A survey of the representativeness and usefulness of wastewater-based surveillance systems in 10 countries across Europe in 2023.

Wastewater-based surveillance (WBS) has become a widespread method to monitor transmission of SARS-CoV-2 and other human pathogens in Europe. We conducted a survey about WBS systems' objectives, approaches, representativeness and usefulness in 10 invited European countries in 2023, i.e. Austria, Belgium, Denmark, Finland, Greece, Hungary, Italy, Luxembourg, the Netherlands and Norway. All countries completed the study questionnaire about their SARS-CoV-2 WBS systems, and shared information about WBS of other pathogens as deemed relevant. SARS-CoV-2 WBS systems primarily monitored national and subnational trends (population coverage: 25-99%), and a majority (8/10) also tracked variant distribution. Nine of 10 countries reported that their SARS-CoV-2 WBS systems were representative of their population and all countries remarked that the findings were valuable for public health decision-making. Results were shared with relevant public health authorities and published via dedicated websites and/or dashboards. WBS systems of other pathogens were mostly in the early stages, with some countries implementing pilots. Notable exceptions were the well-established poliovirus surveillance systems in Finland, Italy and the Netherlands. This study brings understanding the diverse landscape of WBS in Europe, offering insights for future developments and collaborations. Furthermore, it highlights the need for further integration of WBS into other European surveillance systems.

Determinants of Sporadic Shiga Toxin-Producing Escherichia coli (STEC) Infection in Denmark, 2018-2020: A Matched Case-Control Study.

Infections with Shiga toxin-producing Escherichia coli (STEC) are increasing in Denmark and elsewhere. STEC is also the most frequent cause of haemolytic uraemic syndrome (HUS) in Danish children. Most cases are considered sporadic, while approximately one-third can be attributed to a known source of infection. Hence, we examined sources of sporadic STEC infection in Denmark. From January 2018 to December 2020, we conducted a prospective nationwide case-control study among Danish adults and children. Cases with confirmed positive STEC infection were notified infections within the national laboratory surveillance system. Control persons were randomly selected from the Danish Civil Registration System, individually matched in age in 5-year bands and sex. Participants were invited by an electronic letter to complete either an adult or child questionnaire online. Univariate and adjusted matched odds ratios were computed for adults and children using conditional logistic regression. The study recruited 1583 STEC cases and 6228 controls. A total of 658 cases (42%) and 2155 controls (35%) were included in the analysis. Depending on age, univariate analysis adjusted for socio-demographic determinants showed that the consumption of boiled beef (mOR = 2.2, 95% confidence interval (CI): 1.6-3.1) and fried minced beef (mOR = 1.6, CI: 1.2-2.1), drinking raw (unpasteurized) milk (mOR = 11, CI 1.1-110), eating grilled food (mOR = 9.8, CI: 5.6-17) and having a household member using diapers (mOR = 2.1, CI: 1.4-3.2) were determinants of sporadic STEC infection. Further multivariate adjusted analysis resulted in the same determinants. This study confirms that beef is an overall important risk factor for STEC infection in Denmark. We also present evidence that a proportion of sporadic STEC infections in Denmark are determined by age-specific eating habits, environmental exposures and household structure, rather than being exclusively food-related. These findings are relevant for targeted public health actions and guidelines.

Automated local lockdowns for SARS-CoV-2 epidemic control-assessment of effect by controlled interrupted time series analysis.

Objectives: During the COVID-19 pandemic, broad non-pharmaceutical interventions such as national lockdowns were effective but had significant drawbacks, prompting targeted approaches, such as Denmark's localized lockdowns, based on specific epidemiological criteria. This study evaluates the effect of Denmark's automated local lockdown strategy on epidemic control to inform future response. Methods: This was a register-based controlled interrupted time series analysis, examining SARS-CoV-2 infection rates in Danish parishes from March to September 2021. The matching of control parishes was based on location, time, and pre-lockdown infection trends, with the lockdown's start defined as the day after a parish exceeded the lockdown criteria. Follow-up included 3-week pre-lockdown and 2-week post-lockdown. Results: A total of 30 parishes were mandated to lockdown, approximately 3.5% of the population of Denmark. A total of 94 control parishes were used as 109 controls. The decrease in the incidence during the 2-week follow-up period after the initiation of the lockdown was 13% points higher in case parishes: in case parishes, the incidence was reduced by 78% compared with 65% in control parishes. Conclusions: Our findings demonstrate that local lockdowns did have a positive effect in mitigating the spread of the SARS-CoV-2 virus, making them valuable in the fight against the COVID-19 pandemic and an important alternative to national lockdowns.

