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Global Health Research and Policy Nov 2022COVID-19 vaccination has been advocated as the most effective way to curb the pandemic. But with its inequitable distribution and slow rollout, especially in low- to... (Review)
Review
BACKGROUND
COVID-19 vaccination has been advocated as the most effective way to curb the pandemic. But with its inequitable distribution and slow rollout, especially in low- to middle- income countries, it will still take a long time before herd immunity is achieved. Alternative measures must therefore be explored to bolster current COVID-19 vaccination efforts. In particular, the Bacille Calmette-Guerin vaccine has been studied extensively as to its proposed conferment of non-specific immunity against different infections, including COVID-19. The aim of this study, therefore, is to evaluate the current evidence on the effectiveness of national BCG vaccination policies in reducing infection and mortality of COVID-19.
METHODS
A systematic review was conducted between April to August 2021 following the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA-P) guidelines. Literature was retrieved from PubMed, Cochrane, HERDIN, Web of Science, EBSCO, and Western Pacific Region Index Medicus (WPRIM). Studies conducted from January 2020 to August 2021 that fell within Level 1A to 2C of the Oxford Center for Evidence-Based Medicine were included in the review. Quality assessment was performed using the appropriate Joanna Briggs Institute critical appraisal tool and a quality assessment checklist for ecological studies adapted from Betran et al. RESULTS: A total of 13 studies were included in this review. Nine studies reported significant association between BCG vaccination policies and COVID-19 outcomes, even when controlling for confounding variables. In addition, among other mandated vaccines, such as pneumococcal, influenza, diphtheria-tetanus-pertussis, and measles, only BCG vaccination showed significant association with decreased COVID-19 adverse outcomes. However, other factors also showed positive association with COVID-19 outcomes, particularly markers of high economic status of countries, higher median age, and greater population densities.
CONCLUSION
The lower incidence and mortality of COVID-19 in countries with mandated BCG vaccination may not solely be attributable to BCG vaccination policies, but there is still some evidence that demonstrates a possible protective effect. Clinical trials must be continued before recommendations of BCG vaccinations are to be used as an alternative or booster vaccine against COVID-19.
Topics: Humans; BCG Vaccine; COVID-19; COVID-19 Vaccines; Policy; Vaccination
PubMed: 36336688
DOI: 10.1186/s41256-022-00275-x -
Journal of Global Health Oct 2022The integrated Global Action Plan for Prevention and Control of Pneumonia and Diarrhoea (GAPPD) has the goal of ending preventable childhood deaths from pneumonia and...
BACKGROUND
The integrated Global Action Plan for Prevention and Control of Pneumonia and Diarrhoea (GAPPD) has the goal of ending preventable childhood deaths from pneumonia and diarrhoea by 2025 with targets and indicators to monitor progress. The aim of this systematic review is to summarise how low-and-middle income countries (LMICs) reported pneumonia-specific GAPPD indicators at national and subnational levels and whether GAPPD targets have been achieved.
METHODS
We searched MEDLINE, Embase, PubMed and Global Health Databases, and the World Health Organization (WHO) website. Publications/reports between 2015 and 2020 reporting on two or more GAPPD-pneumonia indicators from LMICs were included. Data prior to 2015 were included if available in the same report series. Quality of publications was assessed with the Quality Assessment Tool for Quantitative Studies. A narrative synthesis of the literature was performed to describe which countries and WHO regions were reporting on GAPPD indicators and progress in GAPPD coverage targets.
RESULTS
Our search identified 17 publications/reports meeting inclusion criteria, with six from peer-reviewed publications. Data were available from 139 LMICs between 2010 and 2020, predominantly from Africa. Immunisation coverage rates were the indicators most commonly reported, followed by exclusive breastfeeding rates and pneumonia case management. Most GAPPD indicators were reported at the national level with minimal reporting at the subnational level. Immunisation coverage (Haemophilus influenzae, measles, diphtheria-tetanus-pertussis vaccines) in the WHO Europe, Americas and South-East Asia regions were meeting 90% coverage targets, while pneumococcal conjugate vaccine coverage lagged globally. The remaining GAPPD indicators (breastfeeding, pneumonia case management, antiretroviral prophylaxis, household air pollution) were not meeting GAPPD targets in LMICs. There was a strong negative correlation between pneumonia specific GAPPD coverage rates and under-five mortality (Pearson correlation coefficient range = -0.74, -0.79).
