Effect of portable HEPA filters on COVID-19 period prevalence: an observational quasi-interventional study in German kindergartens.

OBJECTIVES: The aim of the study was to evaluate the effect of high-efficiency particulate air (HEPA) filters on COVID-19 period prevalence in kindergartens. DESIGN: The observational study follows an intervention design with the intervention group using HEPA filters and the control group not. SETTING: The study was conducted in 32 (10 intervention, 22 control) kindergartens (daycare centres) in Rhineland Palatinate (Germany). PARTICIPANTS: Data of 2360 children (663 intervention, 1697 control) were reported by the kindergarten heads. Data were collected on institutional level without any identifying information on individuals. Thus, all children of all facilities were included; however, no demographic data were recorded. INTERVENTIONS: The study followed a quasi-interventional design, as no formal intervention was conducted. A charity foundation equipped kindergartens with HEPA filters. These kindergartens were enrolled as intervention group. The control group was recruited from the neighbouring communities and districts. OUTCOME MEASURES: The primary outcome measure was the number of COVID-19 cases reported by the kindergarten heads, converted into period prevalence rates per 1000 population. RESULTS: The mean COVID-19 period prevalence rates of the control and intervention groups were 186 (95% CI: 137.8 to 238.9) and 372 (95% CI: 226.6 to 517.6) per 1000 children, respectively. The one-sided Wilcoxon rank-sum test indicates a p value of 0.989; thus, the hypothesised preventive effect of HEPA filters could not be confirmed in the kindergarten setting. CONCLUSIONS: While HEPA filters can significantly reduce the viral load in room air, this does not lead to reduced COVID-19 prevalence in the selected kindergartens in Germany. It is known that contagion mainly occurs via direct face-to-face air exchange during play and that the contaminated air does not necessarily pass through the filter prior to air exchange between children. The use of HEPA filters may also lead to a sense of security, leading to reduced preventive behaviour.

Legionella in drinking water: the detection method matters.

Legionella concentrations in drinking water have been regulated for decades and are evaluated with regard to their concentrations in drinking water plumbing systems (DWPS). The respective action levels differ at the international level. In Germany, the Federal Environment Agency (UBA) specifies the application of ISO 11731 for the detection of legionella in drinking water and gives a binding recommendation for the methods to be used for culturing and evaluation. Effective from 01 March 2019, the UBA recommendation was revised. The utilized culture media in the culture approach were altered, consequently affecting the spectrum of legionella colonies detected in drinking water. Using data from a routine legionella monitoring of a large laboratory, over a period of 6 years and 17,270 individual drinking water samples, allowed us to assess the impact of the alteration on the assessment of DWPS. By comparing the amount of action level exceedances before and after the method change, it could be demonstrated that exceedances are reported significantly more often under the new method. Consequently, the corresponding action level for evaluation of legionella contamination and the resulting risk to human health needs to be revised to avoid the misleading impression of increased health risk.

Burden of hospital admissions and resulting patient interhospital transports during the 2020/2021 SARS-CoV-2 pandemic in Saxony, Germany.

Secondary transports of patients from one hospital to another are indicated for medical reasons or to address local constraints in capacity. In particular, interhospital transports of critically ill infectious patients present a logistical challenge and can be key in the effective management of pandemic situations. The state of Saxony in Germany has two characteristics that allow for an extensive evaluation of secondary transports in the pandemic year 2020/2021. First, all secondary transports are centrally coordinated by a single institution. Second, Saxony had the highest SARS-CoV-2 infection rates and the highest COVID-19 associated mortality in Germany. This study evaluates secondary interhospital transports from March 2019 to February 2021 in Saxony with a detailed analysis of transport behaviour during the pandemic phase March 2020 to February 2021. Our analysis includes secondary transports of SARS-CoV-2 patients and compares them to secondary transports of non-infectious patients. In addition, our data show differences in demographics, SARS-CoV-2- incidences, ICU occupancy of COVID-19 patients, and COVID-19 associated mortality in all three regional health clusters in Saxony. In total, 12,282 secondary transports were analysed between March 1st, 2020 and February 28th, 2021, of which 632 were associated with SARS-CoV-2 (5.1%) The total number of secondary transports changed slightly during the study period March 2020 to February 2021. Transport capacities for non-infectious patients were reduced due to in-hospital and out-of-hospital measures and could be used for transport of SARS-CoV-2 patients. Infectious transfers lasted longer despite shorter distance, occurred more frequently on weekends and transported patients were older. Primary transport vehicles were emergency ambulances, transport ambulances and intensive care transport vehicles. Data analysis based on hospital structures showed that secondary transports in correlation to weekly case numbers depend on the hospital type. Maximum care hospitals and specialized hospitals show a maximum of infectious transports approximately 4 weeks after the highest incidences. In contrast, standard care hospitals transfer their patients at the time of highest SARS-CoV-2 case numbers. Two incidence peaks were accompanied by two peaks of increased secondary transport. Our findings show that interhospital transfers of SARS-CoV-2 and non-SARS-CoV-2 patients differ and that different hospital care levels initiated secondary transports at different times during the pandemic.

Clinically relevant antibiotic-resistant bacteria in aquatic environments - An optimized culture-based approach.

The emergence of antibiotic-resistant clinically relevant facultative pathogenic bacteria in the environment has become one of the most important global health challenges. Antibiotic-resistant bacteria (ARB) have been found in surface waters and wastewater treatment plants. Drinking water guidelines and the EU bathing water directive 2006/7/EC include the surveillance of defined microbiological parameters on species level, while the monitoring of ARB is missing in all existing guidelines. However, standardized methods for the detection of ARB exist for clinical investigations of human materials only. They are based on cultivation on selective agar plates. These methods cannot be used directly for environmental samples, because of the high amount and diversity of bacterial background flora which interferes with the detection of human-relevant ARB. The aim of this study was to introduce a proposal for future normative standard operation procedures, with international relevance, for the culture-based detection of clinically-relevant antibiotic resistant bacteria in aquatic environmental samples like wastewater and surface water: gram-negative bacteria resistant against 3rd generation cephalosporins (ESBL) and against carbapenems (CARBA), gram-positive vancomycin-resistant enterococci (VRE) and methicillin-resistant Staphylococcus aureus (MRSA). The final adaptation of standardized cultivation methods included increasing the standard incubation temperature from 36 °C to 42 °C, which effectively inhibits the environmental background flora on agar plates while the desired target species survive. This enables the detection of target species in suitable sample volumes. Putative target colonies which belong to the remaining background flora had to be excluded by morphological and physiological differentiation. Therefore, a time and cost optimized testing scheme with good performance was developed, which allows an effective exclusion of non-target isolates in samples. Depending on the target species and sample type, sensitivity of up to 100% is achieved, and specificity ranges from 91.1% to 99.7%, while the positive predictive value, negative predicted value and accuracy rate are always >90%.