Public health partnerships with faith-based organizations to support vaccination uptake among minoritized communities: A scoping review.

Faith-based vaccine initiatives are of growing interest to public health agencies who are looking to increase vaccine confidence among ethnoracially minoritized populations. Despite evidence that support faith-based organizations' (FBOs) partnerships with public health agencies (PHAs) to increase vaccine confidence, reviews on the scope and efforts to ensure equitable vaccination delivery for ethnoracially minoritized populations are scarce. We aimed to understand how public health agencies collaborate with FBOs or faith communities to improve vaccine confidence among minoritized communities in high-, low- and middle- income countries. We conducted a scoping review by searching OVID MEDLINE, Cochrane Library, Cumulative Index to Nursing and Allied Health Literature (CINAHL), SCOPUS, and PROQUEST from 2011 to 2023. We included case studies, news reports, observational studies, experimental, and quasi-experimental studies and multimedia content that describes PHA-FBO partnerships that created vaccine initiatives for marginalized and minoritized communities. The data was extracted, summarized, and results were described narratively. We included 167 initiatives reported in 160 publications; 83.8% of the included articles were published between 2019 to 2023. The interventions carried out by PHA-FBO partnerships attempted to increase vaccine uptake using any or all the following methods. First, the initiatives provided digital and in-person platforms for interfaith learning and established training programs to empower faith leaders to become vaccine ambassadors. Second, the initiatives designed and disseminated education and awareness materials that aimed to be sensitive to religious and gender norms. Third, PHA-FBO partnered to apply equity and faith-based frameworks and provided wrap-around support to enable equitable vaccine access. Majority of the initiatives reported that PHA-FBO partnerships improved vaccine confidence and uptake (71.3%). About 22.2% of the initiatives reported quantitative outcomes post-intervention. PHA-FBO initiatives over the past decade increased vaccine uptake and acceptance among diverse ethnoracially minoritized populations. Reporting of faith-based initiatives are subject to publication bias and can be strengthened by examining more evaluation studies and establishment of key outcome indicators to critically appraise intervention outcomes.

Indirect impact of childhood 13-valent pneumococcal conjugate vaccine (PCV13) in Canadian older adults: a Canadian Immunization Research Network (CIRN) retrospective observational study.

BACKGROUND: 13-valent pneumococcal conjugate vaccine (PCV13) has been part of publicly funded childhood immunisation programmes in Ontario and British Columbia (BC) since 2010. We assessed the indirect impact of infant PCV13 programmes on invasive pneumococcal disease (IPD) and all-cause pneumonia hospitalisation in older adults (aged ≥65 years) using a retrospective observational study. METHODS: We extracted monthly IPD and all-cause pneumonia cases from laboratory and health administrative databases between January 2005 and December 2018. Using a quasi-experimental difference-in-differences design, we calculated the ratio of risk ratios (RRRs) using incidence rates of IPD or all-cause pneumonia cases before (pre-PCV13 period) and after (PCV13 period) 2010 with rates of fractures as controls. RESULTS: The rates of all IPD or PCV serotype-specific IPD for older adults in both Ontario and BC did not change in 8 years after childhood PCV13 programme implementation. All-cause pneumonia increased in Ontario (RRR 1.38, 95% CI 1.11 to 1.71) but remained unchanged in BC. CONCLUSIONS: Indirect community protection of older adults from hospitalisation with pneumococcal disease stalled despite maturation of childhood PCV13 vaccination programmes in two Canadian provinces.

The mental health impact of the COVID-19 pandemic on post-secondary students: A longitudinal study.

