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Jonker L, Linde KJ, de Boer AR, Ding E, Zhang D, de Hoog MLA, Herfst S, Heederik DJJ, Fraaij PLA, Bluyssen PM, Wouters IM, Bruijning-Verhagen PCJL. SARS-CoV-2 incidence in secondary schools; the role of national and school-initiated COVID-19 measures. BMC Public Health 2023; 23:1243. [PMID: 37370045 DOI: 10.1186/s12889-023-16146-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 06/16/2023] [Indexed: 06/29/2023] Open
Abstract
INTRODUCTION Our aim was to gain insight into the effect of COVID-19 measures on SARS-CoV-2 incidence in secondary schools and the association with classroom CO2 concentration and airborne contamination. METHODS Between October 2020-June 2021, 18 schools weekly reported SARS-CoV-2 incidence and completed surveys on school-initiated COVID-19 measures (e.g. improving hygiene or minimizing contacts). CO2 was measured in occupied classrooms twice, and SARS-CoV-2 air contamination longitudinally using electrostatic dust collectors (EDC) and analyzed using RT-qPCR. National COVID-19 policy measures varied during pre-lockdown, lockdown and post-lockdown periods. During the entire study, schools were recommended to improve ventilation. SARS-CoV-2 incidence rate ratios (IRR) were estimated by Generalized Estimating Equation (GEE) models. RESULTS During 18 weeks follow-up (range: 10-22) SARS-CoV-2 school-incidence decreased during national lockdown (adjusted IRR: 0.41, 95%CI: 0.21-0.80) and post-lockdown (IRR: 0.60, 0.39-0.93) compared to pre-lockdown. School-initiated COVID-19 measures had no additional effect. Pre-lockdown, IRRs per 10% increase in time CO2 exceeded 400, 550 and 800 ppm above outdoor level respectively, were 1.08 (1.00-1.16), 1.10 (1.02-1.19), and 1.08 (0.95-1.22). Post-lockdown, CO2-concentrations were considerably lower and not associated with SARS-CoV-2 incidence. No SARS-CoV-2 RNA was detected in any of the EDC samples. CONCLUSION During a period with low SARS-CoV-2 population immunity and increased attention to ventilation, with CO2 levels most of the time below acceptable thresholds, only the national policy during and post-lockdown of reduced class-occupancy, stringent quarantine, and contact testing reduced SARS-CoV-2 incidence in Dutch secondary schools. Widespread SARS-CoV-2 air contamination could not be demonstrated in schools under the prevailing conditions during the study.
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Affiliation(s)
- L Jonker
- Julius Center for Health Sciences and Primary Care, UMC Utrecht, Universiteitsweg 100, 3584 CG, Utrecht, The Netherlands
| | - K J Linde
- Institute for Risk Assessment Sciences, Utrecht University, Yalelaan 2, 3584 CM, Utrecht, the Netherlands
| | - A R de Boer
- Julius Center for Health Sciences and Primary Care, UMC Utrecht, Universiteitsweg 100, 3584 CG, Utrecht, The Netherlands.
| | - E Ding
- Faculty of Architecture and the Built Environment, Delft University of Technology, Julianalaan 134, 2628 BL, Delft, the Netherlands
| | - D Zhang
- Faculty of Architecture and the Built Environment, Delft University of Technology, Julianalaan 134, 2628 BL, Delft, the Netherlands
| | - M L A de Hoog
- Julius Center for Health Sciences and Primary Care, UMC Utrecht, Universiteitsweg 100, 3584 CG, Utrecht, The Netherlands
| | - S Herfst
- Department of Viroscience, Erasmus MC, Dr. Molewaterplein 50, 3015 GE, 3000 CA, Rotterdam, Netherlands
| | - D J J Heederik
- Institute for Risk Assessment Sciences, Utrecht University, Yalelaan 2, 3584 CM, Utrecht, the Netherlands
| | - P L A Fraaij
- Department of Viroscience, Erasmus MC, Dr. Molewaterplein 50, 3015 GE, 3000 CA, Rotterdam, Netherlands
- Department of Pediatrics, Erasmus MC, Dr. Molewaterplein 50, 3015 GE, 3000 CA, Rotterdam, Netherlands
| | - P M Bluyssen
- Faculty of Architecture and the Built Environment, Delft University of Technology, Julianalaan 134, 2628 BL, Delft, the Netherlands
| | - I M Wouters
- Institute for Risk Assessment Sciences, Utrecht University, Yalelaan 2, 3584 CM, Utrecht, the Netherlands
| | - P C J L Bruijning-Verhagen
- Julius Center for Health Sciences and Primary Care, UMC Utrecht, Universiteitsweg 100, 3584 CG, Utrecht, The Netherlands
