Rapid communication Re-emergence of enterovirus D68 in Europe after easing the COVID-19 lockdown, September 2021 Kimberley SM Benschop¹ , Jan Albert2,3 , Andres Anton⁴ , Cristina Andrés⁴ , Maitane Aranzamendi⁵ , Brynja Armannsdóttir⁶ , Jean-Luc Bailly 7,8 , Fausto Baldanti9,10 , Guðrún Erna Baldvinsdóttir⁶ , Stuart Beard11 , Natasa Berginc12 , Sindy Böttcher 13 , Soile Blomqvist14 , Laura Bubba15 , Cristina Calvo16 , Maria Cabrerizo17 , Annalisa Cavallero18 , Cristina Celma11 , Ferruccio Ceriotti19 , Inês Costa20 , Simon Cottrell21 , Margarita del Cuerpo22 , Jonathan Dean23 , Jennifer L Dembinski24 , Sabine Diedrich13 , Javier Diez-Domingo25 , DagnyHaug Dorenberg 24 , Erwin Duizer¹ , Robert Dyrdak 2,3 , Diana Fanti26 , Agnes Farkas27 , Susan Feeney28 , Jacky Flipse29 , Cillian De Gascun23 , Cristina Galli15 , Irina Georgieva30 , Laura Gifford21 , Raquel Guiomar 20 , Mario Hönemann31 , Niina Ikonen14 , Marion Jeannoël32 , Laurence Josset32 , Kathrin Keeren33 , F Xavier López-Labrador 25,34 , Melanie Maier 31 , James McKenna28 , Adam Meijer¹ , Beatriz Mengual-Chuliá25 , Sofie E Midgley 35 , Audrey Mirand7,8 , Milagrosa Montes⁵ , Catherine Moore21 , Ursula Morley23 , Jean-Luc Murk36 , Lubomira Nikolaeva-Glomb30 , Sanela Numanovic24 , Massimo Oggioni19 , Paula Palminha20 , Elena Pariani15 , Laura Pellegrinelli15 , Antonio Piralla⁹ , Corinna Pietsch31 , Luis Piñeiro⁵ , Núria Rabella22 , Petra Rainetova37 , Sara Colonia Uceda Renteria19 , María P Romero15 , Marijke Reynders37 , Lieuwe Roorda39 , Carita Savolainen-Kopra14 , Isabelle Schuffenecker 32 , Aysa Soynova30 , Caroline MA Swanink 29 , Tina Ursic 40 , Jaco J Verweij36 , Jorgina Vila 41 , Tytti Vuorinen42 , Peter Simmonds43 , Thea K Fischer44,45,* , Heli Harvala 46,47,* 1. Center for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, the Netherlands 2. Department of Clinical Microbiology, Karolinska University Hospital, Stockholm, Sweden 3. Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden 4. Respiratory Virus Unit, Microbiology Department, Vall d’Hebron Institut de Recerca (VHIR), Vall d’Hebron Barcelona Hospital Campus, Barcelona, Spain 5. Microbiology Department, Donostia University Hospital and Biodonostia Health Research Institute, San Sebastián, Spain 6. Landspitali-National University Hospital, Reykjavik, Iceland 7. CHU Clermont-Ferrand, National Reference Centre for enteroviruses and parechoviruses – Associated laboratory, Clermont-Ferrand, France 8. Université d’Auvergne, LMGE UMR CNRS 6023, Equipe EPIE - Epidémiologie et physiopathologie des infections à entérovirus, Faculté de Médecine, Clermont- Ferrand, France 9. Microbiology and Virology Department, Fondazione IRCCS Policlinico San Matteo, Italy 10. Department of Clinical Surgical Diagnostic and Pediatric Sciences, Università degli Studi di Pavia, Pavia, Italy 11. UK Health Security Agency, Colindale, United Kingdom 12. National laboratory of health, environment and food, Laboratory for public health virology, Ljubljana, Slovenia 13. National Reference Center for Poliomyelitis and Enteroviruses, Robert-Koch Institute, Berlin, Germany 14. National Institute for Health and Welfare, Helsinki, Finland 15. Department of Biomedical Sciences of Health, University of Milan, Milan, Italy 16. Hospital Universitario La Paz, Madrid, Spain 17. National Centre for Microbiology, Instituto de Salud Carlos III, Enterovirus and Viral Gastroenteritis Unit/Polio National Lab, Madrid, Spain 18. Laboratory of Microbiology, ASST Monza, San Gerardo Hospital, Monza (MB), Italy 19. Virology Unit, Division of Clinical Laboratory, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy 20. National Institute of Health (INSA), Lisbon, Portugal 21. Public Health Wales, Cardiff, United Kingdom 22. Microbiology Department Hospital Universitari de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain 23. National Virus Reference Laboratory, University