Sociodemographic factors and clinical conditions associated to hospitalization in influenza A (H1N1) 2009 virus infected patients in Spain, 2009-2010

The association between socioeconomic status and pandemic influenza: Systematic review and meta-analysis

BACKGROUND

The objective of this study is to document whether and to what extent there is an association between socioeconomic status (SES) and disease outcomes in the last five influenza pandemics.

METHODS/PRINCIPLE FINDINGS

The review included studies published in English, Danish, Norwegian and Swedish. Records were identified through systematic literature searches in six databases. We summarized results narratively and through meta-analytic strategies. Only studies for the 1918 and 2009 pandemics were identified. Of 14 studies on the 2009 pandemic including data on both medical and social risk factors, after controlling for medical risk factors 8 demonstrated independent impact of SES. In the random effect analysis of 46 estimates from 35 studies we found a pooled mean odds ratio of 1.4 (95% CI: 1.2-1.7, p < 0.001), comparing the lowest to the highest SES, but with substantial effect heterogeneity across studies,-reflecting differences in outcome measures and definitions of case and control samples. Analyses by pandemic period (1918 or 2009) and by level of SES measure (individual or ecological) indicated no differences along these dimensions. Studies using healthy controls tended to document that low SES was associated with worse influenza outcome, and studies using infected controls find low SES associated with more severe outcomes. A few studies compared severe outcomes (ICU or death) to hospital admissions but these did not find significant SES associations in any direction. Studies with more unusual comparisons (e.g., pandemic vs seasonal influenza, seasonal influenza vs other patient groups) reported no or negative non-significant associations.

CONCLUSIONS/SIGNIFICANCE

We found that SES was significantly associated with pandemic influenza outcomes with people of lower SES having the highest disease burden in both 1918 and 2009. To prepare for future pandemics, we must consider social vulnerability. The protocol for this study has been registered in PROSPERO (ref. no 87922) and has been published Mamelund et al. (2019).

[Proposal for territorial analysis to face the SARS-CoV-2 pandemic based on the Profile of pneumonia and Influenza in Ecuador 2016-2018]

OBJECTIVE

The present study seeks to analyse sociodemographic determinants related to severe acute respiratory infections (SARI) and calculate the priorization index in the cantons of Ecuador to identify areas probably most vulnerable to COVID-19 transmission.

DESIGN

This descriptive ecological observational study.

SETTING

224 cantons (geographical area) of Ecuador with secondary data sources of hospital information.

PARTICIPANTS

The unit of measurement was 224 cantons of Ecuador, in which analysed morbidity and lethality rates for SARI using hospital release data (2016-2018).

MAIN MEASUREMENTS

Eight sociodemographic indicators were structuralized, and correlation tests applied for a multiple regression model. The priorization index was created with criteria of efficiency, efficacy, effect size (IRR) and equity. Using the sum of the index for each indicator, the priorization score was calculated and localized in a territorial map.

RESULTS

Morbidity associated factors where: school attendance years, urbanization and population density; for mortality resulted: school attendance and ethnics (indigenous) IRR: 1.09 (IC95%:1.06-1.15) and IRR: 1.024 (IC95%:102-1.03) respectively. With lethality where related cantons, with population older than 60 years, IRR: 1.049 (IC95%: 1.03-1.07); 87 cantons had high priority mostly localized in the mountain region and the Morona Santiago Province.

CONCLUSIONS

Morbidity and mortality of SARI in Ecuador are associated to social and demographic factors. Priorization exercises considering these factors permit the identification of vulnerable territories facing respiratory disease propagation. The social determinants characteristic for each territory should be added to known individual factors to analyse the risk and vulnerability for COVID in the population.