This prospective longitudinal study measured sex-specific changes in depression, anxiety, and stress scores using, validated Patient Health Questionnaire-9 (PHQ-9), Generalized Anxiety Disorder-7 (GAD-7), and the Perceived Stress Scale (PSS) in a cohort of 1445 post-secondary students (500 males, 945 females) assessed at three time points from December 2020 to January 2022. Participants were ascertained from a population of 15,585 students with in-person activities on campus at baseline and recruited from December 2020 to January 2021. We also assessed how sociodemographic characteristics influenced students' mental health outcomes. Inverse probability weighting was used to account for missing data and attrition. Linear mixed effects models were used to analyze the relationship between the mental health scores in each questionnaire, demographic and academic data, and public health stringency measured by the local stringency index. No change was observed in questionnaire scores over time for males and females, but the stringency index was significantly associated with increased stress. Being in a non-health-related-field or being white affected males and females differently for stress and anxiety, but not depression. Demographics tended to be more influential on females' mental health than males. In conclusion, mental health resource allocation in time of emerging pandemic could benefit from targeted interventions.

Increasing pneumococcal vaccine uptake in older adults: a scoping review of interventions in high-income countries.

BACKGROUND: There is low uptake of the pneumococcal vaccination in eligible older adults, even in high-income countries that offer routine and universal vaccination programs. OBJECTIVE: To systematically characterize interventions aimed at improving pneumococcal vaccine uptake in older adults. DESIGN: We conducted a scoping review following PRISMA-SCr guidelines of five interdisciplinary databases: Medline-Ovid, Embase, CINAHL, PsychInfo, and Cochrane Library. Databases were searched from January 2015 until April 2020. The interventions were summarized into three pillars according to the European Union Conceptional Framework for Action: information campaigns, prioritization of vaccination schemes, and primary care interventions. RESULTS: Our scoping review included 39 studies that summarized interventions related to pneumococcal vaccine uptake for older adults, encompassing 2,481,887 study participants (945 healthcare providers and 2,480,942 older adults) across seven countries. Examples of interventions that were associated with increased pneumococcal vaccination rate included periodic health examinations, reminders and decision-making tools built into electronic medical records, inpatient vaccination protocols, preventative health checklists, and multimodal educational interventions. When comparing the three pillars, prioiritization of vaccination schemes had the highest evidence for improved rates of vaccination (n = 14 studies), followed by primary care interventions (n = 8 studies), then information campaigns (n = 5 studies). CONCLUSION: Several promising interventions were associated with improved outcomes related to vaccine uptake, although controlled study designs are needed to determine which interventions are most effective.

Estimating population-based incidence of community-acquired pneumonia and acute otitis media in children and adults in Ontario and British Columbia using health administrative data, 2005-2018: a Canadian Immunisation Research Network (CIRN) study.

BACKGROUND: There is a paucity of data on the burden of the full spectrum of community-acquired pneumonia (CAP) and acute otitis media (AOM) from outpatient and inpatient settings across the age spectrum. METHODS: We conducted a population-based retrospective study in Ontario and British Columbia (BC), Canada, to estimate the incidence rate of CAP and AOM in children and adults over a 14-year period using health administrative databases. CAP and AOM cases were identified from outpatient physician consultation and hospitalisation data in both provinces, and from emergency department visit data in Ontario. RESULTS: During 2005-2018, Ontario had 3 607 124 CAP, 172 290 bacterial CAP, 7814 pneumococcal pneumonia, and 8 026 971 AOM cases. The incidence rate of CAP declined from 3077/100 000 in 2005 to 2604/100 000 in 2010 before increasing to 2843/100 000 in 2018; bacterial CAP incidence rate also declined from 178/100 000 in 2005 to 112/100 000 in 2010 before increasing to 149/100 000 in 2018. The incidence rate of AOM decreased from 4192/100 000 in 2005 to 3178/100 000 in 2018. BC had 970 455 CAP, 317 913 bacterial CAP, 35 287 pneumococcal pneumonia and 2 022 871 AOM cases. The incidence rate of CAP in BC decreased from 2214/100 000 in 2005 to 1964/100 000 in 2010 before increasing to 2176/100 000 in 2018; bacterial CAP incidence rate increased from 442/100 000 in 2005 to 981/100 000 in 2018. The incidence rate of AOM decreased from 3684/100 000 in 2005 to 2398/100 000 in 2018. The incidence rate of bacterial CAP increased with age in older adults (≥65 years) with the highest burden in the oldest cohort aged ≥85 years both before and after 13-valent pneumococcal conjugate vaccine (PCV13) programme in both provinces. Hospitalised pneumococcal pneumonia decreased slightly but non-hospitalised pneumococcal pneumonia increased in BC during PCV13 period. No consistent direct benefit of PCV13 on CAP was observed in the paediatric population. CONCLUSIONS: There is a substantial burden of CAP and AOM in Ontario and BC. Indirect benefits from childhood PCV vaccination and polysaccharide vaccination of older adults have not substantially decreased the burden of pneumococcal pneumonia in older adults.

