Estimates of excess medically attended acute respiratory infections in periods of seasonal and pandemic influenza in Germany from 2001/02 to 2010/11

Trends in respiratory virus circulation following COVID-19-targeted nonpharmaceutical interventions in Germany, January - September 2020: Analysis of national surveillance data

BACKGROUND

During the initial COVID-19 response, Germany's Federal Government implemented several nonpharmaceutical interventions (NPIs) that were instrumental in suppressing early exponential spread of SARS-CoV-2. NPI effect on the transmission of other respiratory viruses has not been examined at the national level thus far.

METHODS

Upper respiratory tract specimens from 3580 patients with acute respiratory infection (ARI), collected within the nationwide German ARI Sentinel, underwent RT-PCR diagnostics for multiple respiratory viruses. The observation period (weeks 1-38 of 2020) included the time before, during and after a far-reaching contact ban. Detection rates for different viruses were compared to 2017-2019 sentinel data (15350 samples; week 1-38, 11823 samples).

FINDINGS

The March 2020 contact ban, which was followed by a mask mandate, was associated with an unprecedented and sustained decline of multiple respiratory viruses. Among these, rhinovirus was the single agent that resurged to levels equalling those of previous years. Rhinovirus rebound was first observed in children, after schools and daycares had reopened. By contrast, other nonenveloped viruses (i.e. gastroenteritis viruses reported at the national level) suppressed after the shutdown did not rebound.

INTERPRETATION

Contact restrictions with a subsequent mask mandate in spring may substantially reduce respiratory virus circulation. This reduction appears sustained for most viruses, indicating that the activity of influenza and other respiratory viruses during the subsequent winter season might be low,whereas rhinovirus resurgence, potentially driven by transmission in educational institutions in a setting of waning population immunity, might signal predominance of rhinovirus-related ARIs.

FUNDING

Robert Koch-Institute and German Ministry of Health.

Recommendations for respiratory syncytial virus surveillance at national level

Respiratory syncytial virus (RSV) is a common cause of acute lower respiratory tract infections and hospitalisations among young children and is globally responsible for many deaths in young children, especially in infants aged <6 months. Furthermore, RSV is a common cause of severe respiratory disease and hospitalisation among older adults. The development of new candidate vaccines and monoclonal antibodies highlights the need for reliable surveillance of RSV. In the European Union (EU), no up-to-date general recommendations on RSV surveillance are currently available. Based on outcomes of a workshop with 29 European experts in the field of RSV virology, epidemiology and public health, we provide recommendations for developing a feasible and sustainable national surveillance strategy for RSV that will enable harmonisation and data comparison at the European level. We discuss three surveillance components: active sentinel community surveillance, active sentinel hospital surveillance and passive laboratory surveillance, using the EU acute respiratory infection and World Health Organization (WHO) extended severe acute respiratory infection case definitions. Furthermore, we recommend the use of quantitative reverse transcriptase PCR-based assays as the standard detection method for RSV and virus genetic characterisation, if possible, to monitor genetic evolution. These guidelines provide a basis for good quality, feasible and affordable surveillance of RSV. Harmonisation of surveillance standards at the European and global level will contribute to the wider availability of national level RSV surveillance data for regional and global analysis, and for estimation of RSV burden and the impact of future immunisation programmes.

Recommendations for developing a feasible and sustainable national surveillance strategy for respiratory syncytial virus that will enable harmonisation and data comparison at the European level.https://bit.ly/3rWUOOI

Severe Illnesses Associated With Outbreaks of Respiratory Syncytial Virus and Influenza in Adults

Background

Recent reports have described the contribution of adult respiratory syncytial virus (RSV) infections to the use of advanced healthcare resources and death.

