COVID-19 Publications


Apr, 2022

Screening and vaccination against COVID-19 to minimise school closure: a modelling study

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Authors: Colosi E, Bassignana G, Contreras DA, Poirier C, Boëlle PY, Cauchemez S, Yazdanpanah Y, Lina B, Fontanet A, Barrat A, Colizza V

Published in: The Lancet


Jan, 2022

Observed serial intervals of SARS-CoV-2 for the Omicron and Delta variants in Belgium based on contact tracing data, 19 November to 31 December 2021

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Authors: Kremer C, Braeye T, Proesmans K, André E, Torneri A, Hens N

Published in: MedRxiv


Sep, 2021

Early Impact of SARS-CoV-2 on Pediatric Clinical Research: A Pan-European and Canadian Snapshot in Time


Authors: O L. Mantha, F. Flamein, M. Turner, R. M. Fernandes, R. Hankard, the Network of National Networks Study Group

Published in: The Journal od Pediatrics



The article is meant to capture the early effects of the SARS-CoV-2 pandemic on pediatric clinical research.

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Aug, 2021

Pre-activated antiviral innate immunity in the upper airways controls early SARS-CoV-2 infection in children


Authors: J. Loske, J. Röhmel, S. Lukassen, S. Stricker, V. G. Magalhães, J. Liebig, R. L. Chua, L. Thürmann, M. Messingschlager, A. Seegebarth, B. Timmermann, S. Klages, M. Ralser, B. Sawitzki, L. E. Sander, V. M. Corman, C. Conrad, S. Laudi, M. Binder, S. Trump, R. Eils, M. A. Mall and I. Lehmann

Published in: Nature Biotechnology



Children have reduced severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection rates and a substantially lower risk for developing severe coronavirus disease 2019 compared with adults. However, the molecular mechanisms underlying protection in younger age groups remain unknown. Here we characterize the single-cell transcriptional landscape in the upper airways of SARS-CoV-2-negative (n = 18) and age-matched SARS-CoV-2-positive (n = 24) children and corresponding samples from adults (n = 44), covering an age range of 4 weeks to 77 years. Children displayed higher basal expression of relevant pattern recognition receptors such as MDA5 (IFIH1) and RIG-I (DDX58) in upper airway epithelial cells, macrophages and dendritic cells, resulting in stronger innate antiviral responses upon SARS-CoV-2 infection than in adults. We further detected distinct immune cell subpopulations including KLRC1 (NKG2A)+ cytotoxic T cells and a CD8+ T cell population with a memory phenotype occurring predominantly in children. Our study provides evidence that the airway immune cells of children are primed for virus sensing, resulting in a stronger early innate antiviral response to SARS-CoV-2 infection than in adults.

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Aug, 2021

Evaluation of mRNA-1273 SARS-CoV-2 Vaccine in Adolescents


Authors: K Ali, GBerman, H Zhou, W Deng, V Faughnan, M Coronado-Voges, B Ding, J Dooley, B Girard, W Hillebrand, R Pajon, JM. Miller, B Leav, and R McPhee

Published in: New England Journal of Medicine



Background The incidence of coronavirus disease 2019 (Covid-19) among adolescents between 12 and 17 years of age was approximately 900 per 100,000 population from April 1 through June 11, 2021. The safety, immunogenicity, and efficacy of the mRNA-1273 vaccine in adolescents are unknown.

Methods In this ongoing phase 2–3, placebo-controlled trial, we randomly assigned healthy adolescents (12 to 17 years of age) in a 2:1 ratio to receive two injections of the mRNA-1273 vaccine (100 μg in each) or placebo, administered 28 days apart. The primary objectives were evaluation of the safety of mRNA-1273 in adolescents and the noninferiority of the immune response in adolescents as compared with that in young adults (18 to 25 years of age) in a phase 3 trial. Secondary objectives included the efficacy of mRNA-1273 in preventing Covid-19 or asymptomatic severe acute respiratory syndrome coronavirus 2 infection.

Results A total of 3732 participants were randomly assigned to receive mRNA-1273 (2489 participants) or placebo (1243 participants). In the mRNA-1273 group, the most common solicited adverse reactions after the first or second injections were injection-site pain (in 93.1% and 92.4%, respectively), headache (in 44.6% and 70.2%, respectively), and fatigue (in 47.9% and 67.8%, respectively); in the placebo group, the most common solicited adverse reactions after the first or second injections were injection-site pain (in 34.8% or 30.3%, respectively), headache (in 38.5% and 30.2%, respectively), and fatigue (in 36.6% and 28.9%, respectively). No serious adverse events related to mRNA-1273 or placebo were noted. The geometric mean titer ratio of pseudovirus neutralizing antibody titers in adolescents relative to young adults was 1.08 (95% confidence interval [CI], 0.94 to 1.24), and the absolute difference in serologic response was 0.2 percentage points (95% CI, −1.8 to 2.4), which met the noninferiority criterion. No cases of Covid-19 with an onset of 14 days after the second injection were reported in the mRNA-1273 group, and four cases occurred in the placebo group.