National Burden Estimates of healthy life lost in India, 2017: an analysis using direct mortality data and indirect disability data.

BACKGROUND: Many countries, including India, seek locally constructed disease burden estimates comprising mortality and loss of health to aid priority setting for the prevention and treatment of diseases. We created the National Burden Estimates (NBE) to provide transparent and understandable disease burdens at the national and subnational levels, and to identify gaps in knowledge. METHODS: To calculate the NBE for India, we combined 2017 UN death totals with national and subnational mortality rates for 2010-17 and causes of death from 211 166 verbal autopsy interviews in the Indian Million Death Study for 2010-14. We calculated years of life lost (YLLs) and years lived with disability (YLDs) for 2017 using published YLD-YLL ratios from WHO Global Health Estimates. We grouped causes of death into 45 groups, including ill-defined deaths, and summed YLLs and YLDs to calculate disability-adjusted life-years (DALYs) for these causes in eight age groups covering rural and urban areas and 21 major states of India. FINDINGS: In 2017, there were about 9·7 million deaths and 486 million DALYs in India. About three quarters of deaths and DALYs occurred in rural areas. More than a third of national DALYs arose from communicable, maternal, perinatal, and nutritional disorders. DALY rates in rural areas were at least twice those of urban areas for perinatal and nutritional conditions, chronic respiratory diseases, diarrhoea, and fever of unknown origin. DALY rates for ischaemic heart disease were greater in urban areas. Injuries caused 11·4% of DALYs nationally. The top 15 conditions that accounted for the most DALYs were mostly those causing mortality (ischaemic heart disease, perinatal conditions, chronic respiratory diseases, diarrhoea, respiratory infections, cancer, stroke, road traffic accidents, tuberculosis, and liver and alcohol-related conditions), with disability mostly due to a few conditions (nutritional deficiencies, neuropsychiatric conditions, vision and other sensory loss, musculoskeletal disorders, and genitourinary diseases). Every condition that was common in one part of India was uncommon elsewhere, suggesting state-specific priorities for disease control. INTERPRETATION: The NBE method quantifies disease burden using transparent, intuitive, and reproducible methods. It provides a simple, locally operable tool to aid policy makers in priority setting in India and other low-income and middle-income countries. The NBE underlines the need for many more countries to collect nationally representative cause of death data, paired with focused surveys of disability. FUNDING: Ministry of Health and Family Welfare, Government of India.

Seasonal variation and etiologic inferences of childhood pneumonia and diarrhea mortality in India.

Control of pneumonia and diarrhea mortality in India requires understanding of their etiologies. We combined time series analysis of seasonality, climate region, and clinical syndromes from 243,000 verbal autopsies in the nationally representative Million Death Study. Pneumonia mortality at 1 month-14 years was greatest in January (Rate ratio (RR) 1.66, 99% CI 1.51-1.82; versus the April minimum). Higher RRs at 1-11 months suggested respiratory syncytial virus (RSV) etiology. India's humid subtropical region experienced a unique summer pneumonia mortality. Diarrhea mortality peaked in July (RR 1.66, 1.48-1.85) and January (RR 1.37, 1.23-1.48), while deaths with fever and bloody diarrhea (indicating enteroinvasive bacterial etiology) showed little seasonality. Combining mortality at ages 1-59 months with prevalence surveys, we estimate 40,600 pneumonia deaths from Streptococcus pneumoniae, 20,700 from RSV, 12,600 from influenza, and 7200 from Haemophilus influenzae type b and 24,700 diarrheal deaths from rotavirus occurred in 2015. Careful mortality studies can elucidate etiologies and inform vaccine introduction.