Methods

Data regarding patients aged ≥18 years admitted to any of Maryland’s 50 acute-care hospitals were evaluated over 12 consecutive years (2001–2013). We examined RSV and influenza (flu) surveillance data from the US National Respiratory and Enteric Virus Surveillance System and the Centers for Disease Control and Prevention and used this information to define RSV and flu outbreak periods in the Maryland area. Outbreak periods consisted of consecutive individual weeks during which at least 10% of RSV and/or flu diagnostic tests were positive. We examined relationships of RSV and flu outbreaks to occurrence of 4 advanced medical outcomes (hospitalization, intensive care unit admission, intubated mechanical ventilation, and death) due to medically attended acute respiratory illness (MAARI).

Results

Occurrences of all 4 MAARI-related hospital advanced medical outcomes were consistently greater for all adult ages during RSV, flu, and combined RSV–flu outbreak periods compared to nonoutbreak periods and tended to be greatest in adults aged ≥65 years during combined RSV–flu outbreak periods. Rate ratios for all 4 MAARI-related advanced medical outcomes ranged from 1.04 to 1.38 during the RSV, flu, or combined RSV–flu outbreaks compared to the nonoutbreak periods, with all 95% lower confidence limits >1.

Conclusions

Both RSV and flu outbreaks were associated with surges in MAARI-related advanced medical outcomes (hospitalization, intensive care unit admission, intubated mechanical ventilation, and death) for adults of all ages.

Long-lasting cough in an adult German population: incidence, symptoms, and related pathogens

Studies of the incidence of pertussis in adults have shown that it accounts for only 5–15% cases of prolonged coughing. We assessed the burden of suffering related to prolonged coughing and tried to identify further causative agents. Based on a sentinel study with 35 general practitioners in two German cities (Krefeld, Rostock), with 3,946 patients fulfilling the inclusion criteria, we estimated the incidence of prolonged coughing in adults. In 975 of these outpatients, PCR and/or serology for adenovirus, Bordetella pertussis and B. parapertussis, human metapneumovirus, influenza virus A and rhinovirus, parainfluenza virus, Mycoplasma pneumonia, and respiratory syncytial virus (RSV) were performed. Treatment data were extracted for a subgroup of 138 patients. Descriptive statistics, including Kaplan–Maier curves were generated. Yearly incidence ranged between 1.4 and 2.1% per population in the two cities. Adult patients sought medical attention only after a median of 3 weeks of coughing. Irrespective of smoking and unrelated to the identified pathogens, the median duration of coughing was 6 weeks, with an interquartile range of 4–11 weeks. In 48.3% of patients, possible pathogens were identified, among which adenovirus (15.1%), RSV (7.5%), B. pertussis (5.6%), and influenza viruses (4.0%) were most often found. Symptoms were not indicative of a specific agent and a total of 64% of patients received antibiotics. Prolonged adult coughing requiring medical attention prompts substantial healthcare use. Apart from B. pertussis, a broad range of pathogens was associated with the symptoms. However, patients sought medical attention too late to guide efficacious therapeutic interventions using the diagnostic tests.

Establishing an ICD-10 code based SARI-surveillance in Germany - description of the system and first results from five recent influenza seasons

BACKGROUND

Syndromic surveillance of severe acute respiratory infections (SARI) is important to assess seriousness of disease as recommended by WHO for influenza. In 2015 the Robert Koch Institute (RKI) started to collaborate with a private hospital network to develop a SARI surveillance system using case-based data on ICD-10 codes. This first-time description of the system shows its application to the analysis of five influenza seasons.

METHODS

Since week 40/2015, weekly updated anonymized data on discharged patients overall and on patients with respiratory illness including ICD-10 codes of primary and secondary diagnoses are transferred from the network data center to RKI. Retrospective datasets were also provided. Our descriptive analysis is based on data of 47 sentinel hospitals collected between weeks 1/2012 to 20/2016. We applied three different SARI case definitions (CD) based on ICD-10 codes for discharge diagnoses of respiratory tract infections (J09 - J22): basic CD (BCD), using only primary diagnoses; sensitive CD (SCD), using primary and secondary diagnoses; timely CD (TCD), using only primary diagnoses of patients hospitalized up to one week. We compared the CD with regard to severity, age distribution and timeliness and with results from the national primary care sentinel system.