Cohort profile: EFTER-COVID - a Danish nationwide cohort for assessing the long-term health effects of the COVID-19 pandemic.

PURPOSE: To follow SARS-CoV-2-infected persons up to 18 months after a positive test in order to assess the burden and nature of post acute symptoms and health problems. PARTICIPANTS: Persons in Denmark above 15 years of age, who were tested positive for SARS-CoV-2 during 1 September 2020 to 21 February 2023 using a RT-PCR test. As a reference group, three test-negative individuals were selected for every two test-positive individuals by matching on test date. FINDINGS TO DATE: In total, 2 427 913 invitations to baseline questionnaires have been sent out and 839 528 baseline questionnaires (34.5%) have been completed. Females, the age group 50-69 years, Danish-born and persons, who had received at least one SARS-CoV-2 vaccination booster dose were more likely to participate. Follow-up questionnaires were sent at 2, 4, 6, 9, 12 and 18 months after the test, with response rates at 42%-54%. FUTURE PLANS: New participants have been recruited on a daily basis from 1 August 2021 to 23 March 2023. Data collection will continue until the last follow-up questionnaires (at 18 months after test) have been distributed in August 2024.

A register and questionnaire study of long-term general health symptoms following SARS-CoV-2 vaccination in Denmark.

Many individuals who refuse COVID-19 vaccination have concerns about long-term side effects. Here, we report findings on self-reported symptoms from a Danish survey- and register study. The study included 34,868 vaccinated primary course recipients, 95.8% of whom received mRNA vaccines, and 1,568 unvaccinated individuals. Participants had no known history of SARS-CoV-2 infection. Using g-computation on logistic regression, risk differences (RDs) for symptoms between vaccinated and unvaccinated persons were estimated with adjustments for possible confounders. Within six weeks after vaccination, higher risks were observed for physical exhaustion (RD 4.9%, 95% CI 1.1% to 8.4%), fever or chills (RD 4.4%, 95% CI 2.1% to 6.7%), and muscle/joint pain (RD 7.0%, 95% CI 3.1% to 10.7%), compared to unvaccinated individuals. Beyond twenty-six weeks, risks were higher among the vaccinated for sleeping problems (RD 3.0, 95% 0.2 to 5.8), fever or chills (RD 2.0, 95% CI 0.4 to 3.6), reduced/altered taste (RD 1.2, 95% CI 0.2 to 2.3) and shortness of breath (RD 2.6, 95% CI 0.9 to 4.0). However, when examining pre-omicron responses only, the difference for reduced/altered taste was significant. As expected, the risk of experiencing physical exhaustion, fever or chills, and muscle/joint pain was higher among persons who responded within six weeks of completing the primary course. No significant differences were observed for the 7-25-week period after vaccination. Associations for the period beyond 26 weeks must be interpreted with caution and in the context of undetected SARS-CoV-2 infection, wide confidence intervals, and multiple testing. Overall, we observe no concerning signs of long-term self-reported physical, cognitive, or fatigue symptoms after vaccination.

Results from the SARS-CoV-2 wastewater-based surveillance system in Denmark, July 2021 to June 2022.

The microbiological analysis of wastewater samples is increasingly used for the surveillance of SARS-CoV-2 globally. We described the setup process of the national SARS-CoV-2 wastewater-based surveillance system in Denmark, presented its main results during the first year of activities, from July 2021 to June 2022, and discussed their operational significance. The Danish SARS-CoV-2 wastewater-based surveillance system was designed to cover 85 % of the population in Denmark and it entailed taking three weekly samples from 230 sites. Samples were RT-qPCR tested for SARS-CoV-2 RNA, targeting the genetic markers N1, N2 and RdRp, and for two faecal indicators, Pepper Mild Mottle Virus and crAssphage. We calculated the weekly SARS-CoV-2 RNA concentration in the wastewater from each sampling site and monitored it in view of the results from individual testing, at the national and regional levels. We attempted to use wastewater results to identify potential local outbreaks, and we sequenced positive wastewater samples using Nanopore sequencing to monitor the circulation of viral variants in Denmark. The system reached its full implementation by October 2021 and covered up to 86.4 % of the Danish population. The system allowed for monitoring of the national and regional trends of SARS-CoV-2 infections in Denmark. However, the system contribution to the identification of potential local outbreaks was limited by the extensive information available from clinical testing. The sequencing of wastewater samples identified relevant variants of concern, in line with results from sequencing of human samples. Amidst the COVID-19 pandemic, Denmark implemented a nationwide SARS-CoV-2 wastewater-based surveillance system that integrated routine surveillance from individual testing. Today, while testing for COVID-19 at the community level has been discontinued, the system is on the frontline to monitor the occurrence and spread of SARS-CoV-2 in Denmark.