National, regional, and state-level all-cause and cause-specific under-5 mortality in India in 2000-15: a systematic analysis with implications for the Sustainable Development Goals.

BACKGROUND: India had the largest number of under-5 deaths of all countries in 2015, with substantial subnational disparities. We estimated national and subnational all-cause and cause-specific mortality among children younger than 5 years annually in 2000-15 in India to understand progress made and to consider implications for achieving the Sustainable Development Goal (SDG) child survival targets. METHODS: We used a multicause model to estimate cause-specific mortality proportions in neonates and children aged 1-59 months at the state level, with causes of death grouped into pneumonia, diarrhoea, meningitis, injury, measles, congenital abnormalities, preterm birth complications, intrapartum-related events, and other causes. AIDS and malaria were estimated separately. The model was based on verbal autopsy studies representing more than 100 000 neonatal deaths globally and 16 962 deaths among children aged 1-59 months at the subnational level in India. By applying these proportions to all-cause deaths by state, we estimated cause-specific numbers of deaths and mortality rates at the state, regional, and national levels. FINDINGS: In 2015, there were 25·121 million livebirths in India and 1·201 million under-5 deaths (under-5 mortality rate 47·81 per 1000 livebirths). 0·696 million (57·9%) of these deaths occurred in neonates. There were disparities in child mortality across states (from 9·7 deaths [Goa] to 73·1 deaths [Assam] per 1000 livebirths) and regions (from 29·7 deaths [the south] to 63·8 deaths [the northeast] per 1000 livebirths). Overall, the leading causes of under-5 deaths were preterm birth complications (0·330 million [95% uncertainty range 0·279-0·367]; 27·5% of under-5 deaths), pneumonia (0·191 million [0·168-0·219]; 15·9%), and intrapartum-related events (0·139 million [0·116-0·165]; 11·6%), with cause-of-death distributions varying across states and regions. In states with very high under-5 mortality, infectious-disease-related causes (pneumonia and diarrhoea) were among the three leading causes, whereas the three leading causes were all non-communicable in states with very low mortality. Most states had a slower decline in neonatal mortality than in mortality among children aged 1-59 months. Ten major states must accelerate progress to achieve the SDG under-5 mortality target, while 17 are not on track to meet the neonatal mortality target. INTERPRETATION: Efforts to reduce vaccine-preventable deaths and to reduce geographical disparities should continue to maintain progress achieved in 2000-15. Enhanced policies and programmes are needed to accelerate mortality reduction in high-burden states and among neonates to achieve the SDG child survival targets in India by 2030. FUNDING: Bill & Melinda Gates Foundation.

The impact of measles immunization campaigns in India using a nationally representative sample of 27,000 child deaths.

India comprises much of the persisting global childhood measles mortality. India implemented a mass second-dose measles immunization campaign in 2010. We used interrupted time series and multilevel regression to quantify the campaign's impact on measles mortality using the nationally representative Million Death Study (including 27,000 child deaths in 1.3 million households surveyed from 2005 to 2013). 1-59 month measles mortality rates fell more in the campaign states following launch (27%) versus non-campaign states (11%). Declines were steeper in girls than boys and were specific to measles deaths. Measles mortality risk was lower for children living in a campaign district (OR 0.6, 99% CI 0.4-0.8) or born in 2009 or later (OR 0.8, 99% CI 0.7-0.9). The campaign averted up to 41,000-56,000 deaths during 2010-13, or 39-57% of the expected deaths nationally. Elimination of measles deaths in India is feasible.

