Reassurance of population immunity to diphtheria in England: Results from a 2021 national serosurvey.

BACKGROUND: Diphtheria is rare in England because of an effective national immunisation schedule that includes 5 doses of a diphtheria-containing vaccine at 2, 3, 4 months, preschool and adolescent boosters. However, in recent years there has been a notable increase in cases due to Corynebacterium ulcerans among older adults and evidence of endemic transmission of C. diphtheriae (normally associated with travel to endemic countries). We aimed to update 2009 estimates of diphtheria immunity considering the evolving epidemiology. METHODS: Residual sera collected from diagnostic laboratories and general practitioners in England in 2021 were randomly selected and tested for diphtheria antibody, to estimate proportions protected per age group. Diphtheria antibody levels were defined as susceptible (<0.01 IU/mL), basic protection (0.01-0.099 IU/mL) and full protection (≥0.1 IU/mL). Immunity estimates were standardised to the England population and compared to 2009. RESULTS: Based on 3,745 residual sera tested, 89% (95%CI: 87%-90%) of the 2021 England population had at least basic diphtheria protection (vs. 90% [88%-92%] in 2009) and 50% (48%-52%) full protection (vs. 41% [38%-44%]). Higher antibody levels were observed in those aged 1 and under, 10-11, 12-15, 25-34 and 35-44 years compared to 2009. The largest proportion susceptible were observed in those aged 70+, 26% (21%-31%) vs 12% (7%-18%) in 2009. CONCLUSIONS: Basic diphtheria protection is comparable between 2021 and 2009. The increase in immunity in working age adults is likely due to the school leaver booster introduced in 1994. The current vaccination schedule is maintaining sufficient population immunity. However, we recommend clinicians remain vigilant to severe diphtheria outcomes in older adults, because of their observed susceptibility.

Monkeypox virus-infected individuals mount comparable humoral immune responses as Smallpox-vaccinated individuals.

In early 2022, a cluster of monkeypox virus (MPXV) infection (mpox) cases were identified within the UK with no prior travel history to MPXV-endemic regions. Subsequently, case numbers exceeding 80,000 were reported worldwide, primarily affecting gay, bisexual, and other men who have sex with men (GBMSM). Public health agencies worldwide have offered the IMVANEX Smallpox vaccination to these individuals at high-risk to provide protection and limit the spread of MPXV. We have developed a comprehensive array of ELISAs to study poxvirus-induced antibodies, utilising 24 MPXV and 3 Vaccinia virus (VACV) recombinant antigens. Panels of serum samples from individuals with differing Smallpox-vaccine doses and those with prior MPXV infection were tested on these assays, where we observed that one dose of Smallpox vaccination induces a low number of antibodies to a limited number of MPXV antigens but increasing with further vaccination doses. MPXV infection induced similar antibody responses to diverse poxvirus antigens observed in Smallpox-vaccinated individuals. We identify MPXV A27 as a serological marker of MPXV-infection, whilst MPXV M1 (VACV L1) is likely IMVANEX-specific. Here, we demonstrate analogous humoral antigen recognition between both MPXV-infected or Smallpox-vaccinated individuals, with binding to diverse yet core set of poxvirus antigens, providing opportunities for future vaccine (e.g., mRNA) and therapeutic (e.g., mAbs) design.

Sociodemographic disparities in COVID-19 seroprevalence across England in the Oxford RCGP primary care sentinel network.

OBJECTIVES: To monitor changes in seroprevalence of SARS-CoV-2 antibodies in populations over time and between different demographic groups. METHODS: A subset of practices in the Oxford-Royal College of General Practitioners (RCGP) Research and Surveillance Centre (RSC) sentinel network provided serum samples, collected when volunteer patients had routine blood tests. We tested these samples for SARS-CoV-2 antibodies using Abbott (Chicago, USA), Roche (Basel, Switzerland) and/or Euroimmun (Luebeck, Germany) assays, and linked the results to the patients' primary care computerised medical records. We report seropositivity by region and age group, and additionally examined the effects of gender, ethnicity, deprivation, rurality, shielding recommendation and smoking status. RESULTS: We estimated seropositivity from patients aged 18-100 years old, which ranged from 4.1% (95% CI 3.1-5.3%) to 8.9% (95% CI 7.8-10.2%) across the different assays and time periods. We found higher Euroimmun seropositivity in younger age groups, people of Black and Asian ethnicity (compared to white), major conurbations, and non-smokers. We did not observe any significant effect by region, gender, deprivation, or shielding recommendation. CONCLUSIONS: Our results suggest that prior to the vaccination programme, most of the population remained unexposed to SARS-CoV-2.