Syndromic Surveillance for Local Outbreaks of Lower-Respiratory Infections: Would It Work?

Background: Although syndromic surveillance is increasingly used to detect unusual illness, there is a debate whether it is useful for detecting local outbreaks. We evaluated whether syndromic surveillance detects local outbreaks of lower-respiratory infections (LRIs) without swamping true signals by false alarms. Methods and Findings: Using retrospective hospitalization data, we simulated prospective surveillance for LRI-elevations. Between 1999–2006, a total of 290762 LRIs were included by date of hospitalization and patients place of residence (>80% coverage, 16 million population). Two large outbreaks of Legionnaires disease in the Netherlands were used as positive controls to test whether these outbreaks could have been detected as local LRI elevations. We used a space-time permutation scan statistic to detect LRI clusters. We evaluated how many LRI-clusters were detected in 1999–2006 and assessed likely causes for the cluster-signals by looking for significantly higher proportions of specific hospital discharge diagnoses (e.g. Legionnaires disease) and overlap with regional influenza elevations. We also evaluated whether the number of space-time signals can be reduced by restricting the scan statistic in space or time. In 1999–2006 the scan-statistic detected 35 local LRI clusters, representing on average 5 clusters per year. The known Legionnaires' disease outbreaks in 1999 and 2006 were detected as LRI-clusters, since cluster-signals were generated with an increased proportion of Legionnaires disease patients (p:<0.0001). 21 other clusters coincided with local influenza and/or respiratory syncytial virus activity, and 1 cluster appeared to be a data artifact. For 11 clusters no likely cause was defined, some possibly representing as yet undetected LRI-outbreaks. With restrictions on time and spatial windows the scan statistic still detected the Legionnaires' disease outbreaks, without loss of timeliness and with less signals generated in time (up to 42% decline). Conclusions: To our knowledge this is the first study that systematically evaluates the performance of space-time syndromic surveillance with nationwide high coverage data over a longer period. The results show that syndromic surveillance can detect local LRI-outbreaks in a timely manner, independent of laboratory-based outbreak detection. Furthermore, since comparatively few new clusters per year were observed that would prompt investigation, syndromic hospital-surveillance could be a valuable tool for detection of local LRI-outbreaks. (aut. ref.

Limited effect of highly active antiretroviral therapy among HIV-positive injecting drug users on the population level

There is evidence that HIV-positive injecting drug users benefit less than other risk groups from highly active antiretroviral therapy that has been available since 1996. In this multicentre European study the impact of the availability of highly active antiretroviral therapy on the progression rates to AIDS and death among injecting drug users with a documented date of HIV seroconversion is studied. After highly active antiretroviral therapy became available the risk of AIDS and death for injecting drug users decreased by 28% and 36%, which is less than has been reported for other risk group

Association between work sick-leave absenteeism and SARS-CoV-2 notifications in the Netherlands during the COVID-19 epidemic

Background: Alternative data sources for surveillance have gained importance in maintaining coronavirus disease 2019 (COVID-19) situational awareness as nationwide testing has drastically decreased. Therefore, we explored whether rates of sick-leave from work are associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) notification trends and at which lag, to indicate the usefulness of sick-leave data for COVID-19 surveillance. Methods: We explored trends during the COVID-19 epidemic of weekly sick-leave rates and SARS-CoV-2 notification rates from 1 June 2020 to 10 April 2022. Separate time series were inspected visually. Then, Spearman correlation coefficients were calculated at different lag and lead times of zero to four weeks between sick-leave and SARS-CoV-2 notification rates. We distinguished between four SARS-CoV-2 variant periods, two labour sectors and overall, and all-cause sick-leave versus COVID-19-specific sick-leave. Results: The correlation coefficients between weekly all-cause sick-leave and SARS-CoV-2 notification rate at optimal lags were between 0.58 and 0.93, varying by the variant period and sector (overall: 0.83, lag −1; 95% CI [0.76, 0.88]). COVID-19-specific sick-leave correlations were higher than all-cause sick-leave correlations. Correlations were slightly lower in healthcare and education than overall. The highest correlations were mostly at lag −2 and −1 for all-cause sick-leave, meaning that sick-leave preceded SARS-CoV-2 notifications. Correlations were highest mostly at lag zero for COVID-19-specific sick-leave (coinciding with SARS-CoV-2 notifications). Conclusion: All-cause sick-leave might offer an earlier indication and evolution of trends in SARS-CoV-2 rates, especially when testing is less available. Sick-leave data may complement COVID-19 and other infectious disease surveillance systems as a syndromic data source

Spread of Hepatitis C Virus among European Injection Drug Users Infected with HIV: A Phylogenetic Analysis