Negative Association Between Mediterranean Diet Adherence and COVID-19 Cases and Related Deaths in Spain and 23 OECD Countries: An Ecological Study

In December 2019, the severe acute respiratory syndrome coronavirus 2 (SARS-Cov2) emerged in Wuhan, China, sparking the Coronavirus disease 2019 (COVID-19) pandemic. The high prevalence of nutrition-related COVID-19 risk factors including obesity, type 2 diabetes, and hypertension, suggests that healthy dietary approaches may mitigate COVID-19 related outcomes and possibly SARS-CoV-2 infection. Based on the fundamental role of nutrition in immune function and the well-documented association between Mediterranean diet consumption and risk reduction for chronic diseases that are comorbidities in COVID-19 patients, we hypothesized that there would be a relationship between Mediterranean diet adherence and COVID-19 cases and related deaths. In this perspective, we examined the association between regional adherence to a Mediterranean diet and COVID-19 cases and deaths using an ecological study design. We observed that Mediterranean diet adherence was negatively associated with both COVID-19 cases and related deaths across 17 regions in Spain and that the relationship remained when adjusted for factors of well-being. We also observed a negative association between Mediterranean diet adherence and COVID-19 related deaths across 23 countries when adjusted for factors of well-being and physical inactivity. The anti-inflammatory properties of the Mediterranean diet - likely due to the polyphenol content of the diet - may be a biological basis to explain our findings. However, there are confounding factors unrelated to dietary factors driving COVID-19 cases and related deaths across the regions in Spain and the 23 countries examined in our analysis. Our findings will need to be confirmed and further explored in cohort studies.

Immunological Changes in Pregnancy and Its Relation to COVID-19 Infection

This chapter describes the immunological adaptation to pregnancy. A special focus is drawn on the susceptibility to viral infections, especially COVID-19. Older literature refers to the pregnancy as an immunosuppressive state, while recent studies show an immunomodulation to adapt to the growing semiallograftic fetus. Despite this, pregnant women are not susceptible to all viral infections. Regarding influenza, pregnant women are not more susceptible to the infection, but more severe maternal courses. To prevent this, influenza vaccination is recommended for pregnant women. Based on the available evidence, pregnant patients are also not more susceptible to infection with regard to COVID-19 infection. Yet, more severe courses are described throughout gestation with the onset of obstetrical complications.

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.

Pregnancy as a risk factor for severe outcomes from influenza virus infection: A systematic review and meta-analysis of observational studies

BACKGROUND

Pregnancy is considered to be an important risk factor for severe complications following influenza virus infection. As a consequence, WHO recommendations prioritize pregnant women over other risk groups for influenza vaccination. However, the risk associated with pregnancy has not been systematically quantified.

PURPOSE

Systematic review and meta-analysis of observational studies that reported on pregnancy as a risk factor for severe outcomes from influenza virus infection.

DATA SOURCE

MEDLINE, EMBASE, CINAHL, and CENTRAL up to April 2014.

DATA SELECTION

Studies reporting on outcomes in pregnant women with influenza in comparison to non-pregnant patients with influenza. Outcomes included community-acquired pneumonia, hospitalization, admission to intensive care units (ICU), ventilatory support, and death.

DATA EXTRACTION

Two reviewers conducted independent screening and data extraction. A random effects model was used to obtain risk estimates. Ecological studies were summarized descriptively.

DATA SYNTHESIS

A total of 142 non-ecological and 10 ecological studies were included. The majority of studies (n=136, 95.8%) were conducted during the 2009 influenza A (pH1N1) pandemic. There was a higher risk for hospitalization in pregnant versus non-pregnant patients infected with influenza (odds ratio [OR] 2.44, 95% CI 1.22-4.87), but no significant difference in mortality (OR 1.04, 95% CI 0.81-1.33) or other outcomes. Ecologic studies confirmed the association between hospitalization risk and pregnancy and 4 of 7 studies reported higher mortality rates in pregnant women.

LIMITATIONS

No studies were identified in which follow-up began prior to contact with the healthcare system and lack of adjustment for confounding factors.

CONCLUSIONS

We found that influenza during pregnancy resulted in a higher risk of hospital admission than influenza infection in non-pregnant individuals, but that the risk of mortality following influenza was similar in both pregnant and non-pregnant individuals.