Trends in cause-specific mortality among children aged 5-14 years from 2005 to 2016 in India, China, Brazil, and Mexico: an analysis of nationally representative mortality studies.

BACKGROUND: With global survival increasing for children younger than 5 years of age, attention is required to reduce the approximately 1 million deaths of children aged 5-14 years occurring every year. Causes of death at these ages remain poorly documented. We aimed to explore trends in mortality by causes of death in India, China, Brazil, and Mexico, which are home to about 40% of the world's children aged 5-14 years and experience more than 200 000 deaths annually at these ages. METHODS: We examined data on 244 401 deaths in children aged 5-14 years from four nationally representative data sources that obtained direct distributions of causes of death: the Indian Million Death Study, the Chinese Disease Surveillance Points, mortality data from the Mexican Instituto Nacional de Estadística y Geografía, and mortality data from the Brazilian Institute of Geography and Statistics. We present data on 12 main disease groups in all countries, with breakdown by communicable and nutritional diseases, non-communicable diseases, injuries, and ill-defined causes. To calculate age-specific and sex-specific death rates for each cause, we applied the national cause of death distribution to the UN mortality envelopes for 2005-16 for each country. FINDINGS: Unlike Brazil, China, and Mexico, communicable diseases still account for nearly half of deaths in India in children aged 5-14 years (73 920 [46·1%] of 160 330 estimated deaths in 2016). In 2016, India had the highest death rates in nearly every category, including from communicable diseases. Fast declines among girls in communicable disease mortality narrowed the gap by 2016 with boys in India (32·6 deaths per 100 000 girls vs 26·2 per 100 000 boys) and China (1·7 vs 1·5). In China, injuries accounted for the greatest proportions of deaths (20 970 [53·2%] of 39 430 estimated deaths, in which drowning was a leading cause). The homicide death rate at ages 10-14 years was higher for boys than for girls in Brazil, increasing annually by an average of 0·7% (0·3-1·1). In India and China, the suicide death rates were higher for girls than for boys at ages 10-14 years. By contrast, in Mexico it was higher for boys than for girls, increasing annually by an average of 2·8% (2·0-3·6). Deaths from transport injuries, drowning, and cancer are common in all four countries, with transport accidents among the top three causes of death for both sexes in all countries, except for Indian girls, and cancer in the top three causes for both sexes in Mexico, Brazil, and China. INTERPRETATION: Most of the deaths that occurred between 2005 and 2016 in children aged 5-14 years in India, China, Brazil, and Mexico arose from preventable or treatable conditions. This age group is important for extending some of the global disease-specific targets developed for children younger than 5 years of age. Interventions to control non-communicable diseases and injuries and to strengthen cause of death reporting systems are also required. FUNDING: WHO and the University of Toronto Connaught Global Challenge.

Risk factors for serious outcomes associated with influenza illness in high- versus low- and middle-income countries: Systematic literature review and meta-analysis.

AIM: To determine factors associated with a serious outcome (hospital admission or severe outcome: critical care or death) and associated with illness caused by laboratory-confirmed influenza, with a specific interest in low- and middle-income countries (LMIC). METHOD: Databases were searched on 11 March 2016 for reports of influenza and factors associated with mortality or morbidity in humans, with no language restrictions. Pooled risks were estimated using random-effects models. RESULTS: Despite the heterogeneity of results across studies, known risk factors for serious disease were associated with both hospital admission and severe outcomes (critical care and/or death). In LMIC, but not in high income countries (HIC), pregnant women, people with HIV/AIDS and children < 5 years old (compared with older children) were at increased risk of a severe outcome. Also, although all patients with neurological conditions were at higher risk of severe outcomes than those without, children were at higher risk than adults and children who lived in a LMIC were at significantly higher risk than those living in HIC. Adults were more likely than children to suffer a severe outcome if they had diabetes or a hematologic condition, were obese or had liver disease. Asthma is a risk factor for hospital admission but not for severe outcomes. CONCLUSION: Known risk factors for serious disease remain important predictors of hospital admission and severe outcomes with few differences between HIC and LMIC countries. These differences likely reflect differences in health-seeking behaviours and health services, but high heterogeneity between studies limits conclusions about the effect size.