College Dublin, Dublin, Ireland 24. Department of Virology, Norwegian Institute of Public Health, Oslo, Norway 25. Center for Public Health Research (FISABIO-Public Health), Generalitat Valenciana, Valencia, Spain 26. Chemical-clinical and Microbiological Analyses, ASST Grande Ospedale Metropolitano Niguarda, Milan, Italy 27. National Public Health Center, Budapest, Hungary 28. Regional Virus Laboratory, Belfast Health and Social Care Trust (BHSCT, Royal Victoria Hospital, Belfast, United Kingdom 29. Laboratory for Medical Microbiology and Immunology, Rijnstate, Velp, the Netherlands 30. National Reference Laboratory for Enteroviruses, National Center of Infectious and Parasitic Diseases, Sofia, Bulgaria 31. Institute of Medical Microbiology and Virology, University of Leipzig, Leipzig, Germany 32. National Reference Center for Enteroviruses and Parechoviruses, Institut des Agents Infectieux, Hospices Civils de Lyon, Lyon, France 33. Secretary of the commission for Polio Eradication in Germany, Robert-Koch Institute, Berlin, Germany 34. CIBERESP, Instituto de Salud Carlos III, Madrid, Spain 35. The Danish WHO National Reference Laboratory for Poliovirus, Statens Serum Institut, Copenhagen, Denmark 36. Elisabeth Tweesteden Hospital, Tilburg, the Netherlands 37. National Institute of Public Health, Prague, Czech Republic 38. Laboratory Medicine, Molecular Microbiology, AZ St.Jan Brugge-Oostende AV, Bruges, Belgium 39. Maasstad Hospital, Rotterdam, the Netherlands 40. Institute of Microbiology and Immunology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia 41. Pediatric Hospitalization Unit, Department of Pediatrics, Hospital Universitari Vall d’Hebron, Vall d’Hebron Barcelona Hospital Campus, Barcelona, Spain 42. Clinical Microbiology, Turku University Hospital and Institute of Biomedicine, University of Turku, Turku, Finland 43. University of Oxford, Oxford, United Kingdom 44. University of Sothern Denmark, Odense, Denmark 45. Nordsjaellands Hospital, Hillerod, Denmark 46. NHS Blood and Transplant, Microbiology Services, Colindale, United Kingdom 47. University College London (UCL), Department of infection and Immunity, London, United Kingdom * These authors contributed equally and share last authorship. Correspondence: Kimberley S.M. Benschop (kim.benschop@rivm.nl) Citation style for this article: Benschop Kimberley SM, Albert Jan, Anton Andres, Andrés Cristina, Aranzamendi Maitane, Armannsdóttir Brynja, Bailly Jean-Luc, Baldanti Fausto, Baldvinsdóttir Guðrún Erna, Beard Stuart, Berginc Natasa, Böttcher Sindy, Blomqvist Soile, Bubba Laura, Calvo Cristina, Cabrerizo Maria, Cavallero Annalisa, Celma Cristina, Ceriotti Ferruccio, Costa Inês, Cottrell Simon, del Cuerpo Margarita, Dean Jonathan, Dembinski Jennifer L, Diedrich Sabine, Diez-Domingo Javier, Dorenberg DagnyHaug, Duizer Erwin, Dyrdak Robert, Fanti Diana, Farkas Agnes, Feeney Susan, Flipse Jacky, De Gascun Cillian, Galli Cristina, Georgieva Irina, Gifford Laura, Guiomar Raquel, Hönemann Mario, Ikonen Niina, Jeannoël Marion, Josset Laurence, Keeren Kathrin, López-Labrador F Xavier, Maier Melanie, McKenna James, Meijer Adam, Mengual-Chuliá Beatriz, Midgley Sofie E, Mirand Audrey, Montes Milagrosa, Moore Catherine, Morley Ursula, Murk Jean-Luc, Nikolaeva-Glomb Lubomira, Numanovic Sanela, Oggioni Massimo, Palminha Paula, Pariani Elena, Pellegrinelli Laura, Piralla Antonio, Pietsch Corinna, Piñeiro Luis, Rabella Núria, Rainetova Petra, Uceda Renteria Sara Colonia, Romero María P, Reynders Marijke, Roorda Lieuwe, Savolainen-Kopra Carita, Schuffenecker Isabelle, Soynova Aysa, Swanink Caroline MA, Ursic Tina, Verweij Jaco J, Vila Jorgina, Vuorinen Tytti, Simmonds Peter, Fischer Thea K, Harvala Heli. Re-emergence of enterovirus D68 in Europe after easing the COVID-19 lockdown, September 2021. Euro Surveill. 