Multinational collaboration in solving a European Salmonella Braenderup outbreak linked to imported melons, 2021.

A genomic cluster of Salmonella Braenderup ST22, a serovar of Salmonella enterica subsp. enterica which causes symptoms of gastrointestinal illness, was notified by Danish authorities to the European Centre for Disease Prevention and Control (ECDC) on 3 May 2021. By 6 July 2021, S. Braenderup outbreak cases (n = 348) had been reported from 12 countries in the European Union/European Economic Area (EU/EEA) and the United Kingdom (UK), including 68 hospitalised cases. With support from affected EU/EEA countries, and in partnership with the European Food Safety Authority (EFSA), ECDC established an international outbreak investigation team to rapidly identify the source and prevent outbreak spread. Consumption information was shared with affected countries through a standard line list, revealing that 124 of 197 cases (63%) reported having eaten (any) melons within 7 days prior to disease onset. The speed and completeness of the investigation, which identified the outbreak vehicle as galia melons imported from Honduras in June 2021, was a direct result of extensive collaboration and information sharing between countries' national food safety and public health authorities. This article describes the outbreak and the benefits, successes, and challenges of multi-country collaboration for consideration in future large foodborne outbreaks across Europe.

The effect of changing diagnostic method from culture to PCR on the number of episodes of human campylobacteriosis in Denmark: a retrospective study (2015-2022).

IMPORTANCE: This study is important because it shows the potential epidemiological silence associated with the use of culture as the primary diagnostic method for the laboratory identification of human campylobacteriosis. Also, we show how polymerase chain reaction methods are associated with a systematic increase in the number of human campylobacteriosis episodes as reported by routine disease surveillance. These findings are operationally relevant and have public health implications because they tell how crucial it is to consider changes in diagnostic methods, e.g., in the epidemiological analysis of historical data and in the interpretation of future data in light of the past. We also believe that this study highlights how the synergy between microbiology and epidemiology is essential for disease surveillance.

Assessing household lifestyle exposures from consumer purchases, the My Purchases cohort.

Consumer purchase data (CPD) is a promising instrument to assess the impact of purchases on health, but is limited by the need for manual scanning, a lack of access to data from multiple retailers, and limited information on product data and health outcomes. Here we describe the My Purchases cohort, a web-app enabled, prospective collection of CPD, covering several large retail chains in Denmark, that enables linkage to health outcomes. The cohort included 459 participants as of July 03, 2023. Up to eight years of CPD have been collected, with 2,225,010 products purchased, comprising 223,440 unique products. We matched 88.5% of all products by product name or item number to one generic food database and three product databases. Combined, the databases enable analysis of key exposures such as nutrients, ingredients, or additives. We found that increasing the number of retailers that provide CPD for each consumer improved the stability of individual CPD profiles and when we compared kilojoule information from generic and specific product matches, we found a median modified relative difference of 0.23. Combined with extensive product databases and health outcomes, CPD could provide the basis for extensive investigations of how what we buy affects our health.

A Danish questionnaire study of acute symptoms of SARS-CoV-2 infection by variant, vaccination status, sex and age.

It is not well-described how the acute symptoms of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) differ by variant, vaccination, sex and age. A cross-sectional questionnaire study linked to national testing- and registry data was conducted among 148,874 SARS-CoV-2 first time reverse transcription polymerase chain reaction (RT-PCR) test-positive individuals and corresponding date-matched symptomatic test-negative controls. Major SARS-CoV-2 variants (Index/wild type, Alpha, Delta and Omicron) were defined using periods of predominance. Risk differences (RDs) were estimated for each of 21 predefined acute symptoms comparing: (1) test-positive and -negative individuals, by variant period, (2) vaccinated and unvaccinated test-positives, by variant period, (3) individuals tested positive during the Omicron and Delta periods, by vaccination status, and (4) vaccinated Omicron test-positive and -negative individuals, by age and sex. Compared to pre-Omicron, RDs between test-positive and test-negative individuals during the Omicron period were lower for most symptoms. RDs for altered sense of smell (dysosmia) and taste (dysgeusia) were highest for Delta (RD = 50.8 (49.4-52.0) and RD = 54.7 (53.4-56.0), respectively) and lowest for Omicron (RD = 12.8 (12.1-13.5) and RD = 11.8 (11.1-12.4), respectively). Across variants, vaccinated individuals reported fewer symptoms. During Omicron, females and 30-59 year-old participants reported more symptoms.