Risk factors associated with hospitalisation for influenza-associated severe acute respiratory illness in South Africa: A case-population study

BACKGROUND

Influenza is a common cause of severe respiratory illness, but risk factors for hospitalisation in low income settings with a high HIV prevalence are not well described. We aimed to assess risk factors associated with influenza-associated severe acute respiratory illness (SARI) hospitalisation in South Africa.

METHODS

We conducted a case-population study using data on risk conditions in patients hospitalised with SARI and the national prevalence of these conditions. Data on hospitalised cases were from the national SARI surveillance program while data on the referent population were from the latest national census or health and demographic surveillance surveys.

FINDINGS

From 2009 to 2012, we identified 3646 (7.9%) of 46,031 enrolled cases of SARI that were associated with influenza infection. Risk factors associated with hospitalisation included previous history of smoking [case-population ratio (CPR) 3.82, 95% confidence interval (CI) 3.5-4.16], HIV infection (CPR 3.61, 95% CI 3.5-3.71), asthma (CPR 2.45, 95% CI 2.19-2.73), previous history of hospital admission in the past 12months (CPR 2.07, 95% CI 1.92-2.23), and tuberculosis (CPR 1.85, 95% CI 1.68-2.02). When stratified by age, there is increased risk of hospitalisation in those ⩽5yearsof age (CPR 3.07, 95% CI 2.93-3.21) and among those 35yearsof age and above (CPR 1.23, 95% CI 1.28-1.18). Male sex (CPR 0.85, 95% CI 0.82-0.88) and completion of pneumococcal conjugate vaccination schedule in children <5yearsof age (CPR 0.74, 95% CI 0.71-0.77) were associated with decreased risk of hospitalisation.

CONCLUSION

These results identify groups at high-risk for severe influenza who should be considered potential targets for influenza vaccination in South Africa and similar settings.

High Body Mass Index as a Risk Factor for Hospitalization Due to Influenza: A Case-Control Study

INTRODUCTION

Obesity has emerged as a significant independent predictor of severity in pandemic influenzaA (H1N1)pdm09. The aim of this study was to investigate the association between body mass index (BMI) and the risk of hospitalization due to influenza.

METHODS

Hospitalized patients (n=755) with laboratory-confirmed influenza were individually matched by age, admission/visit date, and province with an outpatient (n=783) with laboratory-confirmed influenza and an outpatient control (n=950). We compared the BMI using conditional logistic regression adjusted for potential confounding factors (aOR). The population attributable fraction (PAF) was calculated.

RESULTS

A higher BMI was associated with an increased risk of hospitalization compared to both outpatient cases (aOR=1.11; 95%CI: 1.07-1.16) and outpatient controls (aOR=1.04; 95%CI: 1.01-1.07). Compared with normal weight, obesity type I, obesity type II and obesity type III was associated with a greater likelihood of hospitalization compared with outpatient cases (aOR=1.85, 95%CI: 1.05-3.26; aOR=5.24, 95%CI: 1.94-14.15 and aOR=44.38, 95%CI: 4.47-440.5). Compared with normal weight, obesity type II and obesity type III was associated with a greater likelihood of hospitalization compared with outpatient controls (aOR=4.37, 95%CI: 1.79-10.69 and aOR=4.95, 95%CI: 1.45-16.87). In persons without influenza vaccination, all categories of BMI≥30kg/m(2) were associated with a greater likelihood of hospitalization compared with normal weight in both outpatient cases and outpatient controls. The PAF of hospitalization by influenza due to BMI ranged from 21.9% to 8.5%; in the case of unvaccinated against influenza between 20.5% to 16.9%.

CONCLUSION

A high BMI is associated with an increased risk of hospitalization due to influenza. High percentage of hospital admissions are attributable to their BMI, especially in non vaccinated.