Conclusions The mRNA-1273 vaccine had an acceptable safety profile in adolescents. The immune response was similar to that in young adults, and the vaccine was efficacious in preventing Covid-19. (Funded by Moderna and the Biomedical Advanced Research and Development Authority; Teen COVE number, NCT04649151. opens in new tab.)


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Aug, 2021

Illness duration and symptom profile in symptomatic UK school-aged children tested for SARS-CoV-2


Authors: E Molteni, CH Sudre, LS Canas, SS Bhopal, RC Hughes, M Antonelli, B Murray, K Kläser, E Kerfoot, L Chen, J Deng, C Hu, Somesh Selvachandran, Kenneth Read, Joan Capdevila Pujol, Prof Alexander Hammers, Prof Tim D Spector, Prof Sebastien Ourselin, Claire J Steves, Marc Modat, Michael Absoud, Prof Emma L Duncan

Published in: The Lancet



Background In children, SARS-CoV-2 infection is usually asymptomatic or causes a mild illness of short duration. Persistent illness has been reported; however, its prevalence and characteristics are unclear. We aimed to determine illness duration and characteristics in symptomatic UK school-aged children tested for SARS-CoV-2 using data from the COVID Symptom Study, one of the largest UK citizen participatory epidemiological studies to date.

Methods In this prospective cohort study, data from UK school-aged children (age 5–17 years) were reported by an adult proxy. Participants were voluntary, and used a mobile application (app) launched jointly by Zoe Limited and King’s College London. Illness duration and symptom prevalence, duration, and burden were analysed for children testing positive for SARS-CoV-2 for whom illness duration could be determined, and were assessed overall and for younger (age 5–11 years) and older (age 12–17 years) groups. Children with longer than 1 week between symptomatic reports on the app were excluded from analysis. Data from symptomatic children testing negative for SARS-CoV-2, matched 1:1 for age, gender, and week of testing, were also assessed.

Findings 258 790 children aged 5–17 years were reported by an adult proxy between March 24, 2020, and Feb 22, 2021, of whom 75 529 had valid test results for SARS-CoV-2. 1734 children (588 younger and 1146 older children) had a positive SARS-CoV-2 test result and calculable illness duration within the study timeframe (illness onset between Sept 1, 2021, and Jan 24, 2021). The most common symptoms were headache (1079 [62·2%] of 1734 children), and fatigue (954 [55·0%] of 1734 children). Median illness duration was 6 days (IQR 3–11) versus 3 days (2–7) in children testing negative, and was positively associated with age (Spearman’s rank-order rs 0·19, p<0·0001). Median illness duration was longer for older children (7 days, IQR 3–12) than younger children (5 days, 2–9). 77 (4·4%) of 1734 children had illness duration of at least 28 days, more commonly in older than younger children (59 [5·1%] of 1146 older children vs 18 [3·1%] of 588 younger children; p=0·046). The commonest symptoms experienced by these children during the first 4 weeks of illness were fatigue (65 [84·4%] of 77), headache (60 [77·9%] of 77), and anosmia (60 [77·9%] of 77); however, after day 28 the symptom burden was low (median 2 symptoms, IQR 1–4) compared with the first week of illness (median 6 symptoms, 4–8). Only 25 (1·8%) of 1379 children experienced symptoms for at least 56 days. Few children (15 children, 0·9%) in the negatively tested cohort had symptoms for at least 28 days; however, these children experienced greater symptom burden throughout their illness (9 symptoms, IQR 7·7–11·0 vs 8, 6–9) and after day 28 (5 symptoms, IQR 1·5–6·5 vs 2, 1–4) than did children who tested positive for SARS-CoV-2.

Interpretation Although COVID-19 in children is usually of short duration with low symptom burden, some children with COVID-19 experience prolonged illness duration. Reassuringly, symptom burden in these children did not increase with time, and most recovered by day 56. Some children who tested negative for SARS-CoV-2 also had persistent and burdensome illness. A holistic approach for all children with persistent illness during the pandemic is appropriate.


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Aug, 2021

Risk of infection and transmission of SARSCoV-2 among children and adolescents in households, communities and educational settings: A systematic review and meta-analysis


Authors: O Irfan, J Li, K Tang, Z Wang, ZA Bhuta

Published in: Journal of global health



Background There is uncertainty with respect to SARS-CoV-2 transmission in children (0-19 years) with controversy on effectiveness of school-closures in controlling the pandemic. It is of equal importance to evaluate the risk of transmission in children who are often asymptomatic or mildly symptomatic carriers that may incidentally transmit SARS-CoV-2 in different settings. We conducted this review to assess transmission and risks for SARS-CoV-2 in children (by age groups or grades) in community and educational-settings compared to adults.

Methods Data for the review were retrieved from PubMed, EMBASE, Cochrane Library, WHO COVID-19 Database, China National Knowledge Infrastructure (CNKI) Database, WanFang Database, Latin American and Caribbean Health Sciences Literature (LILACS), Google Scholar, and preprints from medRixv and bioRixv) covering a timeline from December 1, 2019 to April 1, 2021. Population-screening, contact-tracing and cohort studies reporting prevalence and transmission of SARS-CoV-2 in children were included. Data were extracted according to PRISMA guidelines. Meta-analyses were performed using Review Manager 5.3.