2021;26(45):pii=2100998. https://doi.org/10.2807/1560-7917.ES.2021.26.45.2100998 Article submitted on 21 Oct 2021 / accepted on 09 Nov 2021 / published on 11 Nov 2021 We report a rapid increase in enterovirus D68 (EV- cases were identified in September, but more are to D68) infections, with 139 cases reported from eight be expected in the coming months. Reinforcement of European countries between 31 July and 14 October clinical awareness, diagnostic capacities and surveil- 2021. This upsurge is in line with the seasonality of lance of EV-D68 is urgently needed in Europe. EV-D68 and was presumably stimulated by the wide- spread reopening after COVID-19 lockdown. Most www.eurosurveillance.org 1 Table 1 Details for 36 institutions reporting to this study and number of EV-D68 cases identified via their enterovirus and EV-D68 surveillance systems, 18 European countries, 1 January–14 October 2021 (n = 139 cases) Use of Number Type of Enterovirus Samples subjected to EV-D68 Molecular EV Country Code EV-D68- of EV-D68 laboratory surveillance testing typing specific PCR cases Belgium BE-01 Hospital NA All clinical respiratory samples Yes No 14 Bulgaria BG-01 Public Health AFP and EVCS All EV-positive samples No No 0 Czechia CZ-01 Public Health EVCS Not currently in place No No 0 DE-01 Public Health EVCS Limited respiratory samplesa No In-house 0 Germany DE-02 Academic Hospital ILI/ARI EV-positive samples No In-house 0 Denmark DK-01 Public Health ILI/ARI and EVCS All EV-positive samples No In-house 0 ES-01 Academic Hospital EVCS All EV-positive samples No In-house 9 ES-02 Academic Hospital EVCS All EV-positive samples No In-house 1 ES-03 Academic Hospital NA All EV-positive samples No ES-05 0 Spain ES-04 Academic Hospital NA NK NK NK 0 ES-05 Public Health AFP and EVCS All EV-positive samples No In-house 0 ES-06 Public Health ILI/ARI EV-positive repiratory samples No In-house 0 FI-01 Academic Hospital NA EV-positive samples No In-house 0 Finland FI-02 Public Health ILI/ARI EV-positive repiratory samples Yes In-house 0 All EV-positive samples and FR-01 Academic Hospital EVCS all HRV-EV positive respiratory No In-house 14 France samples FR-02 Public Health EVCS All EV-positive samples Yes In-house 6 Hungary HU-01 Public Health AFP and EVCS All EV-positive samples No In-house 0 Proportion of EV-positive Ireland IE-01 Public Health EVCS Yes In-house 1 respiratory samples Iceland IS-01 Public Health EVCS All EV-positive samples Yes In-house 0 IT-01 Public Health ILI/ARI and AFP All EV-positive samples Yes In-house 1 IT-02 Academic Hospital ILI/ARI All clinical respiratory samples Yes In-house 0 Italy IT-03 Academic Hospital NA All clinical respiratory samples No IT-01/IT-02 0 IT-04 Hospital NA All clinical respiratory samples No IT-01/IT-02 0 IT-05 Hospital NA All clinical respiratory samples No IT-01/IT-02 0 NL-01 Hospital NA All clinical respiratory samples No In-house 1 NL-02-A EVCS All EV-positive samples No In-house 1 Public Health The Netherlands NL-02-B ILI/ARI All clinical respiratory samples Yes In-house 0 NL-03 Hospital NA All clinical respiratory samples No In-house 0 NL-04 Hospital NA All clinical respiratory samples No In-house 0 Norway NO-01 Public Health AFP and EVCS All EV-positive samples Yes In-house 0 Portugal PT-01 Public Health NA All clinical respiratory samples No No 0 All clinical respiratory and Sweden SE-01 Academic Hospital NA Yes In-house b 2 EV-positive samples SI-01 Public Health ILI/ARI and AFP All EV-positive samples No In-house 0 Slovenia SI-02 Academic Hospital NA Mostly respiratory samples Yes In-house 0 England, UK UK-01 Public Health EVCS All EV-positive samples Yes In-house 7 Wales, UK UK-02 Public Health ILI/ARI and EVCS All EV-positive samples Yes In-house 82 Belfast, UK UK-03 Hospital NA Any samples if clinically indicated Yes In-house 0 AFM: acute flaccid myelitis surveillance; AFP: acute flaccid paralysis surveillance; EV: enterovirus; EVCS: EV clinical surveillance (i.e. EV-positive clinical specimens are subjected to typing); HRV: human rhinovirus; ILI/ARI: sentinel influenza surveillance focusing on influenza like illness and acute respiratory infection; NA: not applicable; NK: not known; UK: United Kingdom. a Only if respiratory sample has been taken from a case with acute flaccid paralysis. b EV-positive faecal and central nervous system samples referred for typing at public health agency. 