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Ding E, Zhang D, Hamida A, García-Sánchez C, Jonker L, de Boer AR, Bruijning PCJL, Linde KJ, Wouters IM, Bluyssen PM. Ventilation and thermal conditions in secondary schools in the Netherlands: Effects of COVID-19 pandemic control and prevention measures. Build Environ 2023; 229:109922. [PMID: 36575741 PMCID: PMC9779948 DOI: 10.1016/j.buildenv.2022.109922] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 12/12/2022] [Accepted: 12/13/2022] [Indexed: 06/17/2023]
Abstract
During the COVID-19 pandemic, the importance of ventilation was widely stressed and new protocols of ventilation were implemented in school buildings worldwide. In the Netherlands, schools were recommended to keep the windows and doors open, and after a national lockdown more stringent measures such as reduction of occupancy were introduced. In this study, the actual effects of such measures on ventilation and thermal conditions were investigated in 31 classrooms of 11 Dutch secondary schools, by monitoring the indoor and outdoor CO2 concentration and air temperature, both before and after the lockdown. Ventilation rates were calculated using the steady-state method. Pre-lockdown, with an average occupancy of 17 students, in 42% of the classrooms the CO2 concentration exceeded the upper limit of the Dutch national guidelines (800 ppm above outdoors), while 13% had a ventilation rate per person (VRp) lower than the minimum requirement (6 l/s/p). Post-lockdown, the indoor CO2 concentration decreased significantly while for ventilation rates significant increase was only found in VRp, mainly caused by the decrease in occupancy (average 10 students). The total ventilation rate per classrooms, mainly induced by opening windows and doors, did not change significantly. Meanwhile, according to the Dutch national guidelines, thermal conditions in the classrooms were not satisfying, both pre- and post-lockdown. While opening windows and doors cannot achieve the required indoor environmental quality at all times, reducing occupancy might not be feasible for immediate implementation. Hence, more controllable and flexible ways for improving indoor air quality and thermal comfort in classrooms are needed.
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Affiliation(s)
- Er Ding
- Chair Indoor Environment, Faculty of Architecture and the Built Environment, Delft University of Technology, Delft, the Netherlands
| | - Dadi Zhang
- Chair Indoor Environment, Faculty of Architecture and the Built Environment, Delft University of Technology, Delft, the Netherlands
| | - Amneh Hamida
- Chair Indoor Environment, Faculty of Architecture and the Built Environment, Delft University of Technology, Delft, the Netherlands
| | - Clara García-Sánchez
- 3D Geoinformation Research Group, Faculty of Architecture and the Built Environment, Delft University of Technology, Delft, the Netherlands
| | - Lotte Jonker
- Julius Center for Health Sciences and Primary Care, UMC Utrecht, Utrecht University, Utrecht, the Netherlands
| | - Annemarijn R de Boer
- Julius Center for Health Sciences and Primary Care, UMC Utrecht, Utrecht University, Utrecht, the Netherlands
| | - Patricia C J L Bruijning
- Julius Center for Health Sciences and Primary Care, UMC Utrecht, Utrecht University, Utrecht, the Netherlands
| | - Kimberly J Linde
- Institute for Risk Assessment Sciences, Utrecht University, Utrecht, the Netherlands
| | - Inge M Wouters
- Institute for Risk Assessment Sciences, Utrecht University, Utrecht, the Netherlands
| | - Philomena M Bluyssen
- Chair Indoor Environment, Faculty of Architecture and the Built Environment, Delft University of Technology, Delft, the Netherlands
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Jonker L, Linde KJ, de Hoog MLA, Sprado R, Huisman RC, Molenkamp R, Oude Munnink BB, Dohmen W, Heederik DJJ, Eggink D, Welkers MRA, Vennema H, Fraaij PLA, Koopmans MPG, Wouters IM, Bruijning-Verhagen PCJL. SARS-CoV-2 outbreaks in secondary school settings in the Netherlands during fall 2020; silent circulation. BMC Infect Dis 2022; 22:960. [PMID: 36572861 PMCID: PMC9791966 DOI: 10.1186/s12879-022-07904-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 11/29/2022] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND In fall 2020 when schools in the Netherlands operated under a limited set of COVID-19 