Increased reports of severe myocarditis associated with enterovirus infection in neonates, United Kingdom, 27 June 2022 to 26 April 2023.

Enteroviruses are a common cause of seasonal childhood infections. The vast majority of enterovirus infections are mild and self-limiting, although neonates can sometimes develop severe disease. Myocarditis is a rare complication of enterovirus infection. Between June 2022 and April 2023, twenty cases of severe neonatal enteroviral myocarditis caused by coxsackie B viruses were reported in the United Kingdom. Sixteen required critical care support and two died. Enterovirus PCR on whole blood was the most sensitive diagnostic test. We describe the initial public health investigation into this cluster and aim to raise awareness among paediatricians, laboratories and public health specialists.

Trends in invasive Haemophilus influenzae serotype b (Hib) disease in England; 2012/13 to 2022/23.

INTRODUCTION: Haemophilus influenzae serotype b (Hib) conjugate vaccines have been highly successful in reducing the Hib disease worldwide. Recently, several European countries have reported an increase in invasive Hib disease. We aimed to describe the epidemiology, clinical characteristics, genomic trends, and outcomes of invasive Hib disease over the past 11 years in England. METHODS: The UK Health Security Agency (UKHSA) conducts national surveillance of invasive H influenzae disease and hosts a national reference laboratory for confirmation and serotyping. General practitioners are contacted to complete a surveillance questionnaire for confirmed Hib cases. Invasive Hib isolates routinely undergo whole genome sequencing. RESULTS: During 2012/13-2022/23, there were 6,881 invasive H. influenzae infections, of which 5,852 (85%) were serotyped; most isolates (4,881, 83%) were non-typeable H. influenzae, followed by Hif (591, 10%), Hie (189, 3%), Hib (118, 2%) and Hia (54, 1.0%). The median age for invasive Hib disease was 51 years and most cases (84%, 99/118) were in adults. Children accounted for 19 cases (16%), including 13 (11%) in <1 year-olds and 6 (5%) in 1-5-year-olds. Bacteraemic pneumonia was the most common diagnosis (66/118, 56%). Hib case-fatality rate was 5.9% (7/118), with the last fatality reported in 2016. Among 64 sequenced strains during 2016/17-2022/2023, most (56/64, 88%) belonged to the CC6 lineage (representing ST6 and single locus variants of ST6). CONCLUSIONS: In England, invasive Hib disease remains rare with no evidence of any increase in incidence and is rarely fatal, affecting mainly adults with underlying conditions, who typically develop pneumonia.

Trends in invasive Haemophilus influenzae serotype a disease in England from 2008-09 to 2021-22: a prospective national surveillance study.

BACKGROUND: Invasive Haemophilus influenzae serotype a (Hia) disease is rare, with most cases reported among Indigenous populations in North America. In England, national surveillance was enhanced following an increase in laboratory-confirmed invasive Hia disease since the 2016-17 epidemiological year. This study aimed to describe the epidemiological trends, clinical characteristics of cases, and assess potential genomic drivers. METHODS: Hospital laboratories in England routinely submit invasive H influenzae isolates to the UK Health Security Agency for confirmation and serotyping. In this prospective national surveillance study we contacted the general practitioners and clinicians of all patients with laboratory-confirmed invasive Hia from the 2008-09 to the 2021-22 epidemiological year to complete a clinical questionnaire on demographics, underlying conditions, clinical presentation, complications, outcomes, and travel history of the patient. All Hia invasive isolates from residents in England were included in the study; non-invasive isolates were excluded. Multilocus sequence typing (MLST), whole genome single-nucleotide polymorphism, and k-mer-based analysis of bacterial isolates were performed following Illumina whole-genome sequencing (WGS). Outcomes included epidemiological trends, clinical characteristics of confirmed Hia cases, and genomic analyses. FINDINGS: From the 2008-09 to the 2021-22 epidemiological years, there were 52 cases of invasive infection with H influenzae serotype a in England (25 [48%] in female patients and 27 [52%] in male patients). There were zero to two annual Hia cases (accounting for <0·5% of serotyped H influenzae isolates) until 2015-16, after which cases increased across England to 19 cases in 2021-22 (incidence 0·03 cases per 100 000), when Hia accounted for 19 (4%) of 484 serotyped H influenzae isolates, 19 (19%) of 100 capsulated cases, and 37% (19 of 52) of all H influenzae cases between 2008-09 and 2021-22. Most of the recent increase in cases occurred among individuals aged 65 years and older (17 [33%] of 52), who typically presented with bacteraemic pneumonia (13 [76%] of 17), and infants younger than 1 year, who had the highest incidence and were more likely to present with meningitis (five [50%] of ten). Overall case fatality rate was 7·7% (95% CI 2·1-19·7; four of 52 patients). WGS found that closely related MLST sequence types ST1511 (20 [39%] of 51), ST23 (13 [25%] of 51), and ST56 (seven [14%] of 51) accounted for most cases, with no evidence of serotype b strains switching capsule to Hia. Duplication of the capsule operon, associated with more severe disease, was present in 32 (80%) of 40 of these sequence types. Analysis of the core and accessory genome content grouped most isolates into a single strain. INTERPRETATION: The persistent increase in invasive Hia cases across England and across all age groups suggests widespread transmission, consistent with reports from other European countries, and will require close monitoring. FUNDING: UK Health Security Agency.