RESULTS

The 47 sentinel hospitals covered 3.6% of patients discharged from all German hospitals in 2013. The SCD comprised 2.2 times patients as the BCD, and 3.6 times as many as the TCD. Time course of SARI cases corresponded well to results from primary care surveillance and influenza virus circulation. The patients fulfilling the TCD had been completely reported after 3 weeks, which was fastest among the CD. The proportion of SARI cases among patients was highest in the youngest age group of below 5-year-olds. However, the age group 60 years and above contributed most SARI cases. This was irrespective of the CD used.

CONCLUSIONS

In general, available data and the implemented reporting system are appropriate to provide timely and reliable information on SARI in inpatients in Germany. Our ICD-10-based approach proved to be useful for fulfilling requirements for SARI surveillance. The exploratory approach gave valuable insights in data structure and emphasized the advantages of different CD.

[Influenza and community acquired pneumonia in German primary care]

Influenza and community-acquired pneumonia (CAP) impose a considerable annual burden on the German primary care system. Yet there is a lack of epidemiological data from the country's outpatient sector on groups at risk as well as on the complications of these diseases.The Robert Koch Institute (RKI) initiated the study to identify population groups at increased risk for influenza or CAP as well as related comorbidities and sequelae. We present the methodology of the study and the descriptive analysis of the patients.ICD-10-based data was collected in 89 primary health care practices between January 2012 and April 2015 using a data extraction tool developed on behalf of the RKI. Case-based anonymized information was recorded for all patients in whom influenza, CAP or other acute respiratory infections (ARI) were diagnosed. For each patient information on all diagnoses including the date were retrospectively and prospectively collected (each for six months) as well as age, sex and influenza vaccination.Data on 156,803 patients with ARI was collected, of them 7909 patients with influenza (within influenza waves) and 8528 patients with CAP diagnoses. Influenza diagnoses showed a strong seasonal pattern and captured annual influenza waves in Germany. Of the influenza cases 1.6 % had a following diagnosis of CAP within 30 days. Age-specific prevalence of chronic diseases such as asthma and diabetes was significantly higher in the study population as compared to the German population.The developed tool delivers in a standardized fashion ICD-10-coded epidemiological data on population-based burden of influenza and CAP in Germany. As the descriptive analysis showed, the collected dataset is a reliable and solid basis for the further investigations of the study questions.

[Evaluation of an ICD-10-based electronic surveillance of acute respiratory infections (SEEDARI) in Germany]

BACKGROUND

Every year epidemic waves of influenza and other acute respiratory infections (ARIs) cause a highly variable burden of disease in the population. Thus, assessment of the situation and adaptation of prevention strategies have to rely on real time syndromic surveillance.

OBJECTIVE

We have established an ICD-10-based electronic system allowing rapid capture and transmission of information on ARI (SEED^ARI), in Germany. Here we report the evaluation of this new system based on results of the syndromic and virologic surveillance carried out by the working group on influenza in Germany (AGI).

METHODS

Consultations and ICD10-codes (J00-J22, J44.0 and B34.9) between week 16 in 2009, and week 15 in 2013, were used for comparison with AGI data. The time course and the correlation of weekly estimates of the incidence of medically attended ARI (MAARI) and ARI/100 consultations were analyzed for the different surveillance systems.

RESULTS

The number of participating medical practices in SEED^ARI almost doubled from 2009 (n = 65) to 2013 (n = 111). A total of almost 6.8 million consultations and 465,006 diagnosed ARIs were transmitted. The comparison of weekly estimated incidence of MAARI per 100,000 capita derived from SEED^ARI and the results of the AGI showed high statistical correlation (Spearman correlation coefficient r_s = 0,924; n = 209; p < 0,001). The proportion of diagnosed influenza (J09-J11) and the weekly positivity rate from virological surveillance during epidemic waves also showed high correlations.

DISCUSSION

We conclude that SEED^ARI represents a valid system for syndromic influenza surveillance. The case-based ICD-10 approach allows a detailed analysis of the actual situation and also seems suitable for population-based studies.