measures, we conducted outbreaks studies in four secondary schools to gain insight in the level of school transmission and the role of SARS-CoV-2 transmission via air and surfaces. METHODS Outbreak studies were performed between 11 November and 15 December 2020 when the wild-type variant of SARS-CoV-2 was dominant. Clusters of SARS-CoV-2 infections within schools were identified through a prospective school surveillance study. All school contacts of cluster cases, irrespective of symptoms, were invited for PCR testing twice within 48 h and 4-7 days later. Combined NTS and saliva samples were collected at each time point along with data on recent exposure and symptoms. Surface and active air samples were collected in the school environment. All samples were PCR-tested and sequenced when possible. RESULTS Out of 263 sampled school contacts, 24 tested SARS-CoV-2 positive (secondary attack rate 9.1%), of which 62% remained asymptomatic and 42% had a weakly positive test result. Phylogenetic analysis on 12 subjects from 2 schools indicated a cluster of 8 and 2 secondary cases, respectively, but also other distinct strains within outbreaks. Of 51 collected air and 53 surface samples, none were SARS-CoV-2 positive. CONCLUSION Our study confirmed within school SARS-CoV-2 transmission and substantial silent circulation, but also multiple introductions in some cases. Absence of air or surface contamination suggests environmental contamination is not widespread during school outbreaks.
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Affiliation(s)
- Lotte Jonker
- grid.7692.a0000000090126352Julius Center for Health Sciences and Primary Care, UMC Utrecht, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | - Kimberly J. Linde
- grid.5477.10000000120346234Institute for Risk Assessment Sciences, Utrecht University, Yalelaan 2, 3584 CM Utrecht, The Netherlands
| | - Marieke L. A. de Hoog
- grid.7692.a0000000090126352Julius Center for Health Sciences and Primary Care, UMC Utrecht, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | - Robin Sprado
- grid.7692.a0000000090126352Julius Center for Health Sciences and Primary Care, UMC Utrecht, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | - Robin C. Huisman
- grid.5645.2000000040459992XDepartment of Viroscience, Erasmus Medical Center, Dr. Molewaterplein 50, 3015 GD Rotterdam, The Netherlands
| | - Richard Molenkamp
- grid.5645.2000000040459992XDepartment of Viroscience, Erasmus Medical Center, Dr. Molewaterplein 50, 3015 GD Rotterdam, The Netherlands
| | - Bas B. Oude Munnink
- grid.5645.2000000040459992XDepartment of Viroscience, Erasmus Medical Center, Dr. Molewaterplein 50, 3015 GD Rotterdam, The Netherlands
| | - Wietske Dohmen
- grid.5477.10000000120346234Institute for Risk Assessment Sciences, Utrecht University, Yalelaan 2, 3584 CM Utrecht, The Netherlands
| | - Dick J. J. Heederik
- grid.5477.10000000120346234Institute for Risk Assessment Sciences, Utrecht University, Yalelaan 2, 3584 CM Utrecht, The Netherlands
| | - Dirk Eggink
- grid.31147.300000 0001 2208 0118Center for Infectious Disease Control, National Institute for Public Health and the Environment, Antonie Van Leeuwenhoeklaan 9, 3721 MA Bilthoven, The Netherlands
| | - Matthijs R. A. Welkers
- grid.31147.300000 0001 2208 0118Center for Infectious Disease Control, National Institute for Public Health and the Environment, Antonie Van Leeuwenhoeklaan 9, 3721 MA Bilthoven, The Netherlands ,grid.509540.d0000 0004 6880 3010Department of Medical Microbiology & Infection Prevention, Amsterdam University Medical Center, Meibergdreef 9, 1105AZ Amsterdam, The Netherlands
| | - Harry Vennema
- grid.31147.300000 0001 2208 0118Center for Infectious Disease Control, National Institute for Public Health and the Environment, Antonie Van Leeuwenhoeklaan 9, 3721 MA Bilthoven, The Netherlands
| | - Pieter L. A. Fraaij
- grid.5645.2000000040459992XDepartment of Viroscience, Erasmus Medical Center, Dr. Molewaterplein 50, 3015 GD Rotterdam, The Netherlands ,grid.416135.40000 0004 0649 0805Department of Pediatrics, Subdivision Infectious Diseases and Immunology, Erasmus Medical Center-Sophia Children’s Hospital, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands
| | - Marion P. G. Koopmans