Post-acute symptoms 4 months after SARS-CoV-2 infection during the Omicron period: a nationwide Danish questionnaire study.

Post-acute symptoms are not uncommon after SARS-CoV-2 infection with pre-Omicron variants. How Omicron and COVID-19 booster vaccination influence the risk of post-acute symptoms is less clear. We analyzed data from the nationwide Danish questionnaire study EFTER-COVID comprising 44,553 individuals ≥15 years old, tested between July 2021 and January 2022, in order to evaluate the association of the Omicron variant and COVID-19 booster vaccination with post-acute symptoms and new-onset general health problems, four months after infection with SARS-CoV-2. Risk differences (RDs) were estimated by comparing Omicron -cases to controls, Omicron to Delta -cases, and Omicron vaccinated cases with three to -two doses, adjusted for age, sex, BMI, self-reported chronic diseases, Charlson comorbidity index, healthcare occupation, and vaccination status. Four months after testing for SARS-CoV-2 during the Omicron period, cases experienced substantial post-acute symptoms and new-onset health problems compared to controls; the largest RD was observed for memory issues (RD=7.2%, 95%CI: 6.4 to 8.1). However, risks were generally lower than in the Delta period, particularly for dysosmia (RD=-15.0%, 95%CI: -17.0 to -13.2) and dysgeusia (RD=-11.2%, 95%CI: -13.2 to -9.5). Booster vaccination was associated with fewer post-acute symptoms and new-onset health problems, four months after Omicron infection, compared to two COVID-19 vaccine doses.

A hybrid register and questionnaire study of Covid-19 and post-acute sick leave in Denmark.

Post-acute sick leave is an underexplored indicator of the societal burden of SARS-CoV-2. Here,  we report findings about self-reported sick leave and risk factors thereof from a hybrid survey and register study, which include 37,482 RT-PCR confirmed SARS-CoV-2 cases and 51,336 test-negative controls who were tested during the index- and alpha-dominant waves. We observe that an additional 33 individuals per 1000 took substantial sick leave following acute infection compared to persons with no known history of infection, where substantial sick leave is defined as >1 month of sick leave within the period 1-9 months after the RT-PCR test date. Being female, 50-65 years, or having certain pre-existing health conditions such as obesity, chronic lung diseases, and fibromyalgia each increase risk for taking substantial sick leave. Altogether, these results may help motivate improved diagnostic and treatment options for persons living with post-Covid conditions.

Factors associated with the formation of SARS-CoV-2 case-clusters in Danish schools: a nationwide register-based observational study.

A register-based retrospective observational study was conducted to describe SARS-CoV-2 cases and case-clusters in schoolchildren of Danish primary and lower secondary schools and identify which factors were associated with the occurrence of case-clusters in schools. The study period was the autumn school semester 2021. Clusters were defined as three or more cases in a school-class level within 14 days. Descriptive analysis was carried out and multivariable logistic regression analysis was performed to determine which factors were associated with case introductions (i.e., primary case) being linked to a cluster. More cases and clusters were identified in lower than in higher class levels. Out of 21,497 cases introduced into a school, 41.6% started a cluster. A higher assumed immunity level in a class level was significantly reducing the odds of a case introduction being linked to a cluster (e.g., assumed immunity of ≥80% vs <20%: OR: 0.28; 95%CI: 0.17-0.44). A previous infection (in the primary case) had a protective effect (OR: 0.58; 95%CI: 0.33-0.99). This study suggests that most cases appearing in schools did not induce clusters, but that once cluster occur sizes can be large. It further indicates that vaccination of children markedly reduces the risk of secondary infections.

Predicting COVID-19 Incidence Using Wastewater Surveillance Data, Denmark, October 2021-June 2022.