Herd effect from influenza vaccination in non-healthcare settings: a systematic review of randomised controlled trials and observational studies.

Influenza vaccination programmes are assumed to have a herd effect and protect contacts of vaccinated persons from influenza virus infection. We searched MEDLINE, EMBASE, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), Global Health and the Cochrane Central Register of Controlled Trials (CENTRAL) from inception to March 2014 for studies assessing the protective effect of influenza vaccination vs no vaccination on influenza virus infections in contacts. We calculated odds ratios (ORs) and 95% confidence intervals (CIs) using a random-effects model. Of 43,082 screened articles, nine randomised controlled trials (RCTs) and four observational studies were eligible. Among the RCTs, no statistically significant herd effect on the occurrence of influenza in contacts could be found (OR: 0.62; 95% CI: 0.34-1.12). The one RCT conducted in a community setting, however, showed a significant effect (OR: 0.39; 95% CI: 0.26-0.57), as did the observational studies (OR: 0.57; 95% CI: 0.43-0.77). We found only a few studies that quantified the herd effect of vaccination, all studies except one were conducted in children, and the overall evidence was graded as low. The evidence is too limited to conclude in what setting(s) a herd effect may or may not be achieved.

Facility Delivery, Postnatal Care and Neonatal Deaths in India: Nationally-Representative Case-Control Studies.

OBJECTIVE: Clinical studies demonstrate the efficacy of interventions to reduce neonatal deaths, but there are fewer studies of their real-life effectiveness. In India, women often seek facility delivery after complications arise, rather than to avoid complications. Our objective was to quantify the association of facility delivery and postnatal checkups with neonatal mortality while examining the "reverse causality" in which the mothers deliver at a health facility due to adverse perinatal events. METHODS: We conducted nationally representative case-control studies of about 300,000 live births and 4,000 neonatal deaths to examine the effect of, place of delivery and postnatal checkup on neonatal mortality. We compared neonatal deaths to all live births and to a subset of live births reporting excessive bleeding or obstructed labour that were more comparable to cases in seeking care. FINDINGS: In the larger study of 2004-8 births, facility delivery without postnatal checkup was associated with an increased odds of neonatal death (Odds ratio = 2.5; 99% CI 2.2-2.9), especially for early versus late neonatal deaths. However, use of more comparable controls showed marked attenuation (Odds ratio = 0.5; 0.4-0.5). Facility delivery with postnatal checkup was associated with reduced odds of neonatal death. Excess risks were attenuated in the earlier study of 2001-4 births. CONCLUSION: The combined effect of facility deliveries with postnatal checks ups is substantially higher than just facility delivery alone. Evaluation of the real-life effectiveness of interventions to reduce child and maternal deaths need to consider reverse causality. If these associations are causal, facility delivery with postnatal check up could avoid about 1/3 of all neonatal deaths in India (~100,000/year).

Zanamivir versus trivalent split virus influenza vaccine: a pilot randomized trial.