Is the impact of childhood influenza vaccination less than expected: a transmission modelling study

BACKGROUND

To reduce the burden of severe influenza, most industrialized countries target specific risk-groups with influenza vaccines, e.g. the elderly or individuals with comorbidities. Since children are the main spreaders, some countries have recently implemented childhood vaccination programs to reduce overall virus transmission and thereby influenza disease in the whole population. The introduction of childhood vaccination programs was often supported by modelling studies that predicted substantial incidence reductions. We developed a mathematical transmission model to examine the potential impact of childhood influenza vaccination in Germany, while also challenging established modelling assumptions.

METHODS

We developed an age-stratified SEIR-type transmission model to reproduce the epidemic influenza seasons between 2003/04 and 2013/14. The model was built upon German population counts, contact patterns, and vaccination history and was fitted to seasonal data on influenza-attributable medically attended acute respiratory infections (I-MAARI) and strain distribution using Bayesian methods. As novelties we (i) implemented a stratified model structure enabling seasonal variability and (ii) deviated from the commonly assumed mass-action-principle by employing a phenomenological transmission rate.

RESULTS

According to the model, by vaccinating primarily the elderly over ten seasons 4 million (95% prediction interval: 3.84 - 4.19) I-MAARI were prevented which corresponds to an 8.6% (8.3% - 8.9%) reduction compared to a no-vaccination scenario and a number-needed-to-vaccinate (NNV) to prevent one I-MAARI of 37.1 (35.5 - 38.7). Additional vaccination of 2-10 year-old children at 40% coverage would have led to an overall I-MAARI reduction of 17.8% (17.1 - 18.7%) mostly due to indirect effects with a NNV of 20.7 (19.6 - 21.6). When employing the traditional mass-action-principle, the model predicted a more than 3-fold higher I-MAARI reduction (55.6%) due to childhood vaccination.

CONCLUSION

In Germany, the introduction of routine childhood influenza vaccination could considerably reduce I-MAARI among all age-groups and improve the NNV. However, the predicted impact is much lower compared to previous studies, which is primarily caused by our phenomenological approach to modelling influenza virus transmission.

Estimation of influenza-attributable medically attended acute respiratory illness by influenza type/subtype and age, Germany, 2001/02-2014/15

Background

The total burden of influenza in primary care is difficult to assess. The case definition of medically attended “acute respiratory infection” (MAARI) in the German physician sentinel is sensitive; however, it requires modelling techniques to derive estimates of disease attributable to influenza. We aimed to examine the impact of type/subtype and age.

Methods

Data on MAARI and virological results of respiratory samples (virological sentinel) were available from 2001/02 until 2014/15. We constructed a generalized additive regression model for the periodic baseline and the secular trend. The weekly number of influenza‐positive samples represented influenza activity. In a second step, we distributed the estimated influenza‐attributable MAARI (iMAARI) according to the distribution of types/subtypes in the virological sentinel.

Results

Season‐specific iMAARI ranged from 0.7% to 8.9% of the population. Seasons with the strongest impact were dominated by A(H3), and iMAARI attack rate of the pandemic 2009 (A(H1)pdm09) was 4.9%. Regularly the two child age groups (0‐4 and 5‐14 years old) had the highest iMAARI attack rates reaching frequently levels up to 15%‐20%. Influenza B affected the age group of 5‐ to 14‐year‐old children substantially more than any other age group. Sensitivity analyses demonstrated both comparability and stability of the model.

Conclusion

We constructed a model that is well suited to estimate the substantial impact of influenza on the primary care sector. A(H3) causes overall the greatest number of iMAARI, and influenza B has the greatest impact on school‐age children. The model may incorporate time series of other pathogens as they become available.

Model estimates of the burden of outpatient visits attributable to influenza in the United States

Background

Although many studies have modelled the national burdens of hospitalizations and deaths due to influenza, few studies have considered the outpatient burden. To fill this gap for the United States (US), we applied traditional statistical modelling approaches to time series derived from large medical claims databases held in the private sector.