CONCLUSION
There is still substantial progress to be made in LMICs to achieve the 2025 GAPPD targets. Current GAPPD indicators along with country reporting mechanisms should be reviewed with consideration of adding undernutrition and access to oxygen therapy as important indicators which impact pneumonia outcomes. Further research on GAPPD indicators over longer time periods and at subnational levels can help identify high-risk populations for targeted pneumonia interventions.
Topics: Child; Humans; Developing Countries; Vaccines, Conjugate; Pneumonia; Diarrhea; Oxygen
PubMed: 36282893
DOI: 10.7189/jogh.12.10006 -
Human Vaccines & Immunotherapeutics Nov 2022Although the burden of diphtheria has declined greatly since the introduction of vaccines, sporadic outbreaks continue to be reported. WHO recommends booster doses after...
Waning rate of immunity and duration of protective immunity against diphtheria toxoid as a function of age and number of doses: Systematic review and quantitative data analysis.
Although the burden of diphtheria has declined greatly since the introduction of vaccines, sporadic outbreaks continue to be reported. WHO recommends booster doses after a primary series, but questions remain about the optimal interval between these doses. We conducted a systematic review and quantitative data analysis to quantify the duration of protective immunity after different numbers of doses. Fifteen cross-sectional seroprevalence studies provided data on geometric mean concentration (GMC). Single-year age-stratified GMCs were analyzed using a mixed-effect linear regression model with a random intercept incorporating the between-country variability. GMC was estimated to decline to 0.1 IU/ml in 2.5 years (95% CI: 0.9-4.0), 10.3 years (95% CI: 7.1-13.6), and 25.1 years (95% CI: 7.6-42.6) after receiving three, four and five doses, respectively. The results drawn from cross-sectional data collected in countries with different epidemiologies, vaccines, and schedules had several limitations. However, these analyses contribute to the discussion of optimal timing between booster doses of diphtheria toxoid-containing vaccine.
Topics: Humans; Diphtheria-Tetanus-Pertussis Vaccine; Seroepidemiologic Studies; Cross-Sectional Studies; Diphtheria Toxoid; Diphtheria; Data Analysis; Antibodies, Bacterial; Immunization, Secondary
PubMed: 35862651
DOI: 10.1080/21645515.2022.2099700 -
Frontiers in Immunology 2022Common vaccinations may have impacts on dementia risk, but current evidence is inconsistent. We therefore investigated the association between vaccinations and dementia... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Common vaccinations may have impacts on dementia risk, but current evidence is inconsistent. We therefore investigated the association between vaccinations and dementia risk by systematic review and meta-analysis approach.
METHODS
We conducted an extensive search of PubMed, Embase, Cochrane Library, and Web of Science to identify studies that compared the risk of dementia in vaccinated versus unvaccinated populations. The adjusted hazard ratio (HR) and corresponding 95% confidence intervals (CIs) were pooled as measures.
RESULTS
Of the 9124 records initially retrieved, 17 studies with 1857134 participants were included in our analysis. The overall pooled results showed that vaccinations were associated with a 35% lower dementia risk (HR=0.65, 95% CI: 0.60-0.71, < 0.001; 91.8%, <0.001). All types of vaccination were associated with a trend toward reduced dementia risk, with rabies (HR=0.43), tetanus & diphtheria & pertussis (Tdap) (HR=0.69), herpes zoster (HR=0.69), influenza (HR=0.74), hepatitis A (HR=0.78), typhoid (HR=0.80), and hepatitis B (HR=0.82) vaccinations being significant. Individuals with more full vaccination types and more annual influenza vaccinations were less likely to develop dementia. Gender and age had no effect on this association.
CONCLUSION
Routine adult vaccinations are associated with a significant reduction in dementia risk and may be an effective strategy for dementia prevention. Further research is needed to elucidate the causal effects of this association and the underlying mechanisms.