BACKGROUND: Healthcare workers may be exposed to people with respiratory viral infections more often than other working adults. Understanding the risk and the effectiveness of different preventive measures is of great importance. OBJECTIVES: To estimate adherence to prophylactic antiviral medication for a full influenza season, to the compare efficacy of antiviral prophylaxis to that of the seasonal influenza vaccine and to identify exposures that increase risk of acute respiratory illnesses (ARI) in healthy adults. METHODS: Participants were randomized 1:2 to receive the 2008-2009 influenza vaccine or daily prophylaxis with 10 mg of zanamivir during the season. Web-based questionnaires collected information on demographics, symptoms, exposures, medication use and side effects. RESULTS: Sixty-four healthy adults were recruited in November 2008. Three of 40 active participants discontinued zanamivir due to side effects; the remaining 37 took >85% of scheduled doses for a median of 121 days. Symptomatic, laboratory-confirmed influenza was detected in one person randomized to zanamivir (2·5%) and 2/20 (10%) who received the vaccine (P = 0·25). Forty-seven participants reported 109 episodes of ARI. Factors associated with an ARI were exposure to a spouse (OR 7·2), child (OR 2·4) or patient (OR 2·0) with symptoms of an ARI in the previous 7 days. CONCLUSIONS: Breakthrough influenza infection occurred in both vaccinated participants and those receiving antiviral prophylaxis. Most adults were willing and able to comply with season-long prophylaxis. Report of recent exposure to family members and patients with an ARI increased the risk of developing an ARI in healthy adults.

Populations at risk for severe or complicated Avian Influenza H5N1: a systematic review and meta-analysis.

BACKGROUND: Little is known about risk factors for severe outcomes in patients infected with H5N1 and no systematic review has been conducted. Understanding risk factors is an important step for prioritizing prophylaxis or treatment in the event of a pandemic. OBJECTIVES: To systematically evaluate risk factors for severe outcomes in patients with avian influenza H5N1 infection. DATA SOURCES: MEDLINE, EMBASE, CINAHL, GlobalHealth, and CENTRAL through March 2011. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Observational studies of any design published in English, French, Spanish, German or Korean that reported on risk factor-outcome combinations of interest in participants with confirmed H5N1 infections. Outcomes considered included death, ventilator support, hospital and ICU admission, pneumonia, and composite outcomes. STUDY APPRAISAL: Risk of bias was assessed using the Newcastle-Ottawa scale (NOS). RESULTS: We identified 20 studies reporting on 999 patients infected with H5N1. The majority of studies (n = 14, 70%) were at intermediate risk of bias, i.e. 4-6 points on the NOS. Females were at increased risk of death (OR 1.75, 95% CI 1.27-2.44), while young age, in particular <5 years of age (OR 0.44, 95% CI 0.25-0.79 for death), was protective. Data on traditional risk factors was scarce and requires further studies. Another major limitation in the published literature was lack of adjustment for confounders. INTERPRETATION: Females were at increased risk for complications following H5N1 infection while young age protected against severe outcomes. Research on traditional risk factors was limited and is required.

Populations at risk for severe or complicated influenza illness: systematic review and meta-analysis.

OBJECTIVE: To evaluate risk factors for severe outcomes in patients with seasonal and pandemic influenza. DESIGN: Systematic review. STUDY SELECTION: Observational studies reporting on risk factor-outcome combinations of interest in participants with influenza. Outcomes included death, ventilator support, admission to hospital, admission to an intensive care unit, pneumonia, and composite outcomes. DATA SOURCES: Medline, Embase, CINAHL, Global Health, and the Cochrane Central Register of Controlled Trials to March 2011. RISK OF BIAS ASSESSMENT: Newcastle-Ottawa scale to assess the risk of bias. GRADE framework to evaluate the quality of evidence. RESULTS: 63 537 articles were identified of which 234 with a total of 610 782 participants met the inclusion criteria. The evidence supporting risk factors for severe outcomes of influenza ranged from being limited to absent. This was particularly relevant for the relative lack of data for non-2009 H1N1 pandemics and for seasonal influenza studies. Limitations in the published literature included lack of power and lack of adjustment for confounders was widespread: adjusted risk estimates were provided for only 5% of risk factor-outcome comparisons in 39 of 260 (15%) studies. The level of evidence was low for "any risk factor" (odds ratio for mortality 2.77, 95% confidence interval 1.90 to 4.05 for pandemic influenza and 2.04, 1.74 to 2.39 for seasonal influenza), obesity (2.74, 1.56 to 4.80 and 30.1, 1.74 to 2.39), cardiovascular diseases (2.92, 1.76 to 4.86 and 1.97, 1.06 to 3.67), and neuromuscular disease (2.68, 1.91 to 3.75 and 3.21, 1.84 to 5.58). The level of evidence was very low for all other risk factors. Some well accepted risk factors such as pregnancy and belonging to an ethnic minority group could not be identified as risk factors. In contrast, women who were less than four weeks post partum had a significantly increased risk of death from pandemic influenza (4.43, 1.24 to 15.81). CONCLUSION: The level of evidence to support risk factors for influenza related complications is low and some well accepted risk factors, including pregnancy and ethnicity, could not be confirmed as risks. Rigorous and adequately powered studies are needed.