Methods

We accessed ICD-9-coded office visit data extracted from Truven Health Analytics’ MarketScan Commercial database covering about one third of the US population <65 years during 2001–2009, and Medicare Supplemental data covering about one fifth of US seniors 65+ during 2006–2009. We extracted weekly time series of visits due to respiratory diagnoses, otitis media (OM), and urinary tract infections (UTI), a “negative control”. We used multiple linear regression modelling to estimate age-specific influenza-related excess in office visits.

Results

In the <65 year age group, in the 8 pre-pandemic seasons studied and for the broadest defined respiratory outcome, the model attributed an average of ~14.5 M (Standard deviation [SD] across seasons 3.9 million) office visits to influenza (rate of 5,581/100,000 population). Of these, ~80 % of visits occurred in the 5–17 and 18–49 age group. In school children aged 5–17 year olds and adult 18–64 year age groups the majority of visits were due to influenza B, while A/H3N2 explained most visits in children <5 year olds. The model further attributed ~2.2 M OM visits (SD across seasons 790,000) annually to influenza, of which 86 % of these occurred in children <18 years; this indicates that 6.4 % of all infants <2 years and 4.9 % of all toddlers aged 2–4 years in the US have an influenza-attributable outpatient visit with an OM diagnosis. In seniors 65 years and older, our model attributed ~0.7 M (SD across seasons 351,000) respiratory visits to influenza (rate of 1,887/100,000 population). The model identified no significant excess UTI (negative control) visits in most seasons.

Conclusions

This is to our knowledge a first study of the outpatient burden of influenza in the US in a large database. The model estimated that 10 % of all children <18 years and 4 % of the entire population <65 years seek outpatient care for respiratory illness attributable to influenza annually.

Trial registration

ClinicalTrial.gov, NCT02019732.

Burden of influenza in Germany: a retrospective claims database analysis for the influenza season 2012/2013

OBJECTIVE

Seasonal influenza occurs in annual epidemics. The virus can cause severe illness and concomitant diseases with the highest risk for children, the elderly, and individuals with disease dispositions. The study objective is to assess the influenza burden in Germany.

METHODS

This retrospective claims data analysis used the Health Risk Institute research database containing anonymized data of 4 million individuals. The study period comprised the influenza season 2012/2013 in which patients with documented influenza were identified. Disease frequency rates were calculated for a population with disease dispositions and a population not at high risk. Disease burden was assessed based on health-services utilization during the influenza season. Vaccine rates were calculated by identifying vaccinations.

RESULTS

We observed 65,826 patients with influenza, resulting in 1,160,646 documented influenza cases after extrapolation. Overall, otitis media and pneumonia was higher in the influenza-infected population compared to the non-influenza-infected population and especially high in children. Hospitalization cost amounted to €87,202,485 with a mean stay of 7 days, and total outpatient costs were €14,947,976. Vaccination rates were <4 % for children and 37 % for patients aged >60.

CONCLUSIONS

Seasonal influenza can cause severe outcomes with hospitalizations and excess costs. Especially influenza-infected children are affected by concomitant diseases with higher disease burden. Furthermore, documented vaccination rates are quite low.

Detection of enterovirus D68 in patients hospitalised in three tertiary university hospitals in Germany, 2013 to 2014

Enterovirus D68 (EV-D68) has been recognised as a worldwide emerging pathogen associated with severe respiratory symptoms since 2009. We here report EV-D68 detection in hospitalised patients with acute respiratory infection admitted to three tertiary hospitals in Germany between January 2013 and December 2014. From a total of 14,838 respiratory samples obtained during the study period, 246 (1.7%) tested enterovirus-positive and, among these, 39 (15.9%) were identified as EV-D68. Infection was observed in children and teenagers (0–19 years; n=31), the majority (n=22) being under five years-old, as well as in adults > 50 years of age (n=8). No significant difference in prevalence was observed between the 2013 and 2014 seasons. Phylogenetic analyses based on viral protein 1 (VP1) sequences showed co-circulation of different EV-D68 lineages in Germany. Sequence data encompassing the entire capsid region of the genome were analysed to gain information on amino acid changes possibly relevant for immunogenicity and revealed mutations in two recently described pleconaril binding sites.