Topics: Adult; Dementia; Diphtheria; Humans; Influenza, Human; Protective Factors; Vaccination
PubMed: 35592323
DOI: 10.3389/fimmu.2022.872542 -
The Lancet. Infectious Diseases Sep 2022Understanding why some migrants in Europe are at risk of underimmunisation and show lower vaccination uptake for routine and COVID-19 vaccines is critical if we are to... (Review)
Review
Understanding why some migrants in Europe are at risk of underimmunisation and show lower vaccination uptake for routine and COVID-19 vaccines is critical if we are to address vaccination inequities and meet the goals of WHO's new Immunisation Agenda 2030. We did a systematic review (PROSPERO: CRD42020219214) exploring barriers and facilitators of vaccine uptake (categorised using the 5As taxonomy: access, awareness, affordability, acceptance, activation) and sociodemographic determinants of undervaccination among migrants in the EU and European Economic Area, the UK, and Switzerland. We searched MEDLINE, CINAHL, and PsycINFO from 2000 to 2021 for primary research, with no restrictions on language. 5259 data sources were screened, with 67 studies included from 16 countries, representing 366 529 migrants. We identified multiple access barriers-including language, literacy, and communication barriers, practical and legal barriers to accessing and delivering vaccination services, and service barriers such as lack of specific guidelines and knowledge of health-care professionals-for key vaccines including measles-mumps-rubella, diphtheria-pertussis-tetanus, human papillomavirus, influenza, polio, and COVID-19 vaccines. Acceptance barriers were mostly reported in eastern European and Muslim migrants for human papillomavirus, measles, and influenza vaccines. We identified 23 significant determinants of undervaccination in migrants (p<0·05), including African origin, recent migration, and being a refugee or asylum seeker. We did not identify a strong overall association with gender or age. Tailored vaccination messaging, community outreach, and behavioural nudges facilitated uptake. Migrants' barriers to accessing health care are already well documented, and this Review confirms their role in limiting vaccine uptake. These findings hold immediate relevance to strengthening vaccination programmes in high-income countries, including for COVID-19, and suggest that tailored, culturally sensitive, and evidence-informed strategies, unambiguous public health messaging, and health system strengthening are needed to address access and acceptance barriers to vaccination in migrants and create opportunities and pathways for offering catch-up vaccinations to migrants.
Topics: COVID-19; COVID-19 Vaccines; Europe; Health Services Accessibility; Humans; Measles; Transients and Migrants; Vaccination; Vaccines
PubMed: 35429463
DOI: 10.1016/S1473-3099(22)00066-4 -
Vaccines Mar 2022Background: Vaccination is considered the most effective and economical measure for controlling infectious diseases. Although combination vaccines are widely used... (Review)
Review
Background: Vaccination is considered the most effective and economical measure for controlling infectious diseases. Although combination vaccines are widely used worldwide, whether any of the combination vaccines is superior to each separate vaccine has yet to be established. This systematic review and meta-analysis aimed to summarize the available evidence on the effectiveness and safety of combination vaccines in children. Methods: A systematic search was conducted from database inception to August 20, 2021, in MEDLINE, Embase, Cochrane, and Scopus. Published randomized clinical trials (RCTs) and open-label trials of immunogenicity and safety of combined vaccines were selected. The results of the studies were quantitatively synthesized. Results: Overall, 25 articles met the inclusion criteria and were included in the meta-analysis. The results indicated that the combined diptheria−tetanus−acellular pertussis (DTaP)−hepatitis B virus (HBV)−Haemophilus influenzae type B (Hib) vaccine group had lower levels of anti-tetanus antibodies than the combined DTaP−HBV and separate Hib vaccinations group (SMD = −0.23; 95% CI: −0.42, −0.05; p = 0.013). Meanwhile, the