Enterovirus D68 epidemic, UK, 2018, was caused by subclades B3 and D1, predominantly in children and adults respectively, with both subclades exhibiting extensive genetic diversity

Enterovirus D68 (EV-D68) has been recently identified in biennial epidemics coinciding with diagnoses of non-polio acute flaccid paralysis/myelitis (AFP/AFM). We investigated the prevalence, genetic relatedness and associated clinical features of EV-D68 in 194 known EV positive samples from late 2018, UK. EV-D68 was detected in 83 (58%) of the 143 EV positive samples. Sequencing and phylogenetic analysis revealed an extensive genetic diversity, split between subclades B3 (n=50) and D1 (n=33), suggesting epidemiologically unrelated infections. B3 predominated in children and younger adults, and D1 in older adults and the elderly (p=0.0009). Clinical presentation indicated causation or exacerbation of respiratory distress in 91.4% of EV-D68-positive individuals, principally: cough (75.3%), shortness of breath (56.8%), coryza (48.1%), wheeze (46.9%), supplemental oxygen required (46.9%) and fever (38.9%). Clinical features were not distinguished by subclade. Two cases of AFM were observed, one with EV-D68 detectable in the cerebrospinal fluid, otherwise neurological symptoms were rarely reported (n=4).