CXCR3-deficiency protects influenza-infected CCR5-deficient mice from mortality.

Mice lacking the chemokine receptor CCR5 are susceptible to mortality from a normally non-lethal influenza infection. Here we found that CXCR3-deficiency rescued CCR5-deficient (CCR5(-/-)) mice from influenza-induced mortality. The number of mononuclear phagocytes in the airways was transiently increased in CCR5(-/-) mice but not in CXCR3-CCR5 double-deficient mice. Antigen-specific CXCR3-CCR5 double-deficient CD8 effector cells were less efficient at entering the airways compared with WT or CCR5(-/-) CD8 effector cells. The decrease in inflammatory cell infiltrates in CXCR3-CCR5 double-deficient-infected mice correlated with a decrease in CCL2 and IFN-gamma production in the airways. Finally, CXCR3-CCR5 double-deficient mice that survived the primary viral challenge were protected from a lethal secondary challenge, indicating that T-cell-mediated protective memory was not compromised in mice lacking these chemokine receptors. In conclusion, CXCR3-deficiency attenuated the lethal cellular immune response in CCR5(-/-) influenza-infected mice without hindering viral clearance or long-term immunity.

Neonate-primed CD8+ memory cells rival adult-primed memory cells in antigen-driven expansion and anti-viral protection.

Immunizations early in life, when the host is most susceptible to infection, allow protective immunological memory to develop. Decreasing the dose of Cas-Br-E murine leukemia virus when priming neonatal mice results in adult-like, Type 1 protective responses, but the resulting memory cell populations are smaller than after adult priming. After secondary challenge, virus-specific CD8+ memory cell populations expand twice as much in neonate-primed mice as in adult-primed mice. We found that when equivalent numbers of virus-specific cells were transferred into virus-susceptible mice, protection from disease was similar whether donor, immune mice were primed as neonates or adults, and IL-4 did not alter in vivo virus-specific CD8+ memory cell effector function. Hence, neonate-primed CD8+ cells develop into memory cells that rival adult-primed cells in proliferation and effector function.

Enhanced type 1 immunity after secondary viral challenge in mice primed as neonates.

The goal of infant immunization against viral infection is to develop protective long term memory responses. Priming neonatal mice with a low dose of Cas-Br-E murine leukemia virus (Cas) results in adult-like, type 1 protective responses. However, other studies suggest that Ag priming of neonates leads to an increase in type 2 secondary responses even when primary responses were type 1. We assessed whether type 1 CD8+ T cell-mediated responses developed in murine neonates are maintained after secondary challenge with Cas in adulthood. Despite the induction of significant anti-viral CD8+-mediated cytotoxic T lymphocyte and IFN-gamma responses, initial neonatal priming led to a lower frequency of virus-specific T cells compared with adult priming. Adult frequencies were reached in mice primed as neonates only after secondary challenge in adulthood. A nonspecific and transient CD4+-mediated IL-4 response was present in all groups after secondary challenge with Cas or medium, indicating that this rise in type 2 cytokine production was not unique to mice that had been primed as neonates. Rather, type 1 anti-viral memory CD8+ T cell responses developed in neonatal mice are stable, protective, and enhanced after secondary challenge.