Analysis of wastewater is used in many settings for surveillance of SARS-CoV-2, but it remains unclear how well wastewater testing results reflect incidence. Denmark has had an extensive wastewater analysis system that conducts 3 weekly tests in ≈200 sites and has 85% population coverage; the country also offers free SARS-CoV-2 PCR tests to all residents. Using time series analysis for modeling, we found that wastewater data, combined with information on circulating variants and the number of human tests performed, closely fitted the incidence curve of persons testing positive. The results were consistent at a regional level and among a subpopulation of frequently tested healthcare personnel. We used wastewater analysis data to estimate incidence after testing was reduced to a minimum after March 2022. These results imply that data from a large-scale wastewater surveillance system can serve as a good proxy for COVID-19 incidence and for epidemic control.

Patterns of testing in the extensive Danish national SARS-CoV-2 test set-up.

BACKGROUND: The Danish national SARS-CoV-2 mass test system was among the most ambitious worldwide. We describe its set-up and analyse differences in patterns of testing per demography and time period in relation to the three waves of SARS-CoV-2 transmission in Denmark. METHODS: We included all reported PCR- and rapid antigen-tests performed between 27 February 2020 and 10 March 2022 among all residents aged 2 years or above. Descriptive statistics and Poisson regression models were used to analyse characteristics of individuals tested for SARS-CoV-2 using a national cohort study design. RESULTS: A total of 63.7 million PCR-tests and 60.0 million rapid antigen-tests were performed in the study period, testing 90.9% and 78.8% of the Danish population at least once by PCR or antigen, respectively. Female sex, younger age, Danish heritage and living in the capital area were all factors positively associated with the frequency of PCR-testing. The association between COVID-19 vaccination and PCR-testing changed from negative to positive over time. CONCLUSION: We provide details of the widely available, free-of-charge, national SARS-CoV-2 test system, which served to identify infected individuals, assist isolation of infectious individuals and contact tracing, and thereby mitigating the spread of SARS-CoV-2 in the Danish population. The test system was utilized by nearly the entire population at least once, and widely accepted across different demographic groups. However, demographic differences in the test uptake did exist and should be considered in order not to cause biases in studies related to SARS-CoV-2, e.g., studies of transmission and vaccine effectiveness.

Influence of vaccination on adverse health outcomes after SARS-CoV-2 infection among individuals with alcohol use disorder: a population-based study.

BACKGROUND AND AIMS: Alcohol use disorders (AUD) have not been included in the priority groups for early vaccine against SARS-CoV-2. We aimed to determine adverse outcomes after SARS-CoV-2 infection among individuals with AUD and how this is modified by vaccination. DESIGN, SETTING AND PARTICIPANTS: This was a registry-based cohort study carried out in Denmark, 27 February 2020 to 15 October 2021, comprising 2157 individuals with AUD and 237 541 without AUD who had had a polymerase chain reaction (PCR)-confirmed SARS-CoV-2 infection during the study period. MEASUREMENTS: The association of AUD with the absolute and relative risk of hospitalization, intensive care and 60-day mortality after SARS-CoV-2 infection and of all-cause mortality throughout the follow-up period were measured. Potential interactions with SARS-CoV-2 vaccination, education and sex were explored in stratified analyses and tested by including interaction terms and using likelihood ratio tests. FINDINGS: Individuals with AUD had an increased absolute and relative risk of adverse outcomes, including hospitalization [incidence rate ratio (IRR) = 1.72, 95% confidence interval (CI) = 1.51-1.95], intensive care (IRR = 1.47, 95% CI = 1.07-2.02) and 60-day mortality [mortality rate ratio (MRR) = 2.35, 95% CI = 1.94-2.85] compared with SARS-CoV-2-positive individuals without AUD. Irrespective of AUD, highest risks of these adverse health outcomes were observed for individuals not vaccinated against SARS-CoV-2 infection, for individuals of low educational level and in males. However, for all-cause mortality throughout the follow-up period, SARS-CoV-2 infection showed a lower relative mortality risk increase, whereas being unvaccinated showed a higher relative mortality risk increase, in individuals with AUD than in the reference population without AUD (P of interaction tests < 0.0001). CONCLUSIONS: Both alcohol use disorder and being unvaccinated for SARS-CoV-2 appear to be independent risk factors for adverse health outcomes following SARS-CoV-2 infection.

Catering of high-risk foods and potential of stored food menu data for timely outbreak investigations in healthcare facilities, Italy and Germany.