2 www.eurosurveillance.org Table 2 Laboratory details for enterovirus detection and typing, 18 European countries, 1 January–14 October 2021 (n = 36 laboratories) Country Code EV and screening methods EV sequencing methods Faeces: EV PCR on GI-TAC assay; respiratory samples: EV PCR and EV-D68 PCR Belgium BE-01 NA on respiratory TAC assay; others: in-house EV PCR; CSF: FilmArray panel Bulgaria BG-01 All samples: cell culture (A), and EV PCR (B) NA Czechia CZ-01 Faeces: cell culture and EV PCR NA DE-01 Only faeces and CSF tested, respiratory (only AFP cases): EV PCR Complete or partial VP1 region Germany DE-02 All samples: EV-PCR and EV/HRV PCR Partial VP1 Partial VP1 and VP4-VP2 for EV, VP2 Denmark DK-01 All samples: EV PCR and HRV PCR for RV All samples: HRV16 Allplex Respiratory Panel (Seegene) or RealCycle EV/hPeV ES-01 Partial VP1 detection (Progenie) ES-02 Respiratory samples: Allplex Respiratory Panel; other samples: EV PCR Partial VP1 All respiratory samples negative for other respiratory viruses, CSF and faeces Spain ES-03 Partial VP1 from neurological or cutaneous illnesses ES-04 No data Partial VP1 ES-05 All samples: EV PCR Partial VP1 ES-06 Respiratory samples: respiratory RT-PCR panel (EV/HRV in one channel) EV-D68 typing PCR FI-01 Respiratory samples: EV/HRV PCR], All samples: EV-PCR Partial VP1 Finland FI-02 Respiratory samples: EV/HRV PCR and EV-D68 PCR Complete VP1 and VP4-VP2 Complete or partial VP1 and FR-01 Respiratory samples: EV/HRV PCR VP4-VP2 France FR-02-A All samples: EV PCR and EV/HRV PCR Complete or partial VP1 and Respiratory samples (< 5 years) or samples from severe cases (respiratory VP4-VP2; complete or partial VP1 FR-02-B and VP4-VP2 AFM): EV-D68 PCR Hungary HU-01 All samples: EV PCR 5’-NTR, partial VP1 Respiratory samples: Luminex NxTAG Respiratory Panel (EV/HRV); respiratory Ireland IE-01 Partial VP1 samples with clinical indication: EV-D68 PCR; all other samples: EV PCR Iceland IS-01 All samples: EV PCR and EV-D68 PCR Partial VP1 IT-01 Respiratory samples: EV PCR and EV-D68 PCR Partial VP1 and VP4-VP2 EV-D68 typing; HRV/EV on VP4/VP2 typing IT-02 Respiratory samples: EV/HRV PCR and EV-D68 PCR Italy VP1 typing IT-03 Respiratory samples: EV PCR: Allplex Respiratory Panel NA IT-04 Respiratory samples: EV PCR: Allplex Respiratory Panel NA IT-05 Respiratory samples: EV PCR: Allplex Respiratory Panel NA NL-01 All samples: EV PCR Partial VP1 NL-02-A All samples: EV PCR Partial VP1 The NL-02-B Respiratory samples: EV PCR and HRV PCR and EV-D68 PCR 5’-NTR, EV-D68 VP1, partial VP1 Netherlands NL-03 All samples: EV PCR Partial VP1 NL-04 All samples: EV PCR Partial VP1 Norway NO-01 All samples: EV PCR and EV-D68 PCR Partial VP1 Portugal PT-01 Respiratory samples: EV PCR: Allplex Respiratory Panel NA SE-01-A Non-respiratory samples: EV PCR Partial VP1 and VP4-VP2 Sweden SE-01-B Respiratory samples: Allplex Respiratory Panel and EV-D68 PCR Partial VP1 and VP4-VP2 SI-01 Respiratory samples: EV PCR Partial VP1 Slovenia SI-02 All samples: EV-D68 PCR Partial VP1 England, UK UK-01 All samples: EV PCR and EV-D68 PCR Partial VP1 Wales, UK UK-02 All respiratory samples/CNS/faeces: EV PCR and EV-D68 PCR Partial VP1 Respiratory samples with clinical indication; skin swab with clinical Partial VP1 Colindale reference Belfast, UK UK-03 indication; all CSF samples; blood with clinical symptoms; EV PCR and laboratory sequencing EV-D68 PCR AFM: acute flaccid myelitis; CSF: cerebrospinal fluid; EV: enterovirus; GI-TAC: gastrointestinal Taqman array card; hPeV: human parechovirus; HRV: human rhinovirus; NA: not applicable; NTR: non-translated region; UK: United Kingdom; VP: viral protein. References for the methods presented here are listed in the Supplement. www.eurosurveillance.org 3 Figure 1 laboratories (in the Czech Republic and Germany) had EV-D68 detection in Europe, 1 July–14 October 2021 not included respiratory samples in their EV surveil- (n = 139) lance. Data on screening and typing were supplied by 33 laboratories. All except one of the 14 hospital labo- 120 Reporting laboratory ratory tested respiratory samples for EV-D68. The use IT-01 of EV-D68-specific PCR was reported by 13 of 33 labo- UK-02 IE-01 UK-01 ratories, and genetic characterisation by sequencing 100 BE-01 NL-02 was applied in most laboratories (28/33, Table 2). ES-02 NL-01 ES-01 FR-02 Distribution of enterovirus D68 cases in SE-01 FR-01 Europe 80 A total of 139 EV-D68 cases were identified between Number of reported cases 31 July and 14 October 2021 by 12 laboratories in eight countries (Table 1). Most EV-D68-positive samples 60 were collected in September (99/139, 71%, Figure). Screening and typing of samples collected in October is ongoing. 40 Number of EV-D68 infections is increasing in Europe Denominator data were available from 24 labora- 20 tories reporting 66 of 139 EV-D68 cases. Since the beginning of 2021, these laboratories identified 1,964 EV-positive samples by screening 56,401 samples by EV PCR (some also detecting and hence including 0 rhinoviruses in these reports). While the number of July August September Octobera samples tested monthly remained unchanged (on aver- age 6,113 samples screened monthly between January Sample collection on month and July, 5,170 in August and 6,353 in September), an increase in the positivity rate was noted (overall 2.5% BE: Belgium; ES: Spain; EV: enterovirus; FR: France; IE: Ireland; IT: in January through July, 4.5% in August and 8.2% in Italy; NL: the Netherlands; SE: Sweden; UK: United Kingdom. September). A total of 967 samples were typed as EV a Data incomplete based on samples collected and reported as EV- and 36 as EV-D68. The proportion of samples identi- D68 by 14 October 2021. fied as EV-D68 increased from 0.2% in January through July (1/409) and 0.9% in August (2/208) to 14% in September (33/236; p < 0.0001 by chi-squared test). An additional 30 EV-D68-positive samples were iden- Coordination of case reporting by the European Non- tified by screening of 8,243 respiratory samples by Polio Enterovirus Network (ENPEN) found evidence for EV-D68-specific PCR in 13 laboratories. Of these, none increasing numbers of enterovirus D68 (EV-D68) infec- was identified before August despite screening of tions in Europe in September 2021. This prompted the 5,088 samples since January (monthly average: 727 consortium to send an alert email to member laborato- samples). Three EV-D68 positive samples were iden- ries, requesting an urgent EV-D68 investigation. Here, tified in August (3/739; 0.4%) and 27 in September we report the virological and clinical characteristics of and October (27/1,289; 2%) demonstrating a recent 139 EV-D68 cases identified in eight European coun- but significant increase in the EV-D68 positivity rate tries between 31 July and 14 October 2021. (p < 0.0001 by chi-squared test). Clinical characteristics of enterovirus D68 Enterovirus D68 detection and typing cases A total of 36 institutions including 19 public health and Demographic information was collected for all reported 17 hospital laboratories from 18 European countries EV-D68 cases (Table 3). Most were males (88/139; responded to the ENPEN alert (Table 1). 