Background: The impact of SARS-CoV-2 alongside influenza is a major concern in the northern hemisphere as winter approaches. Methods: Test data for influenza and SARS-CoV-2 from national surveillance systems between 20 January 2020 and 25 April 2020 were used to estimate influenza infection on the risk of SARS-CoV-2 infection. A test-negative design was used to assess the odds of SARS-CoV-2 in those who tested positive for influenza compared with those who tested negative. The severity of SARS-CoV-2 was also assessed using univariable and multivariable analyses. Results: The risk of testing positive for SARS-CoV-2 was 58% lower among influenza-positive cases and patients with a coinfection had a risk of death of 5.92 (95% confidence interval: 3.21–10.91) times greater than among those with neither influenza nor SARS-CoV-2. The odds of ventilator use or death and intensive care unit admission or death were greatest among coinfected patients. Conclusions: Coinfection of these viruses could have a significant impact on morbidity, mortality and health-service demand.

Increases in invasive group A streptococcal (iGAS) infection and associated deaths, particularly in children, above seasonally expected levels are being seen this season (772 notifications reported in weeks 37 to 48 in 2022) across England. Diagnoses of iGAS infection from lower respiratory tract specimens in children under 15 years increased to 28% in November 2022. Medical practitioners have been alerted to the exceptional increase in incidence, including unusual numbers of children presenting with pulmonary empyema.

After decades of decreasing scarlet fever incidence, a dramatic increase was seen in England beginning in 2014. Investigations were launched to assess clinical and epidemiological patterns and identify potential causes. In this population-based surveillance study, we analysed statutory scarlet fever notifications held by Public Health England from 1911 to 2016 in England and Wales to identify periods of sudden escalation of scarlet fever. Characteristics of cases and outbreaks in England including frequency of complications and hospital admissions were assessed and compared with the pre-upsurge period. Isolates from throat swabs were obtained and were emm typed. Data were retrieved for our analysis between Jan 1, 1911, and Dec 31, 2016. Population rates of scarlet fever increased by a factor of three between 2013 and 2014 from 8·2 to 27·2 per 100 000 (rate ratio [RR] 3·34, 95% CI 3·23-3·45; p<0·0001); further increases were observed in 2015 (30·6 per 100 000) and in 2016 (33·2 per 100 000), which reached the highest number of cases (19 206) and rate of scarlet fever notifcation since 1967. The median age of cases in 2014 was 4 years (IQR 3-7) with an incidence of 186 per 100 000 children under age 10 years. All parts of England saw an increase in incidence, with 620 outbreaks reported in 2016. Hospital admissions for scarlet fever increased by 97% between 2013 and 2016; one in 40 cases were admitted for management of the condition or potential complications. Analysis of strains (n=303) identified a diversity of emm types with emm3 (43%), emm12 (15%), emm1 (11%), and emm4 (9%) being the most common. Longitudinal analysis identified 4-yearly periodicity in population incidence of scarlet fever but of consistently lower magnitude than the current escalation. England is experiencing an unprecedented rise in scarlet fever with the highest incidence for nearly 50 years. Reasons for this escalation are unclear and identifying these remains a public health priority. None.

Few cross-population studies examining the epidemiology of invasive group B streptococcal (GBS) disease have been undertaken. To identify longitudinal trends in the burden and characteristics of infections, national surveillance data on diagnoses in England and Wales from 1991 to 2010 were analyzed. A parallel review of laboratory-confirmed invasive GBS infection surveillance reports and isolates submitted to the national reference laboratory was undertaken. Cases were defined as GBS isolated from a normally sterile site. A total of 21 386 reports of invasive GBS infection were made between 1991 and 2010. The annual rate of reports doubled over the 20 years from 1.48 to 2.99 per 100 000 population. Significant increases were seen in all age groups but most pronounced in adults. Rates of early-onset (0–6 days) infant disease fluctuated but showed a general rise between 2000 and 2010 from 0.28 to 0.41 per 1000 live births. Rates of late-onset (7–90 days) disease increased steadily between 1991 and 2010 from 0.11 to 0.29 per 1000 live births. Resistance to erythromycin increased markedly from 2.5% in 1991 to 15% in 2010. The distribution of serotypes varied according to patient age and over time with type III increasing among early-onset cases and decreasing in adults. Although risk of invasive GBS infection remains highest within the first few days of life, the relative burden of disease is shifting toward adults. The rise in incidence and antibiotic resistance makes development of an effective and safe vaccine all the more pressing.