To describe the spread of hepatitis C virus (HCV) among HCV/human immunodeficiency virus (HIV)-coinfected injection drug users (IDUs), the molecular epidemiology of HCV was studied among 108 IDUs from 7 European countries. Phylogenetic analysis based on the NS5B region showed great sequence variation of HCV within each country and no clear phylogenetic clustering by geographic region. The most prevalent subtypes were 1a and 3a, but the percentage of genotype 4 was also relatively high, ranging from 7% in northern Europe to 24% in southern Europe. Genotype 4 consisted mainly of subtype 4d and has entered the majority of the IDU populations studied. The significantly lower evolutionary distances within subtype 4d suggest that this subtype may have entered the European IDU population relatively recently. In conclusion, HCV exchange between European IDU populations has occurred on a large scale, and, overall, country-specific clustering for HCV was less than that shown for HI

Validation of Syndromic Surveillance for Respiratory Pathogen Activity

The studied respiratory syndromes are suitable for syndromic surveillance because they reflect respiratory pathogen activity pattern

Comparing Pandemic to Seasonal Influenza Mortality: Moderate Impact Overall but High Mortality in Young Children

Background: We assessed the severity of the 2009 influenza pandemic by comparing pandemic mortality to seasonal influenza mortality. However, reported pandemic deaths were laboratory-confirmed - and thus an underestimation - whereas seasonal influenza mortality is often more inclusively estimated. For a valid comparison, our study used the same statistical methodology and data types to estimate pandemic and seasonal influenza mortality. Methods and Findings: We used data on all-cause mortality (1999-2010, 100% coverage, 16.5 million Dutch population) and influenza-like-illness (ILI) incidence (0.8% coverage). Data was aggregated by week and age category. Using generalized estimating equation regression models, we attributed mortality to influenza by associating mortality with ILI-incidence, while adjusting for annual shifts in association. We also adjusted for respiratory syncytial virus, hot/cold weather, other seasonal factors and autocorrelation. For the 2009 pandemic season, we estimated 612 (range 266-958) influenza-attributed deaths; for seasonal influen

Real-time monitoring shows substantial excess all-cause mortality during second wave of COVID-19 in Europe, October to December 2020.

The European monitoring of excess mortality for public health action (EuroMOMO) network monitors weekly excess all-cause mortality in 27 European countries or subnational areas. During the first wave of the coronavirus disease (COVID-19) pandemic in Europe in spring 2020, several countries experienced extraordinarily high levels of excess mortality. Europe is currently seeing another upsurge in COVID-19 cases, and EuroMOMO is again witnessing a substantial excess all-cause mortality attributable to COVID-19.Funding statement: The EuroMOMO network hub at Statens Serum Institut receives funding from European Centre for Disease Prevention and Control, Solna, Sweden, through a framework contract 2017-2020.S

Infection with concurrent multiple hepatitis C virus genotypes is associated with faster HIV disease progression

OBJECTIVE: To elucidate the importance of hepatitis C Virus (HCV) genotype in HIV disease progression. DESIGN: This study was conducted among 126 HIV/HCV co-infected drug users with a known interval of HIV seroconversion whose HCV genotype was known early in HIV infection. Both clinical progression (to AIDS) and immunological progression (to a CD4+ T-cell count of 200 x 10(6) cells/l) by HCV genotype were studied using Cox proportional hazards analysis. RESULTS: The median duration of follow-up was 7.3 years [interquartile range (IQR), 4.6-10.1 years]. The majority of the HCV infections concerned genotype 1 and genotype 3; The distribution was: HCV type 1: 48%, HCV type 3: 34%, HCV type 4: 13%, multiple HCV types: 5%. Concurrent multiple infections consisted of HCV genotypes 1b+3a, 1b+4 and 3a+4. HCV genotype 1 and multiple HCV genotype infections were associated with faster immunological progression [hazard ratio (HR), 2.02; 95% confidence interval (CI), 1.04-3.92 and HR, 2.74; 95% CI, 0.95-7.90, respectively]. Multiple HCV genotype infection was also associated with faster clinical progression (HR, 3.36; 95% CI, 0.82-13.79). These hazard ratios increased further and were all significant when analyses were limited to data in the pre-HAART era (HR, 3.92; 95% CI, 1.51-10.20; HR, 4.38; 95% CI, 1.04-18.40 and HR, 6.54; 95% CI, 1.39-30.76, respectively). CONCLUSION: HIV disease progression differs by HCV genotype and is especially faster in individuals whose HCV infection involves more than one HCV genotype. The effect of HCV genotype on HIV progression was greater in the pre-highly active antiretroviral therapy (HAART) era, suggesting that the effectiveness of HAART may diminish the effect of HCV genotype on HIV disease progressio