Seasonal variation of diseases in children: a 6-year prospective cohort study in a general hospital

Seasonal variation in pediatrics has been well described in some infectious diseases, asthma, and diabetes, but data on seasonality for other diseases in children are sparse. To explore the extent of seasonal variation of the entire pediatric field, we analyzed diagnostic codes of all newly referred patients (n = 51,054) to our pediatric department of a large teaching hospital in the Netherlands over a 6-year period (2008-2013). Seasonality was analyzed using simple moving averages, the standard error of the mean (SEM) and the percentage monthly variation. We defined seasonal variation as a visually recognizable periodic pattern in every year in combination with a standard error of the mean > 0.20. Four diseases fulfilled our definition of seasonality: respiratory tract infections (peak in January, +107.0 %), gastroenteritis (peak in February-March, +95.8 % and +112.9 %, respectively), functional complaints (peak in March, +34.0 %, and November, +13.4 %), and asthma (peak in March, +27.8 %, and October, +17.5 %). Together, these four categories comprised 21.2 % of all newly referred patients.

CONCLUSION

Seasonal variation occurs in more than one fifth of all patients with pediatric disease. We demonstrated not only seasonal variation for respiratory tract infections, gastroenteritis, and asthma, but also for functional complaints.

WHAT IS KNOWN

• Seasonal variation has been described for pediatric diseases such as bronchiolitis, gastroenteritis, asthma, and diabetes. • Information on seasonality in other pediatric fields is sparse but may be helpful in understanding pathophysiology and workforce planning. What is new: • This study confirmed seasonal variation in respiratory infection diseases gastroenteritis and asthma. • Moreover, it showed seasonal variation for functional complaints for example (abdominal pain and headache), which has not been described previously.

Preterm Birth during Influenza Season Is Associated with Adverse Outcome in Very Low Birth Weight Infants

OBJECTIVE

We investigated the relationship between influenza seasonality and outcome of very low birth weight infants (VLBWI) in a large observational cohort study of the German Neonatal Network.

MATERIALS AND METHODS

Within the observational period (July 2009 until December 2014), five influenza seasons occurred (mean duration: 97 days, range: 48-131 days). We stratified VLBWI (n = 10,187) according to date of birth into three categories: (1) before influenza season, (2) during influenza season, and (3) 3 months after the end of the respective season. Outcomes were assessed in univariate and logistic regression analyses. In a subgroup of infants (n = 1497), the number of respiratory infections during the first 24 months of life was assessed.

RESULTS

VLBWI born during influenza season carried a higher risk for clinical sepsis (31.0 vs. 28.2%; p = 0.014) and periventricular leukomalacia (PVL, 3.7 vs. 2.5%, p = 0.004). In a multivariate logistic regression model, birth during influenza season was associated with PVL [odds ratio (OR) 1.47 (1.11-1.95), p = 0.007] and clinical sepsis [OR 1.13 (1.01-1.27), p = 0.036], independent of known risk factors, i.e., gestational age, multiple birth, gender, and small for gestational age. The risk for bronchopulmonary dysplasia was not influenced by influenza seasonality. In the small subgroup with information on 24 months follow-up (n = 1497), an increased incidence of common cold and bronchitis episodes was noted in infants born during influenza season.

CONCLUSION

Our observational data indicate that preterm birth during influenza season is associated with PVL and sepsis. These are novel aspects that deserve further investigations to address underlying causes and to include virus surveillance.

