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Increasing reports of invasive Streptococcus pyogenes infections mandate surveillance for toxigenic lineage M1 UK . An allele-specific PCR was developed to distinguish M1 UK from other emm 1 strains. The M1 UK lineage represented 91% of invasive emm 1 isolates in England in 2020. Allele-specific PCR will permit surveillance for M1 UK without need for genome sequencing.

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Background. Transmission of SARS-CoV-2 by children and young people in school settings has not been directly evaluated, nor the main mechanisms of transmission identified. The study set out to undertake sequential longitudinal sampling of infected children, their contacts, and the environment. Methods. Cases of COVID-19 were identified through statutory notification and matched to schools reporting cases. Cases of COVID-19 and their contacts from school and home were longitudinally sampled and tested for SARS-CoV-2. Surfaces and air in the home and school environment were also subject to longitudinal sampling and testing. Results Onward transmission of virus to immediate classroom members who participated in the study was not detected. Evidence of more widespread transmission among children remaining in school was not identified with the exception of one unexpected cluster of three asymptomatic cases in one school. Children infected with SARS-CoV-2 in this study shed viral RNA for up to 10 days from symptom onset, with levels peaking at 5-8 days. Viral RNA was identified in the environment around children who were actively shedding virus in the home, but limited contamination was identified in schools. Variant of Concern B1.1.7 was identified in later cases studied. Summary After 3 months, this small study has not found evidence to suggest COVID-19 is commonly transmitted by children within schools. A minority of infections may be subject to stochastic events that can lead to transmission. Further prospective and retrospective studies are required to identify factors associated with such events .

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The Streptococcus pyogenes M1UK lineage, characterised by an intrinsic ability to express SpeA toxin and defined by 27 single nucleotide polymorphisms in the core genome, dominates the population of emm1 S. pyogenes isolates in England. The lineage has been identified elsewhere in Europe, North America, and, most recently, Australia. SpeA however may not be the sole deterministic factor underlying success of the M1UK lineage. Production of SpeA by strains belonging to an intermediate emm1 sublineage, M1-23SNP, is indistinguishable from M1UK strains. Despite this, in England at least, M1UK has outcompeted strains from the M1-23SNP sublineage. We infer that the fitness of M1UK resides in additional properties that confer an advantage to S. pyogenes, underlining a need for further research. A single nucleotide polymorphism (SNP) in the ssrA leader sequence upstream of speA is one of a limited number of SNPs that distinguish intermediate sublineages that differ in SpeA production. Introduction of the ssrA SNP into representative isolates of the widely disseminated M1global clone and the intermediate M1-13SNP lineage (that cannot otherwise produce readily-detectable SpeA in culture) resulted in SpeA expression, confirming the importance of the ssrA SNP to SpeA phenotype. However, RNAseq analysis of clinical strains showed that presence of the SNP was not invariably linked to read-through from the ssrA leader sequence or SpeA expression. Literature review suggests that read through and speA mRNA transcript length may be impacted by the two component regulator CovRS, pointing to a complex regulatory network interaction between the bacterial chromosome and phage-encoded superantigens.

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