No Major Host Genetic Risk Factor Contributed to A(H1N1)2009 Influenza Severity

While most patients affected by the influenza A(H1N1) pandemic experienced mild symptoms, a small fraction required hospitalization, often without concomitant factors that could explain such a severe course. We hypothesize that host genetic factors could contribute to aggravate the disease. To test this hypothesis, we compared the allele frequencies of 547,296 genome-wide single nucleotide polymorphisms (SNPs) between 49 severe and 107 mild confirmed influenza A cases, as well as against a general population sample of 549 individuals. When comparing severe vs. mild influenza A cases, only one SNP was close to the conventional p = 5×10⁻⁸. This SNP, rs28454025, sits in an intron of the GSK233 gene, which is involved in a neural development, but seems not to have any connections with immunological or inflammatory functions. Indirectly, a previous association reported with CD55 was replicated. Although sample sizes are low, we show that the statistical power in our design was sufficient to detect highly-penetrant, quasi-Mendelian genetic factors. Hence, and assuming that rs28454025 is likely to be a false positive, no major genetic factor was detected that could explain poor influenza A course.

Social class based on occupation is associated with hospitalization for A(H1N1)pdm09 infection. Comparison between hospitalized and ambulatory cases

This study aimed to analyse the existence of an association between social class (categorized by type of occupation) and the occurrence of A(H1N1)pmd09 infection and hospitalization for two seasons (2009-2010 and 2010-2011). This multicentre study compared ambulatory A(H1N1)pmd09 confirmed cases with ambulatory controls to measure risk of infection, and with hospitalized A(H1N1)pmd09 confirmed cases to asses hospitalization risk. Study variables were: age, marital status, tobacco and alcohol use, pregnancy, chronic obstructive pulmonary disease, chronic respiratory failure, cardiovascular disease, diabetes, chronic liver disease, body mass index >40, systemic corticosteroid treatment and influenza vaccination status. Occupation was registered literally and coded into manual and non-manual worker occupational social class groups. A conditional logistic regression analysis was performed. There were 720 hospitalized cases, 996 ambulatory cases and 1062 ambulatory controls included in the study. No relationship between occupational social class and A(H1N1)pmd09 infection was found [adjusted odds ratio (aOR) 0·97, 95% confidence interval (CI) 0·74-1·27], but an association (aOR 1·53, 95% CI 1·01-2·31) between occupational class and hospitalization for A(H1N1)pmd09 was observed. Influenza vaccination was a protective factor for A(H1N1)pmd09 infection (aOR 0·41, 95% CI 0·23-0·73) but not for hospitalization. We conclude that manual workers have the highest risk of hospitalization when infected by influenza than other occupations but they do not have a different probability of being infected by influenza.

An estimate of the incidence of influenza-like illness during the influenza pandemic of 2009

INTRODUCTION

The influenza pandemic of 2009 had a great social impact. Many health resources were devoted to the care, prevention and surveillance of this disease. Epidemiological surveillance is based on the reporting of cases of influenza-like illness (ILI) and confirmed influenza cases. The objective was to estimate the true incidence of ILI during the influenza pandemic of 2009.

METHODS

The capture-recapture method was applied during the month of highest influenza incidence in Castellón. Two notification systems were used: (i)electronic reporting of Notifiable Diseases (ND), and (ii)laboratory-based (LAB) data collection. Estimates were made by stratifying by age group and week. Independence coefficients were calculated for those strata.

RESULTS

No dependence was found between stratification variables and the reporting system. A total of 7,181 ND cases and 524 LAB cases were identified, of which 211 were recorded in both systems. The estimated total of cases was 17,785 in a single month. In the study period, almost 4% of people in the area suffered flu symptoms (cumulative incidence), with 1% being affected each day (daily prevalence). The sensitivity of the ND system was 40%, i.e., the percentage of patients seeking primary care.

CONCLUSIONS

To obtain an estimate of the actual incidence of influenza-like illness in the population during a pandemic period, the number of medical consultations should be multiplied by a factor of 2.5. This factor is lower than that estimated for periods without pandemic alert.