Clinical Endpoints for Respiratory Syncytial Virus Prophylaxis Trials in Infants and Children in High-income and Middle-income Countries

Respiratory syncytial virus (RSV) continues to cause significant clinical and economic burden around the world. Historically, RSV-associated hospitalization was used as a primary endpoint for RSV prophylaxis trials in infants. However, because of the changing epidemiology and healthcare system landscape, this endpoint has become a critical bottleneck on the pathway to licensure for new therapeutics. A panel of 7 RSV experts was convened (Chicago, IL, May 22, 2014) to evaluate the challenges of defining RSV prevention endpoints for clinical trials and to develop endpoints that are clinically meaningful while minimizing subjectivity and bias to achieve sufficient consistency of response for regulatory approval. Particular consideration was given to the ability to collect data systematically and consistently in countries with different healthcare practices and systems, while capturing the greatest proportion of disease impact. The group consensus was that a clinically meaningful primary endpoint could include medically attended RSV illness in settings beyond RSV-associated hospitalizations alone, in particular, a composite reduction in hospitalization, emergency room or urgent care center visits because of an RSV respiratory infection. Relevant secondary endpoints included reductions in RSV lower respiratory tract infection, RSV-related intensive care unit rates, subsequent recurrent wheezing or asthma and direct and indirect costs.

Associations between Meteorological Parameters and Influenza Activity in Berlin (Germany), Ljubljana (Slovenia), Castile and León (Spain) and Israeli Districts

BACKGROUND

Studies in the literature have indicated that the timing of seasonal influenza epidemic varies across latitude, suggesting the involvement of meteorological and environmental conditions in the transmission of influenza. In this study, we investigated the link between meteorological parameters and influenza activity in 9 sub-national areas with temperate and subtropical climates: Berlin (Germany), Ljubljana (Slovenia), Castile and León (Spain) and all 6 districts in Israel.

METHODS

We estimated weekly influenza-associated influenza-like-illness (ILI) or Acute Respiratory Infection (ARI) incidence to represent influenza activity using data from each country's sentinel surveillance during 2000-2011 (Spain) and 2006-2011 (all others). Meteorological data was obtained from ground stations, satellite and assimilated data. Two generalized additive models (GAM) were developed, with one using specific humidity as a covariate and another using minimum temperature. Precipitation and solar radiation were included as additional covariates in both models. The models were adjusted for previous weeks' influenza activity, and were trained separately for each study location.

RESULTS

Influenza activity was inversely associated (p<0.05) with specific humidity in all locations. Minimum temperature was inversely associated with influenza in all 3 temperate locations, but not in all subtropical locations. Inverse associations between influenza and solar radiation were found in most locations. Associations with precipitation were location-dependent and inconclusive. We used the models to estimate influenza activity a week ahead for the 2010/2011 period which was not used in training the models. With exception of Ljubljana and Israel's Haifa District, the models could closely follow the observed data especially during the start and the end of epidemic period. In these locations, correlation coefficients between the observed and estimated ranged between 0.55 to 0.91and the model-estimated influenza peaks were within 3 weeks from the observations.

CONCLUSION

Our study demonstrated the significant link between specific humidity and influenza activity across temperate and subtropical climates, and that inclusion of meteorological parameters in the surveillance system may further our understanding of influenza transmission patterns.

Cost for physician-diagnosed influenza and influenza-like illnesses on primary care level in Germany--results of a database analysis from May 2010 to April 2012

BACKGROUND

Seasonal influenza is one of the most significant infectious diseases in Germany; epidemic outbreaks occur every winter and cause substantial morbidity and mortality. However, published data from Germany on the current economic burden of influenza and the costs per episode are lacking.

METHODS

A retrospective database analysis was conducted using a longitudinal electronic medical records database (IMS Disease Analyzer). Patients with influenza, diagnosed by German office-based physicians using ICD-10 J09-11 (International Classification of Diseases, 10(th) revision), who were observable in the database from 12 months before the index (diagnosis) date until 1 month afterwards, were included. The selection window, defined to cover two influenza seasons, was May 2010 to April 2012. Direct and indirect costs were evaluated from payer, patient and societal perspectives. Published unit costs and tariffs from Germany (2012) were used for the analysis.