- grid.5645.2000000040459992XDepartment of Viroscience, Erasmus Medical Center, Dr. Molewaterplein 50, 3015 GD Rotterdam, The Netherlands
| | - Inge M. Wouters
- grid.5477.10000000120346234Institute for Risk Assessment Sciences, Utrecht University, Yalelaan 2, 3584 CM Utrecht, The Netherlands
| | - Patricia C. J. L. Bruijning-Verhagen
- grid.7692.a0000000090126352Julius Center for Health Sciences and Primary Care, UMC Utrecht, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
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Linde KJ, Wouters IM, Kluytmans JAJW, Kluytmans-van den Bergh MFQ, Pas SD, GeurtsvanKessel CH, Koopmans MPG, Meier M, Meijer P, Raben CR, Spithoven J, Tersteeg-Zijderveld MHG, Heederik DJJ, Dohmen W. Detection of SARS-CoV-2 in Air and on Surfaces in Rooms of Infected Nursing Home Residents. Ann Work Expo Health 2022; 67:129-140. [PMID: 36068657 PMCID: PMC9834894 DOI: 10.1093/annweh/wxac056] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 07/12/2022] [Accepted: 07/29/2022] [Indexed: 01/14/2023] Open
Abstract
There is an ongoing debate on airborne transmission of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) as a risk factor for infection. In this study, the level of SARS-CoV-2 in air and on surfaces of SARS-CoV-2 infected nursing home residents was assessed to gain insight in potential transmission routes. During outbreaks, air samples were collected using three different active and one passive air sampling technique in rooms of infected patients. Oropharyngeal swabs (OPS) of the residents and dry surface swabs were collected. Additionally, longitudinal passive air samples were collected during a period of 4 months in common areas of the wards. Presence of SARS-CoV-2 RNA was determined using RT-qPCR, targeting the RdRp- and E-genes. OPS, samples of two active air samplers and surface swabs with Ct-value ≤35 were tested for the presence of infectious virus by cell culture. In total, 360 air and 319 surface samples from patient rooms and common areas were collected. In rooms of 10 residents with detected SARS-CoV-2 RNA in OPS, SARS-CoV-2 RNA was detected in 93 of 184 collected environmental samples (50.5%) (lowest Ct 29.5), substantially more than in the rooms of residents with negative OPS on the day of environmental sampling (n = 2) (3.6%). SARS-CoV-2 RNA was most frequently present in the larger particle size fractions [>4 μm 60% (6/10); 1-4 μm 50% (5/10); <1 μm 20% (2/10)] (Fischer exact test P = 0.076). The highest proportion of RNA-positive air samples on room level was found with a filtration-based sampler 80% (8/10) and the cyclone-based sampler 70% (7/10), and impingement-based sampler 50% (5/10). SARS-CoV-2 RNA was detected in 10 out of 12 (83%) passive air samples in patient rooms. Both high-touch and low-touch surfaces contained SARS-CoV-2 genome in rooms of residents with positive OPS [high 38% (21/55); low 50% (22/44)]. In one active air sample, infectious virus in vitro was detected. In conclusion, SARS-CoV-2 is frequently detected in air and on surfaces in the immediate surroundings of room-isolated COVID-19 patients, providing evidence of environmental contamination. The environmental contamination of SARS-CoV-2 and infectious aerosols confirm the potential for transmission via air up to several meters.
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Affiliation(s)
- Kimberly J Linde
- Author to whom correspondence should be addressed. Tel: +31302535358; e-mail:
| | - Inge M Wouters
- Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands
| | - Jan A J W Kluytmans
- Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Marjolein F Q Kluytmans-van den Bergh
- Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands,Department of Infection Control, Amphia Hospital, Breda, The Netherlands
| | - Suzan D Pas
- Microvida Location Amphia/Bravis, Breda/Roosendaal, The Netherlands
| | | | | | | | - Patrick Meijer
- Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands
| | - Ceder R Raben
- Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands
| | - Jack Spithoven
- Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands
| | | | - Dick J J Heederik
- Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands
| | - Wietske Dohmen
- Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands
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