combined DTaP−HBV−inactivated polio virus (IPV)−Hib vaccine group had higher levels of anti-pertussis (PT) and anti-filamentous hemagglutinin (FHA) antibodies than the combined DTaP−IPV−Hib and separate HBV vaccinations group (anti-PT: SMD = 0.60; 95% CI: 0.45, 0.75; p < 0.0001; anti-FHA: SMD = 0.40; 95% CI: 0.01, 0.78; p = 0.042). The levels of anti-pertactin (PRN) antibodies were lower in the combined DTaP−IPV−Hib vaccine group than in the combined DTaP−IPV and separate Hib vaccinations group (SMD = −0.13; 95% CI: −0.27, −0.00; p = 0.047). The individuals injected with the DTaP−HBV−IPV−Hib vaccine had a lower risk of pain and swelling than those injected with the combined DTaP−HBV−IPV and separate Hib vaccines (pain: RR = 0.79; 95% CI: 0.69, 0.91; p = 0.001; swelling: RR = 0.87; 95% CI: 0.78, 0.98; p = 0.020). However, the group that received the DTaP−HBV−IPV−Hib vaccine had a higher risk of fever than the group that received DTaP−HBV−IPV and separate Hib vaccinations (RR = 1.13; 95% CI: 1.02, 1.26; p = 0.021). Conclusions: This meta-analysis suggests that the combined vaccines (DTaP−IPV−Hib, DTaP−HBV−Hib, DTaP−HBV−IPV−Hib) are safe, well-tolerated, and provide immunogenic alternatives to separate vaccines in children. The combined DTaP−HBV−IPV−Hib vaccine showed a higher incidence of fever, which was lower than the cumulative incidence of fever induced by all vaccines. Future studies should evaluate the cost-effectiveness of using combined vaccines and compare the potency of different formulations to improve routine local or national childhood immunization programs.
PubMed: 35335107
DOI: 10.3390/vaccines10030472 -
The Cochrane Database of Systematic... Sep 2021Atopic diseases are the most common chronic conditions of childhood. The apparent rise in food anaphylaxis in young children over the past three decades is of particular... (Review)
Review
BACKGROUND
Atopic diseases are the most common chronic conditions of childhood. The apparent rise in food anaphylaxis in young children over the past three decades is of particular concern, owing to the lack of proven prevention strategies other than the timely introduction of peanut and egg. Due to reported in vitro differences in the immune response of young infants primed with whole-cell pertussis (wP) versus acellular pertussis (aP) vaccine, we systematically appraised and synthesised evidence on the safety and the potential allergy preventive benefits of wP, to inform recommendation for future practice and research.
OBJECTIVES
To assess the efficacy and safety of wP vaccinations in comparison to aP vaccinations in early infancy for the prevention of atopic diseases in children.
SEARCH METHODS
We searched the Cochrane Central Register of Controlled Trials, Ovid MEDLINE, Embase, and grey literature. The date of the search was 7 September 2020.
SELECTION CRITERIA
We included randomised controlled trials (RCTs) and non-randomised studies of interventions (NRSIs) that reported the occurrence of atopic diseases, and RCTs only to assess safety outcomes. To be included studies had to have at least six months follow-up, and involve children under 18 years old, who received a first dose of either wP (experimental intervention) or aP (comparator) before six months of age.
DATA COLLECTION AND ANALYSIS
Two review authors independently screened studies for eligibility, extracted the data, and assessed risk of bias using standard Cochrane methods. We assessed the certainty of the evidence using GRADE. Our primary outcomes were diagnosis of IgE-mediated food allergy and all-cause serious adverse events (SAEs). Secondary outcomes included: diagnosis of not vaccine-associated anaphylaxis or urticaria, diagnosis of asthma, diagnosis of allergic rhinitis, diagnosis of atopic dermatitis and diagnosis of encephalopathy. Due to paucity of RCTs reporting on the atopic outcomes of interest, we assessed a broader outcome domain (cumulative incidence of atopic disease) as specified in our protocol. We summarised effect estimates as risk ratios (RR) and 95% confidence intervals (CI). Where appropriate, we pooled safety data in meta-analyses using fixed-effect Mantel-Haenszel methods, without zero-cell corrections for dichotomous outcomes.