63%) and younger than 5 years (120/139; 86%), with a median age of 3 years (range: newborns to 72 years). We requested data on EV-D68 cases and detection Clinical symptoms were reported for 120 cases, with methods. The 19 public health laboratories from 13 most exhibiting respiratory symptoms (n = 116; 97%). countries indicated that they would identify EV-D68 Although five cases had neurological symptoms, infections either via their EV surveillance (n = 14), sur- none was diagnosed with AFP or acute flaccid myeli- veillance focusing on influenza-like illness (ILI) and/ tis (AFM). Thirty of 49 cases with data on hospitalisa- or acute respiratory infection (ARI; n = 8), or via sur- tion were hospitalised. Pre-existing conditions were veillance for acute flaccid paralysis (AFP) (n = 6). Two reported for 20 of 45 cases with available information, 4 www.eurosurveillance.org Table 3 regular EV-D68 upsurges have been reported in Europe Demographic and clinical characteristics of individuals since 2010 [2-7], they largely ceased during the coro- with a laboratory-confirmed EV-D68 infection, eight European countries, 1 September–14 October 2021 navirus disease (COVID-19) pandemic. Here we report (n = 139) EV-D68 circulation across Europe for the first time fol- lowing the COVID-19 pandemic, with case numbers Number Proportion already exceeding what was reported during the most of cases of cases recent EV-D68 upsurge in 2019 [7]. Age group 0–3 months 7 5% Although EV-D68 circulation in Europe has largely fol- 4–12 months 15 11% lowed a biennial epidemic pattern confined to the 13–24 months 22 16% autumn season of even-numbered years, the autumn of 2–5 years 76 55% 2019 showed an unexpected upsurge of EV-D68 infec- 6–15 years 9 6% tions leading to 93 reported cases, two with AFM, in five European countries [7]. EV-D68 has largely been 16–25 years 2 1% detected through ILI/ARI sentinel surveillance because 26–45 years 2 1% of its respiratory signature and in EV surveillance sys- > 45 years 6 4% tems which have included respiratory samples since Sex the occurrence of the first large outbreak of EV-D68 in Female 51 37% Europe and North America where these samples were Male 88 63% recommended [8,9]. Several institutes have addition- Symptoms (data reported for) ally included EV-D68-specific PCR for their respiratory Any symptom reported (n = 121) 120 99% surveillance. Fever (n = 111) 49 44% Enteric symptoms (n = 120) 4 3% The timing of this increase in the number of EV-D68 Respiratory symptoms (n = 120) 116 97% infections is consistent with the known seasonality of Neurological symptomsa (n = 111) 5 5% EV, with numbers usually peaking in September and Clinical information (data reported for) October [10]. However, this marked upsurge is likely Hospitalised (n = 49) 30 to have been further precipitated by the widespread relaxation of COVID-19 mitigation measures such as Pre-existing conditionb (n = 45) 20 travel restrictions, school closures, use of face masks Co-infections (data reported for) and physical distancing. The findings are indeed Any co-infection reported (n = 43) 16 consistent with the widespread resurgence of other Adenovirus 4 community-transmitted respiratory infections, whose Rhinovirus 6 circulation in most of Europe had until recently largely Human metapneumovirus 1 ceased [11,12]. The interruption in the transmission of Adenovirus and rhinovirus 1 respiratory and enteric viruses, including EV-D68, has Adenovirus and bocavirus 1 probably created large cohorts of susceptible young Rhinovirus and SARS-CoV-2 1 children without prior exposure or immunity to any PIV4 and CMV 1 such virus, potentially creating the conditions for lar- Rhinovirus, bocavirus and PIV3 1 gescale outbreaks of severe respiratory disease in this age group this winter. CMV: cytomegalovirus; EV: enterovirus; PIV: parainfluenza virus; SARS-CoV-2: severe acute respiratory syndrome coronavirus 2. a Reported neurological symptoms included headache, dizziness As circulation of EV diminished during the lockdown, and agitation. many of the surveillance systems