RESULTS

A total of 21,039 influenza-attributable episodes in 17,836 adults, managed by primary care physicians (PCP) and 7,107 episodes in 6,288 children, managed by pediatricians, were eligible for analysis. The mean (±Standard Deviation (SD)) age of the adults with at least one episode was 46 (±18) years and 7 (±4) years in the children. The presence of clinical risk factors was documented for 39% episodes in adults and 24% episodes in children, with the most common being cardiovascular diseases in adults (29%) and chronic respiratory diseases in children (23%). Complications and severe symptoms accompanied the influenza-attributable episode (adults: 37%, children: 54%), bronchitis (adults: 16%, children: 19%) and acute upper respiratory infection (adults: 15%, children: 21%) being the most frequent. From a societal perspective, the total average mean cost (±SD) per episode was €514 (±609) in adults, where work days lost were the main cost driver (82%), and €105 (±224) in children. Complications and severe symptoms increased the cost per episode versus episodes without by 1.7 times in adults (€684 (±713) vs. €413 (±510)) and nearly 3 times in children (€149 (±278) vs. €55 (±116)).

CONCLUSIONS

Based on a large patient sample derived from representative PCP and pediatricians panels, our results demonstrate that seasonal influenza is associated with substantial clinical and economic burden in Germany.

Protection against Influenza A Virus Challenge with M2e-Displaying Filamentous Escherichia coli Phages

Human influenza viruses are responsible for annual epidemics and occasional pandemics that cause severe illness and mortality in all age groups worldwide. Matrix protein 2 (M2) of influenza A virus is a tetrameric type III membrane protein that functions as a proton-selective channel. The extracellular domain of M2 (M2e) is conserved in human and avian influenza A viruses and is being pursued as a component for a universal influenza A vaccine. To develop a M2e vaccine that is economical and easy to purify, we genetically fused M2e amino acids 2-16 to the N-terminus of pVIII, the major coat protein of filamentous bacteriophage f88. We show that the resulting recombinant f88-M2e2-16 phages are replication competent and display the introduced part of M2e on the phage surface. Immunization of mice with purified f88-M2e2-16 phages in the presence of incomplete Freund's adjuvant, induced robust M2e-specific serum IgG and protected BALB/c mice against challenge with human and avian influenza A viruses. Thus, replication competent filamentous bacteriophages can be used as efficient and economical carriers to display conserved B cell epitopes of influenza A.

Using an adjusted Serfling regression model to improve the early warning at the arrival of peak timing of influenza in Beijing

Serfling-type periodic regression models have been widely used to identify and analyse epidemic of influenza. In these approaches, the baseline is traditionally determined using cleaned historical non-epidemic data. However, we found that the previous exclusion of epidemic seasons was empirical, since year-year variations in the seasonal pattern of activity had been ignored. Therefore, excluding fixed ‘epidemic’ months did not seem reasonable. We made some adjustments in the rule of epidemic-period removal to avoid potentially subjective definition of the start and end of epidemic periods. We fitted the baseline iteratively. Firstly, we established a Serfling regression model based on the actual observations without any removals. After that, instead of manually excluding a predefined ‘epidemic’ period (the traditional method), we excluded observations which exceeded a calculated boundary. We then established Serfling regression once more using the cleaned data and excluded observations which exceeded a calculated boundary. We repeated this process until the R² value stopped to increase. In addition, the definitions of the onset of influenza epidemic were heterogeneous, which might make it impossible to accurately evaluate the performance of alternative approaches. We then used this modified model to detect the peak timing of influenza instead of the onset of epidemic and compared this model with traditional Serfling models using observed weekly case counts of influenza-like illness (ILIs), in terms of sensitivity, specificity and lead time. A better performance was observed. In summary, we provide an adjusted Serfling model which may have improved performance over traditional models in early warning at arrival of peak timing of influenza.

Internet-based syndromic monitoring of acute respiratory illness in the general population of Germany, weeks 35/2011 to 34/2012

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