MAIN RESULTS
We identified four eligible studies reporting on atopic outcomes, representing 7333 children. Based on a single trial, there was uncertain evidence on whether wP vaccines affected the risk of overall atopic disease (RR 0.85, 95% CI 0.62 to 1.17) or asthma only (RR 1.04, 95% CI 0.59 to 1.82; 497 children) by 2.5 years old.Three NRSIs were judged to be at serious or critical risk of bias due to confounding, missing data, or both, and were ineligible for inclusion in a narrative synthesis. We identified 21 eligible studies (137,281 children) that reported the safety outcomes of interest. We judged seven studies to be at high risk of bias and those remaining, at unclear risk. The pooled RR was 0.94 for all-cause SAEs (95% CI 0.78 to 1.15; I = 0%; 15 studies, 38,072 children). For every 1000 children primed with a first dose of wP, 11 had an SAE. The corresponding risk with aP was 12 children (95% CI 9 to 13). The 95% CI around the risk difference ranged from three fewer to two more events per 1000 children, and the certainty of the evidence was judged as moderate (downgraded one level for imprecision). No diagnoses of encephalopathy following vaccination were reported (95% CI around the risk difference - 5 to 12 per 100,000 children; seven primary series studies; 115,271 children). The certainty of the evidence was judged as low, since this is a serious condition, and we could not exclude a clinically meaningful difference.
AUTHORS' CONCLUSIONS
There is very low-certainty evidence that a first dose of wP given early in infancy, compared to a first dose of aP, affects the risk of atopic diseases in children. The incidence of all-cause SAEs in wP and aP vaccinees was low, and no cases of encephalopathy were reported. The certainty of the evidence was judged as moderate for all-cause SAEs, and low for encephalopathy. Future studies should use sensitive and specific endpoints of clinical relevance, and should be conducted in settings with high prevalence of IgE-mediated food allergy. Safety endpoints should prioritise common vaccine reactions, parental acceptability, SAEs and their potential relatedness to the dose administered.
Topics: Adolescent; Bias; Child; Child, Preschool; Eczema; Humans; Hypersensitivity, Immediate; Pertussis Vaccine; Whooping Cough
PubMed: 34693993
DOI: 10.1002/14651858.CD013682.pub2 -
Allergy, Asthma & Immunology Research Sep 2021Our prior work and the work of others have demonstrated that asthma increases the risk of a broad range of both respiratory (, pneumonia and pertussis) and... (Review)
Review
Risk, Mechanisms and Implications of Asthma-Associated Infectious and Inflammatory Multimorbidities (AIMs) among Individuals With Asthma: a Systematic Review and a Case Study.
Our prior work and the work of others have demonstrated that asthma increases the risk of a broad range of both respiratory (, pneumonia and pertussis) and non-respiratory (, zoster and appendicitis) infectious diseases as well as inflammatory diseases (, celiac disease and myocardial infarction [MI]), suggesting the systemic disease nature of asthma and its impact beyond the airways. We call these conditions asthma-associated infectious and inflammatory multimorbidities (AIMs). At present, little is known about why some people with asthma are at high-risk of AIMs, and others are not, to the extent to which controlling asthma reduces the risk of AIMs and which specific therapies mitigate the risk of AIMs. These questions represent a significant knowledge gap in asthma research and unmet needs in asthma care, because there are no guidelines addressing the identification and management of AIMs. This is a systematic review on the association of asthma with the risk of AIMs and a case study to highlight that 1) AIMs are relatively under-recognized conditions, but pose major health threats to people with asthma; 2) AIMs provide insights into immunological and clinical features of asthma as a systemic inflammatory disease beyond a solely chronic airway disease; and 3) it is time to recognize AIMs as a distinctive asthma phenotype in order to advance asthma research and improve asthma care. An improved understanding of AIMs and their underlying mechanisms will bring valuable and new perspectives improving the practice, research, and public health related to asthma.