The UK observed a marked increase in scarlet fever and invasive group A streptococcal infection in 2022 with severe outcomes in children and similar trends worldwide. Here we report lineage M1_UK to be the dominant source of invasive infections in this upsurge. Compared with ancestral M1_global strains, invasive M1_UK strains exhibit reduced genomic diversity and fewer mutations in two-component regulator genes covRS. The emergence of M1_UK is dated to 2008. Following a bottleneck coinciding with the COVID-19 pandemic, three emergent M1_UK clades underwent rapid nationwide expansion, despite lack of detection in previous years. All M1_UK isolates thus-far sequenced globally have a phylogenetic origin in the UK, with dispersal of the new clades in Europe. While waning immunity may promote streptococcal epidemics, the genetic features of M1_UK point to a fitness advantage in pathogenicity, and a striking ability to persist through population bottlenecks.

The incidence of invasive disease caused by group A streptococcus (GAS) has increased in multiple countries in the past 15 years. However, despite these reports, to the best of our knowledge, no systematic reviews and combined estimates of the incidence of invasive GAS have been done in key high-risk groups. To address this, we estimated the incidence of invasive GAS disease, including death and disability outcomes, among two high-risk groups—namely, pregnant women and children younger than 5 years. We did a systematic review and meta-analyses on invasive GAS outcomes, including incidence, case fatality risks, and neurodevelopmental impairment risk, among pregnant women, neonates (younger than 28 days), infants (younger than 1 year), and children (younger than 5 years) worldwide and by income region. We searched several databases for articles published from Jan 1, 2000, to June 3, 2020, for publications that reported invasive GAS outcomes, and we sought unpublished data from an investigator group of collaborators. We included studies with data on invasive GAS cases, defined as laboratory isolation of Streptococcus pyogenes from any normally sterile site, or isolation of S pyogenes from a non-sterile site in a patient with necrotising fasciitis or streptococcal toxic shock syndrome. For inclusion in pooled incidence estimates, studies had to report a population denominator, and for inclusion in pooled estimates of case fatality risk, studies had to report aggregate data on the outcome of interest and the total number of cases included as a denominator. We excluded studies focusing on groups at very high risk (eg, only preterm infants). We assessed heterogeneity with I². Of the 950 published articles and 29 unpublished datasets identified, 20 studies (seven unpublished; 3829 cases of invasive GAS) from 12 countries provided sufficient data to be included in pooled estimates of outcomes. We did not identify studies reporting invasive GAS incidence among pregnant women in low-income and middle-income countries (LMICs) nor any reporting neurodevelopmental impairment after invasive GAS in LMICs. In nine studies from high-income countries (HICs) that reported invasive GAS in pregnancy and the post-partum period, invasive GAS incidence was 0·12 per 1000 livebirths (95% CI 0·11 to 0·14; I²=100%). Invasive GAS incidence was 0·04 per 1000 livebirths (0·03 to 0·05; I²=100%; 11 studies) for neonates, 0·13 per 1000 livebirths (0·10 to 0·16; I²=100%; ten studies) for infants, and 0·09 per 1000 person-years (95% CI 0·07 to 0·10; I²=100%; nine studies) for children worldwide; 0·12 per 1000 livebirths (95% CI 0·00 to 0·24; I²=100%; three studies) in neonates, 0·33 per 1000 livebirths (−0·22 to 0·88; I²=100%; two studies) in infants, and 0·22 per 1000 person-years (0·13 to 0·31; I²=100%; two studies) in children in LMICs; and 0·02 per 1000 livebirths (0·00 to 0·03; I²=100%; eight studies) in neonates, 0·08 per 1000 livebirths (0·05 to 0·11; I²=100%; eight studies) in infants, and 0·05 per 1000 person-years (0·03 to 0·06; I²=100%; seven studies) in children for HICs. Case fatality risks were high, particularly among neonates in LMICs (61% [95% CI 33 to 89]; I²=54%; two studies). We found a substantial burden of invasive GAS among young children. In LMICs, little data were available for neonates and children and no data were available for pregnant women. Incidences of invasive GAS are likely to be underestimates, particularly in LMICs, due to low GAS surveillance. It is essential to improve available data to inform development of prevention and management strategies for invasive GAS. Wellcome Trust.