not related to SARS- b Reported pre-existing conditions were asthma, chronic CoV-2 were temporarily discontinued or received fewer obstructive pulmonary disease, sleep apnoea and immunosuppression. specimens because testing facilities prioritised SARS- CoV-2. Although most study participants have now re-started active investigations via established sur- veillance systems, it is also important to consider the predominantly in older age groups (2/14 < 2 years, minimum number of samples needed for effective sur- 18/31 > 2 years). Viral co-infection was reported for 16 veillance. Nonetheless, laboratories in 16 countries use cases; the most common co-detection was rhinovirus screening or surveillance systems that enable detec- (n = 9). To date, genotyping of 20 EV-D68 positive sam- tion of EV-D68 infection through typing of EV-positive ples has shown all strains to be genotype B3 (data not samples. At the time of our previous survey on the EV shown). laboratory and surveillance capacity in Europe in 2016, only 11 countries had introduced or modified their Discussion existing surveillance systems to enable EV-D68 detec- Enterovirus D68 (EV-D68) infections have been linked tion [8]. This clearly demonstrates increased capacity to AFP/AFM since a large outbreak associated with res- for detection and awareness of EV-D68 across Europe, piratory and neurological symptoms in children was probably a sign of the strength of the continued collab- described in North America in 2014 [1,2]. Although oration established through ENPEN [9,13-16]. Notably, www.eurosurveillance.org 5 reviewed and edited manuscript. All authors have accepted the zero-reporting noted by two countries in this study the final version of manuscript. was due to the exclusion of respiratory samples from their EV surveillance, an important reminder that a res- piratory sample is needed for the detection of EV-D68 References (even in cases of AFM) as the virus is only rarely 1. Aliabadi N, Messacar K, Pastula DM, Robinson CC, Leshem detected in faecal or cerebrospinal fluid samples [9]. E, Sejvar JJ, et al. Enterovirus D68 Infection in Children with Acute Flaccid Myelitis, Colorado, USA, 2014. Emerg Infect Dis. 2016;22(8):1387-94. https://doi.org/10.3201/eid2208.151949 Our data clearly demonstrate that EV-D68 is now cir- PMID: 27434186 culating in Europe, mostly affecting children or those 2. Midgley CM, Watson JT, Nix WA, Curns AT, Rogers SL, Brown BA, et al. Severe respiratory illness associated with a with underlying conditions. 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Surveillance and laboratory detection for non-polio This study shows that EV-D68 cases can be identified enteroviruses in the European Union/European Economic Area, 2016. Euro Surveill. 2017;22(45):16-00807. https:// through a combination of ILI/ARI sentinel surveillance doi.org/10.2807/1560-7917.ES.2017.22.45.16-00807 PMID: and EV surveillance expanded to include respiratory 29162204 9. Harvala H, Broberg E, Benschop K, Berginc N, Ladhani S, samples. It calls for continued careful monitoring and Susi P, et al. Recommendations for enterovirus diagnostics vigilant testing of respiratory samples. and characterisation within and beyond Europe. J Clin Virol. 2018;101:11-7. https://doi.org/10.1016/j.jcv.2018.01.008 PMID: 29414181 10. Bubba L, Broberg E, Jasir A, Simmonds P, Participants ES, Acknowledgements Harvala H. Circulation of non-polioviruses in 24 EU/EAA countries between 2015 and 2017 - is it time to consider The authors wish to thank the European Society for Clinical systematic surveillance? Lancet Infect Dis. 2019. Forthcoming. Virology for hosting the European Non-Polio Enterovirus 11. van Summeren J, Meijer A, Aspelund G, Casalegno JS, Erna G, Network (ENPEN). The authors would also like to thank eve- Hoang U, et al. Low levels of respiratory syncytial virus activity rybody who contributed to the collection, testing and report- in Europe during the 2020/21 season: what can we expect in the coming summer and autumn/winter? Euro Surveill. ing of clinical and virological data presented in this study. 