PubMed: 34486256
DOI: 10.4168/aair.2021.13.5.697 -
Infectious Diseases and Therapy Dec 2021Pertussis (whooping cough) epidemics persist globally despite high vaccine coverage among infants and young children. The resurgence of pertussis in high-income... (Review)
Review
Pertussis (whooping cough) epidemics persist globally despite high vaccine coverage among infants and young children. The resurgence of pertussis in high-income countries is partly due to waning vaccine immunity, resulting in a pool of unprotected adolescents and adults. However, pertussis is generally less severe in adolescents and adults, and this difference in presentation means it can often be unrecognised by healthcare professionals, meaning that it is largely under-diagnosed in older populations. A systematic search of MEDLINE, EMBASE and BIOSIS was undertaken to identify studies published between 1 January 1990 and 17 June 2019, with information on pertussis epidemiology and mortality in school-aged children, adolescents and adults in Europe. A formal statistical comparison (e.g. using meta-analyses) was not possible because of the mix of methodologies reported. There were 69 epidemiological studies and 19 mortality studies identified for review. Over the past decade, the reported incidence of notified pertussis cases varied widely between European countries, which is likely associated with differences in surveillance systems, diagnostic techniques and reporting regulations. However, several studies show that pertussis is circulating among adolescents and adults in Europe, and although pertussis-related morbidity and mortality are highest in infants, there is evidence that adults aged > 50 years are at increased risk. For example, in a hospital-based surveillance study in Portugal, between 2000 and 2015, 94% of hospitalised pertussis cases were infants aged < 1 year, with a case fatality rate (CFR) of 0.8%; however, among hospitalised adult cases of pertussis, the CFRs were 11.5% (aged 18-64 years) and 17.4% (aged > 65 years). Very few European countries currently include pertussis boosters for adults in the national immunisation strategy. In addition to increasing pertussis vaccination coverage in adolescents and adults, mitigation strategies in European countries should include improved diagnosis and treatment in these populations.
PubMed: 34435338
DOI: 10.1007/s40121-021-00520-9 -
Frontiers in Immunology 2021Immunization with tetanus-diphtheria-acellular pertussis (Tdap) vaccine in pregnancy is increasingly recommended. We determined the effect of Tdap immunization in... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Immunization with tetanus-diphtheria-acellular pertussis (Tdap) vaccine in pregnancy is increasingly recommended. We determined the effect of Tdap immunization in pregnancy on infants' vaccine responses.
METHODS
Individual-participant data meta-analysis of ten studies (n=1884) investigating infants' antibody response to routine immunizations following Tdap immunization in pregnancy was performed. Geometric mean ratios (GMRs) of antigen-specific immunoglobulin G (IgG) levels were calculated using mixed-effects models. Seroprotection rates were compared using chi-squared tests.
RESULTS
Infants of Tdap-immunized women had significantly lower IgG against pertussis toxin (GMR 0.65; 95%CI 0.57-0.74), filamentous haemagglutinin (FHA) (0.68; 0.53-0.87), pertactin (0.65; 0.58-0.72) and fimbria 2/3 (FIM2/3) (0.41; 0.32-0.52) after primary immunization, compared with infants of unimmunized women. These lower levels persisted after booster immunization for FHA (0.72; 0.61-0.84) and FIM2/3 (0.53; 0.29-0.96). After primary immunization, infants of Tdap-immunized women had lower seroprotection rates against diphtheria (90% [843/973] 98% [566/579]; p<0.001) and invasive pneumococcal disease (IPD) caused by 5 (SPN) serotypes (SPN5, SPN6B, SPN9V, SPN19A, SPN23F), and higher seroprotection rates against type b (short-term and long-term seroprotection rates, 86%[471/547] 76%[188/247] and 62%[337/547] 49%(121/247), respectively, all p=0.001). After booster immunization, seroprotection rates against diphtheria and tetanus were 99% (286/288) and (618/619) in infants of Tdap-immunized women, respectively.
CONCLUSIONS
Infants of Tdap-immunized women in pregnancy had lower IgG levels against pertussis, diphtheria and some SPN serotypes after their immunization compared with infants of unimmunized women. Enhanced surveillance of pertussis, diphtheria and IPD in infants is needed to determine the clinical significance of these findings.
SYSTEMATIC REVIEW REGISTRATION
CRD42017079171.
Topics: Antibodies, Bacterial; Diphtheria; Diphtheria-Tetanus-acellular Pertussis Vaccines; Female; Humans; Immunoglobulin G; Infant; Pregnancy; Tetanus; Vaccination; Whooping Cough
PubMed: 34305922
DOI: 10.3389/fimmu.2021.689394