despite the association of early vaccination with better vaccination coverage and potentially nonspecific benefits for survival.

OBJECTIVE

To determine the safety, immunogenicity, and protective efficacy against tuberculosis (TB) of BCG vaccination given at or before 7 days after birth vs vaccination more than 7 days after birth among infants who are preterm and/or had LBW.

DATA SOURCES

Searches of Medline, Embase, and Global Health databases were conducted from inception until August 8, 2017.

STUDY SELECTION

Clinical trials, cohort studies, and case-control studies that included infants who were preterm and/or had LBW and reported safety, mortality, immunogenicity, proxies of vaccine take, and/or efficacy against TB.

DATA EXTRACTION AND SYNTHESIS

Two authors independently extracted data and assessed the quality of the studies. Data extracted included demographics, covariates, sources of bias, and effect estimates. Meta-analysis was performed using a random-effects model.

MAIN OUTCOMES AND MEASURES

Safety, mortality, immunogenicity, or other proxies of vaccine take, such as tuberculin skin test (TST) conversion and efficacy against tuberculosis.

RESULTS

Forty studies were included in a qualitative synthesis; infants who were preterm (born at 26-37 weeks' gestational age) and/or had LBW (0.69-2.5 kg at birth) were included. The BCG vaccine was administered at or before 7 days to 10 568 clinically stable infants who were preterm and/or had LBW; vaccination was administered to 4310 infants at varying times between 8 days and 12 months after birth. Twenty-one studies reporting safety found no cases of BCG-associated death or systemic disease in 8243 infants. Four studies reported no increase in all-cause mortality for infants who had LBW and who received early BCG vaccination compared with infants who had LBW with later vaccination or BCG-vaccinated infants of normal birth weight. Four studies reported lymphadenitis incidence; combined, these reported 0% to 2.9% incidence of vaccination within 7 days and 0% to 4.2% of vaccination after 7 days. Meta-analysis of 7 studies revealed no differences between early and delayed BCG vaccination for scar formation (n = 515; relative risk [RR], 1.01 [95% CI, 0.95-1.07]) or TST conversion (n = 397; RR, 0.97 [95% CI, 0.84-1.13]). Published data were insufficient to assess immunogenicity or protective efficacy against TB disease.

CONCLUSIONS AND RELEVANCE

Early BCG vaccination in healthy infants who are preterm and/or had LBW has a similar safety profile, reactogenicity, and TST conversion rate as delayed vaccination. Based on current evidence, early BCG vaccination in stable infants who are preterm and/or have LBW to optimize uptake is warranted.

An Overview of Coverage of BCG Vaccination and Its Determinants Based on Data from the Coverage Survey in Zhejiang Province

To assess the Bacille Calmette-Guérin (BCG) vaccination coverage in Zhejiang province and to investigate predictors of the BCG vaccination, we used data from the 2017 Zhejiang provincial coverage survey. Demographic and immunization data on the selected children, their mothers, and their families were also collected by using a pre-tested questionnaire. BCG scars were verified among children who were available at the moment of survey. Coverage of BCG and other expanded program on immunization (EPI) vaccines scheduled before the first year of life was calculated. BCG coverage through the scar assessment and timeliness of BCG were also presented. Multivariate analyses of the predictors associated with the BCG vaccination and its timeliness were conducted separately. In total, 1393 children agreed to participate in the survey and presented the immunization cards. Of them, the coverage of BCG was 92.0% and 88.3% received the BCG within the first 28 days after birth. Besides this, 1282 out of the 1393 children were screened for the BCG scars and 97.1% of them had developed the scars. The multivariable logistic regression analyses indicated that hospital delivery, higher maternal education, a mother with no job, and a resident child were positively associated with the higher BCG vaccination coverage and its timely administrations. BCG coverage was optimal and it was administered in a timely manner. The majority of children vaccinated with BCG developed scars. Tailored interventions should be more greatly focused on and targeted to children with the risk factors identified in this study.

BCG vaccination in southern rural Mozambique: an overview of coverage and its determinants based on data from the demographic and health surveillance system in the district of Manhiça

Background

Over the past four decades, the World Health Organization established the Expanded Programme on Immunization (EPI) to foster universal access to all relevant vaccines for all children at risk. The success of this program has been undeniable, but requires periodic monitoring to ensure that coverage rates remain high. The aim of this study was to measure the BCG vaccination coverage in Manhiça district, a high TB burden rural area of Southern Mozambique and to investigate factors that may be associated with BCG vaccination.

Methods

We used data from the Health and Demographic Surveillance System (HDSS) run by the Manhiça Health Research Centre (CISM) in the district of Manhiça. A questionnaire was added in the annual HDSS round visits to retrospectively collect the vaccination history of children under the age of 3 years. Vaccinations are registered in the National Health Cards which are universally distributed at birth. This information was collected for children born from 2011 to 2014. Data on whether a child was vaccinated for BCG were collected from these National Health Cards and/or BCG scar assessment.