2021;26(29):2100639. https://doi.org/10.2807/1560-7917. ES.2021.26.29.2100639 PMID: 34296672 12. von Hammerstein AL, Aebi C, Barbey F, Berger C, Buettcher M, Casaulta C, et al. Interseasonal RSV infections in Switzerland Conflict of interest - rapid establishment of a clinician-led national reporting system (RSV EpiCH). Swiss Med Wkly. 2021;151:w30057. PMID: None declared. 34499459 13. Poelman R, Schuffenecker I, Van Leer-Buter C, Josset L, Niesters HG, Lina BEuropean surveillance for enterovirus D68 during the emerging North-American outbreak in 2014. J Clin Authors’ contributions Virol. 2015;71:1-9. https://doi.org/10.1016/j.jcv.2015.07.296 PMID: 26364237 KB, TF and HH initiated the study. KB and HH wrote the first draft, prepared the tables and figures, as well as the final 14. Benschop KSM, Broberg EK, Hodcroft E, Schmitz D, Albert J, Baicus A, et al. Molecular epidemiology and evolutionary manuscript. PS and TF helped with drafting the manuscript. trajectory of emerging echovirus 30, Europe. Emerg Infect Dis. JA, AA, CA, MA, BA, JB, FB, GB, SuB, NB, SiB, SoB, LB, CC, 2021;27(6):1616-26. https://doi.org/10.3201/eid2706.203096 MC, AC, CC, FC, IC, SC, MC, JD, JLD, SD, JDD, DD, ED, RD, DF, PMID: 34013874 AG, SF, JF, CDG, CG, IG, LG, RG, MH, NI, MJ, LJ, KK, XL, MeM, 15. Harvala H, Benschop KSM, Berginc N, Midgley S, Wolthers JM, AdM, BM, SM, AuM, MiM, CM, UM, JM, LN, SN, MO, PP, K, Simmonds P, et al. European non-polio enterovirus network: introduction of hospital-based surveillance EP, LP, AP, CP, LP, NR, PR, SC, MR, MR, LR, CS, IS, AS, CS, TU, network to understand the true disease burden of non- JJV, JV and TV were responsible for testing and data collec- polio enterovirus and parechovirus infections in Europe. tion. All other authors provided and checked data, critically 6 www.eurosurveillance.org Microorganisms. 2021;9(9):1827. https://doi.org/10.3390/ microorganisms9091827 PMID: 34576722 16. Fischer TK, Simmonds P, Harvala H. The importance of enterovirus surveillance in a post-polio world. Lancet Infect Dis. 2021;S1473-3099(20)30852-5. PMID: 34265258 17. Knoester M, Helfferich J, Poelman R, Van Leer-Buter C, Brouwer OF, Niesters HGM. Twenty-nine cases of enterovirus-D68- associated acute flaccid myelitis in Europe 2016: A case series and epidemiologic overview. Pediatr Infect Dis J. 2019;38(1):16- 21. https://doi.org/10.1097/INF.0000000000002188 PMID: 30234793 18. Kirolos A, Mark K, Shetty J, Chinchankar N, Mcdougall C, Eunson P, et al. Outcome of paediatric acute flaccid myelitis associated with enterovirus D68: a case series. Dev Med Child Neurol. 2019;61(3):376-80. https://doi.org/10.1111/ dmcn.14096 PMID: 30417347 19. Yea C, Bitnun A, Robinson J, Mineyko A, Barton M, Mah JK, et al. Longitudinal outcomes in the 2014 acute flaccid paralysis cluster in Canada. J Child Neurol. 2017;32(3):301-7. https://doi. org/10.1177/0883073816680770 PMID: 28193112 20. Aubart M, Gitiaux C, Roux CJ, Levy R, Schuffenecker I, Mirand A, et al. Severe acute flaccid myelitis associated with enterovirus in children: two phenotypes for two evolution profiles? Front Neurol. 2020;11:343. https://doi.org/10.3389/ fneur.2020.00343 PMID: 32411086 License, supplementary material and copyright This is an open-access article distributed under the terms of the Creative Commons Attribution (CC BY 4.0) Licence. You may share and adapt the material, but must give appropriate credit to the source, provide a link to the licence and indicate if changes were made. Any supplementary material referenced in the article can be found in the online version. This article is copyright of the authors or their affiliated in- stitutions, 2021. www.eurosurveillance.org 7