Background

Understanding community SARS-CoV-2 seroprevalence in children is vital in helping understand the epidemiology of the virus and informing COVID-19 public health policy.

Methods

An ongoing community-based repeat cross-sectional seroprevalence study recruited participants aged 0-24 year between October 2019 and August 2020 across 8 regions in England. Participants were predominantly recruited by mail-out to postcodes with Index of Material Deprivation (IMD) distribution representative of the region. Serum samples, demographics and symptom data were obtained, and samples processed analysed by Abbott nucleocapsid and a Public Health England in-house Receptor Binding Domain (RBD) assays to determine the presence of antibodies against SARS-CoV-2. Combined adjusted seroprevalence estimates were calculated incorporating both RBD or Abbott (sensitivity 96.9%, specificity 96.9%).

Results

Of the 1145 participants recruited, 54 (4.7%) were seropositive by Abbott and 56 (4.9%) by RBD. Between June and August 2020 adjusted seroprevalence in 0-4 year olds was 1% (N= 54, CI 0-8) compared with 12.6% (N=114, CI 6.3-20.4) in 20-24 year olds. A logistic regression analysis demonstrated Black and Minority Ethnic (BAME) participants had higher risk of SARS-CoV-2 infection than white participants (multivariate analysis OR 2.9, CI 1.28-6.57, p = 0.011). Risk was inversely related to deprivation (p = 0.003 across IMD quintiles, OR 0.16 for lowest compared to the highest IMD quintile). 16/34 antibody positive participants reported no flu-like symptoms.

Conclusions

A small but significant minority of children had evidence of infection, and this was higher in BAME participants, although co-morbid risk factors such as obesity and type 2 diabetes are less likely in this paediatric population compared with adult cohorts. Ongoing sampling through the second wave of COVID-19 in England, with enhanced BAME recruitment, will further interrogate this association.

Funded by National Institute for Health Research (NIHR)

Clinical Trial Registration

ClinicalTrials.gov Identifier: NCT04061382

Background

Pneumococcal conjugate vaccine (7 valent, PCV7) was first introduced in the UK in 2006 as a 2+1 (2, 4 and 12 months) schedule. A 13 valent vaccine (PCV13) replaced PCV7 in 2010. Recently the schedule changed to a 1+1 (3, 12 months) schedule for children born 1^st January 2020 onwards. We present baseline data from a cross-sectionalpneumococcal carriage study in 6-12 month olds in the Thames Valley region.

Methods

Nasopharyngeal swabs were taken from healthy 6-12 month olds in 2017/20 who had received a full primary course (two doses) of PCV13. A subset of participants provided a blood sample (finger or heel-prick). Molecular serotyping by microarray analysis was performed on ‘sweeps’ of selective culture plates from swabs with pneumococcal-presumptive growth, based on optochin susceptibility and bile solubility. Serum concentrations of total anti-capsular immunoglobulin G (IgG) for PCV13 serotypes were identified by luminescent microsphere.

Results

In total 615 children were swabbed, 274 (44.6%, 95% CI 40.6-48.6) of whom were carrying pneumococcus. PCV13 serotypes 3 (5, 0.8%), 19A(6, 1.0%), and 19F (3, 0.5%) were detected however, the majority (95.6%) of detected isolates (comprising >30 different serotypes) were non-vaccine types, most commonly 23B (34, 5.5%), 11A (31, 5.0%), 21 (31, 5.0%), 15B (28, 4.6%), and 10A (23, 3.7%).

A subset of 249 children provided a blood sample. Geometric mean antibody concentrations against PCV13 serotypes ranged from 0.26µg/ml (95% CI 0.22-0.31) (6B) to 2.31µg/ml (95% CI 2.08-2.56) (7F). The proportion of samples with IgG ≥0.35µg/ml ranged from 38.6% (23F) to 97.2% (7F).

Conclusions

Following a two-dose priming schedule there is a low prevalence of vaccine serotype carriage. These data provide an important baseline for comparison with carriage and seroprevalence data after a single priming dose.

Funded by Pfizer Ltd.

Clinical Trial Registration

Clinicaltrials.gov identifier NCT03102840

ClinicalTrials.gov Identifier: NCT01996007