Epidemiology of severe influenza outcomes among adult patients with obesity in Detroit, Michigan, 2011

We conducted a retrospective cohort study to evaluate the impact of obesity on influenza disease severity. Individuals with obesity were more likely to have lower pulmonary disease manifestations [OR=1·97 (95% CI 1·05, 3·69), P=0·03] and to be admitted to an inpatient ward [OR=2·93 (95% CI 1·50, 5·71), P=0·002] when compared with non-obese individuals. Among admitted individuals, persons with obesity were more likely to require a lengthy hospital stay [OR=3·86 (95% CI 1·03, 14·42), P=0·045]. Five of the six deaths in study subjects occurred in persons with obesity.

Severe acute respiratory infections in the postpandemic era of H1N1

PURPOSE OF REVIEW

Shortly after the advent of severe acute respiratory syndrome and the avian influenza, the emergence of the influenza A(H1N1)2009 pandemic caused significant vibrations to the public health authorities and stressed the health systems worldwide. We sought to investigate whether this experience has altered our knowledge and our current and future practice on the management of severe acute respiratory infections (SARI) and community-acquired pneumonia.

RECENT FINDINGS

A changing epidemiology was demonstrated, with obesity and pregnancy beyond established risk groups for influenza A, other clinical syndromes beyond primary viral pneumonia, possible coinfections by other viral beyond bacterial pathogens and a disappointing performance of all available severity assessment tools. On the treatment topic, accumulating evidence suggesting worse outcomes argues against the use of corticosteroids, but some noninvasive ventilating modalities require further assessment.

SUMMARY

The recent influenza A(H1N1)2009 pandemic has highlighted our weaknesses relating to the diagnosis and assessment of severity of SARI, compromising early treatment and ultimate outcomes; further research based on this experience will help to improve prognosis and boost our future preparedness. An important message is the necessity of international collaboration for the rapid dissemination of locally acquired knowledge.

Epidemiological characteristics and underlying risk factors for mortality during the autumn 2009 pandemic wave in Mexico

Background

Elucidating the role of the underlying risk factors for severe outcomes of the 2009 A/H1N1 influenza pandemic could be crucial to define priority risk groups in resource-limited settings in future pandemics.

Methods

We use individual-level clinical data on a large series of ARI (acute respiratory infection) hospitalizations from a prospective surveillance system of the Mexican Social Security medical system to analyze clinical features at presentation, admission delays, selected comorbidities and receipt of seasonal vaccine on the risk of A/H1N1-related death. We considered ARI hospitalizations and inpatient-deaths, and recorded demographic, geographic, and medical information on individual patients during August-December, 2009.

Results

Seasonal influenza vaccination was associated with a reduced risk of death among A/H1N1 inpatients (OR = 0.43 (95% CI: 0.25, 0.74)) after adjustment for age, gender, geography, antiviral treatment, admission delays, comorbidities and medical conditions. However, this result should be interpreted with caution as it could have been affected by factors not directly measured in our study. Moreover, the effect of antiviral treatment against A/H1N1 inpatient death did not reach statistical significance (OR = 0.56 (95% CI: 0.29, 1.10)) probably because only 8.9% of A/H1N1 inpatients received antiviral treatment. Moreover, diabetes (OR = 1.6) and immune suppression (OR = 2.3) were statistically significant risk factors for death whereas asthmatic persons (OR = 0.3) or pregnant women (OR = 0.4) experienced a reduced fatality rate among A/H1N1 inpatients. We also observed an increased risk of death among A/H1N1 inpatients with admission delays >2 days after symptom onset (OR = 2.7). Similar associations were also observed for A/H1N1-negative inpatients.

Conclusions

Geographical variation in identified medical risk factors including prevalence of diabetes and immune suppression may in part explain between-country differences in pandemic mortality burden. Furthermore, access to care including hospitalization without delay and antiviral treatment and are also important factors, as well as vaccination coverage with the 2008–09 trivalent inactivated influenza vaccine.