Results

A total of 10,875 number of children were eligible for the study and 7903 presented the health card. BCG coverage was 97.4% for children holding a health card. A BCG-compatible scar was observed in 99.0% of all children and in 99.6% of children with recorded BCG in the card. A total of 93.4% of children had been vaccinated with BCG within their first 28 days of life. None of the factors analysed were found to be associated with lack of BCG vaccination except for living in the municipality of Maluana compared to living in the municipality of Manhiça; (OR = 1.89, 95% CI: 1.18-3.00). Coverage for other EPI vaccines during the first year of life was similarly high, but decreased for subsequent doses.

Conclusions

BCG coverage is high and timely administered. Almost all vaccinated infants develop scar, which is a useful proxy for monitoring BCG vaccine implementation.

Electronic supplementary material

The online version of this article (10.1186/s12887-018-1003-4) contains supplementary material, which is available to authorized users.

Determinants of BCG scarification among children in rural Guinea-Bissau: A prospective cohort study

Background: Bacillus Calmette-Guérin (BCG) vaccination may have beneficial non-specific effects on child survival, the effects being stronger for children developing a scar. In a prospective cohort study, we examined determinants for not developing a BCG scar within 6 months of vaccination.

Methods: Bandim Health Project (BHP) runs a Health and Demographic Surveillance System site in rural Guinea-Bissau. BHP provides BCG at monthly visits. We studied determinants for not developing a BCG scar using binomial regression models to obtain relative risks (RR).

Results: From May 2012 until October 2014, BHP nurses vaccinated 2415 infants with BCG. We assessed BCG scar between 6 and 12 months of age for 2156 (89%) of these children and 2115 (98%) had developed a scar. In comparison, among 785 children BCG vaccinated elsewhere, 622 (79%) had a scar, the RR of not having a scar being 10.91 (7.52-15.85) compared with children vaccinated by BHP.

Among children vaccinated by BHP, those receiving the Russian BCG strain were more likely not to develop a scar (RR = 2.98 (1.52–5.81)) compared with children receiving Danish BCG strain. Children with no post-injection wheal or a wheal <3 mm were more likely to not develop a scar (RR = 9.05 (3.69–22.20) and RR = 4.74 (1.96–11.45), respectively). Nutritional status and socioeconomic status were not associated with scarification.

Conclusion: Vaccination technique and vaccine strain were associated with BCG scar development while nutritional status and socioeconomic status were not. Scarring rate may therefore be a better indicator of vaccination programme performance than coverage.

The Effect of Smallpox and Bacillus Calmette-Guérin Vaccination on the Risk of Human Immunodeficiency Virus-1 Infection in Guinea-Bissau and Denmark

Background

The live smallpox and Bacillus Calmette-Guérin (BCG) vaccinations have been associated with better adult survival in both Guinea-Bissau and Denmark. In Guinea-Bissau, human immunodeficiency virus (HIV)-1 became an important cause of death after smallpox vaccination was phased out globally in 1980. We hypothesised that smallpox and BCG vaccinations were associated with a lower prevalence of HIV-1 infection, and we tested this hypothesis in both Guinea-Bissau and Denmark.

Methods

We conducted 2 studies: (1) a cross-sectional study of HIV infection and vaccination scars in Guinea-Bissau including 1751 individuals and (2) a case-base study with a background population of 46239 individuals in Denmark. In Guinea-Bissau, HIV-1 transmission was almost exclusively sexually transmitted. In Denmark, we excluded intravenous drug users. Data were analyzed using logistic regression.

Results

Bacillus Calmette-Guérin and/or smallpox vaccination compared with neither of these vaccines was associated with an adjusted odds ratio (aOR) for HIV-1 of 0.62 (95% confidence interval [CI], 0.36–1.07) in Guinea-Bissau and 0.70 (95% CI, 0.43–1.15) in Denmark. We combined the results from both settings in a meta-analysis (aOR = 0.66; 95% CI, 0.46–0.96). Data from Guinea-Bissau indicated a stronger effect of multiple smallpox vaccination scars (aOR = 0.27; 95% CI, 0.10–0.75) as follows: women, aOR = 0.18 (95% CI, 0.05–0.64); men, aOR = 0.52 (95% CI, 0.12–2.33); sex-differential effect, P = .29.

Conclusions

The studies from Guinea-Bissau and Denmark, 2 very different settings, both suggest that the BCG and smallpox vaccines could be associated with a decreased risk of sexually transmitted HIV-1. It might be informative to pursue this observation and explore possible protective mechanisms as part of the search for an HIV-1 vaccine.