Healthcare-associated foodborne outbreaks (HA-FBOs) can cause significant morbidity and mortality, affecting particularly vulnerable hospital populations. Electronic records of food served in healthcare facilities (HCFs) could be useful for timely investigations of HA-FBOs. We explored the availability and usability of electronic food menu data to support investigations of HA-FBOs through a survey among 35 HCFs in Germany (n = 13) and in Italy (n = 22). Large variability was reported in the storage time of menu data (from no storage up to 10 years) and their formats, including paper, electronic (PDF, Word, Excel), or fully searchable databases (15/22 in Italian HCFs, 3/13 in German HCFs). Food products that may present a risk to vulnerable persons - including deli salads, raw/fermented sausage products, soft cheese, smoked fish or frozen berries - were offered on the menu of all HCFs in Germany, and one-third of the Italian HCFs. The usability of electronic food menu data for the prevention or investigation of HA-FBOs may be suboptimal in a large number of HCFs in Germany, as well as in some HCFs in Italy. Standardised collection for use of electronic food menu data might help discover the association between illnesses and food eaten during outbreak investigations. Hospital hygienists, food safety and public health authorities should collaborate to increase implementation of food safety guidelines.

The incidence of laboratory-confirmed cases of enteric pathogens in Denmark 2018: a national observational study.

BACKGROUND: Only a subset of enteric pathogens is under surveillance in Denmark, and knowledge on the remaining pathogens detected in acute gastroenteritis is limited. Here, we present the one-year incidence of all enteric pathogens diagnosed in Denmark, a high-income country, in 2018 and an overview of diagnostic methods used for detection. METHODS: All 10 departments of clinical microbiology completed a questionnaire on test methods and provided 2018-data of persons with positive stool samples with Salmonella species, Campylobacter jejuni/coli, Yersinia enterocolitica, Aeromonas species, diarrheagenic Escherichia coli (Enteroinvasive (EIEC), Shiga toxin-producing (STEC), Enterotoxigenic (ETEC), Enteropathogenic (EPEC), and intimin-producing/attaching and effacing (AEEC)), Shigella species., Vibrio cholerae, norovirus, rotavirus, sapovirus, adenovirus, Giardia intestinalis, Cryptosporidium species, and Entamoeba histolytica. RESULTS: Enteric bacterial infections were diagnosed with an incidence of 229.9 cases/100,000 inhabitants, virus had an incidence of 86/100,000 and enteropathogenic parasites of 12.5/100,000. Viruses constituted more than half of diagnosed enteropathogens for children below 2 years and elderly above 80 years. Diagnostic methods and algorithms differed across the country and in general PCR testing resulted in higher incidences compared to culture (bacteria), antigen-test (viruses), or microscopy (parasites) for most pathogens. CONCLUSIONS: In Denmark, the majority of detected infections are bacterial with viral agents primarily detected in the extremes of ages and with few intestinal protozoal infections. Incidence rates were affected by age, clinical setting and local test methods with PCR leading to increased detection rates. The latter needs to be taken into account when interpreting epidemiological data across the country.

Early detection of local SARS-CoV-2 outbreaks by wastewater surveillance: a feasibility study.

Wastewater surveillance and quantitative analysis of SARS-CoV-2 RNA are increasingly used to monitor the spread of COVID-19 in the community. We studied the feasibility of applying the surveillance data for early detection of local outbreaks. A Monte Carlo simulation model was constructed, applying data on reported variation in RNA gene copy concentration in faeces and faecal masses shed. It showed that, even with a constant number of SARS-CoV-2 RNA shedders, the variation in concentrations found in wastewater samples will be large, and that it will be challenging to translate viral concentrations into incidence estimates, especially when the number of shedders is low. Potential signals for early detection of hypothetical outbreaks were analysed for their performance in terms of sensitivity and specificity of the signals. The results suggest that a sudden increase in incidence is not easily identified on the basis of wastewater surveillance data, especially in small sampling areas and in low-incidence situations. However, with a high number of shedders and when combining data from multiple consecutive tests, the performance of wastewater sampling is expected to improve considerably. The developed modelling approach can increase our understanding of the results from wastewater surveillance of SARS-CoV-2.

Correlation of High Seawater Temperature with Vibrio and Shewanella Infections, Denmark, 2010-2018.

During 2010-2018 in Denmark, 638 patients had Vibrio infections diagnosed and 521 patients had Shewanella infections diagnosed. Most cases occurred in years with high seawater temperatures. The substantial increase in those infections, with some causing septicemia, calls for clinical awareness and mandatory notification policies.