Results Ninety studies were included. Compared to adults, children showed comparable national (risk ratio (RR)=0.87, 95% confidence interval (CI)=0.71-1.060 and subnational (RR=0.81, 95% CI=0.66-1.01) prevalence in population-screening studies, and lower odds of infection in community/household contact-tracing studies (odds ratio (OR) =0.62, 95% CI=0.46-0.84). On disaggregation, adolescents observed comparable risk (OR=1.22, 95% CI=0.74-2.04) with adults. In educational-settings, children attending daycare/preschools (OR=0.53, 95% CI=0.38-0.72) were observed to be at lower-risk when compared to adults, with odds of infection among primary (OR=0.85, 95% CI=0.55-1.31) and high-schoolers (OR=1.30, 95% CI=0.71-2.38) comparable to adults. Overall, children and adolescents had lower odds of infection in educational-settings compared to community and household clusters.

Conclusions Children (<10 years) showed lower susceptibility to COVID-19 compared to adults, whereas adolescents in communities and high-schoolers had comparable risk. Risks of infection among children in educational-settings was lower than in communities. Evidence from school-based studies demonstrate it is largely safe for children (<10 years) to be at schools, however older children (10-19 years) might facilitate transmission. Despite this evidence, studies focusing on the effectiveness of mitigation measures in educational settings are urgently needed to support both public health and educational policy-making for school reopening.

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Aug, 2021

Evidence of lung perfusion defects and ongoing inflammation in an adolescent with post-acute sequelae of SARS-CoV-2 infection


Authors: D Buonsenso, DD Giuda, L Sigfrid, DA Pizzuto, GD Sante, CD Rose, I Lazzareschi, M Sali, F Baldi, DPR Chieffo, D Munblit, P Valentini

Published in: The Lancet



Although more patients are surviving COVID-19, there are emerging data on a substantial proportion of patients with persisting, and often debilitating, symptoms and sequelae for months following acute COVID-19. This scenario is commonly referred to as post-acute sequelae of SARS-CoV-2 infection (PASC) or long COVID. Some of the most commonly reported symptoms are fatigue, weakness, breathlessness, chest pain, and concentration impairment. Several independent studies have shown the existence of PASC, with chronic inflammation and chronic endothelial disease suggested among the possible pathophysiological mechanisms of this multifaceted condition. Although the course of acute SARS-CoV-2 infection in children is normally milder and can present with less typical symptoms compared with adults, emerging evidence from Sweden, Italy, the UK, and Russia suggests that children can also have persisting symptoms more than 3 months after acute COVID-19, with a similar pattern of symptoms as reported by adults. In light of an increasing number of parents and clinicians asking for guidance and support for children with PASC in our centre, we have set up a post-COVID Paediatric Unit. Children with a microbiologically confirmed diagnosis of COVID-19 are assessed in our post-COVID Paediatric Unit at least 5 weeks after the onset of acute infection (see the appendix for our post-COVID paediatric follow-up protocol).


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Aug, 2021

COVID-19 vaccines for children in LMICs: another equity issue


Authors: B Kampmann U Okomo

Published in: The Lancet



Given the success of COVID-19 vaccines in preventing death and severe disease in adults  and their impact on community transmission, use in children and young people (CYP) inevitably requires consideration. Although severe COVID-19 is rare in CYP, they are affected by SARS-CoV-2 infection and the impacts of the COVID-19 pandemic, including education, mental health, and general wellbeing.
As of late July, 2021, no COVID-19 vaccine is recommended for children younger than 12 years and safety and efficacy data from phase 3 clinical trials are so far limited: 1131 CYP aged 12–15 years received the Pfizer–BioNTech mRNA vaccine and safety data are available from phase 1 and 2 trials of Sinovac’s inactivated CoronaVac vaccine in 438 children aged 3–17 years.
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Jul, 2021

Performance of RT-PCR on Saliva Specimens Compared With Nasopharyngeal Swabs for the Detection of SARS-CoV-2 in Children: A Prospective Comparative Clinical Trial


Authors: Y Fougère, JM Schwob, A Miauton, F Hoegger, O Opota, K Jaton, R Brouillet, G Greub, B Genton, M Gehri, I Taddeo, V D’Acremont, SA Asner

Published in: The Pediatric Infectious Disease Journal



Background Saliva reverse transcriptase-Polymerase chain reaction (RT-PCR) is an attractive alternative for the detection of severe acute respiratory syndrome coronavirus 2 in adults with less known in children.

Methods Children with coronavirus disease 2019 symptoms were prospectively enrolled in a 1-month comparative clinical trial of saliva and nasopharyngeal (NP) RT-PCR. Detection rates and sensitivities of saliva and NP RT-PCR were compared as well as discordant NP and saliva RT-PCR findings including viral loads (VLs).

Results Of 405 patients enrolled, 397 patients had 2 tests performed. Mean age was 12.7 years (range, 1.2–17.9). Sensitivity of saliva was 85.2% (95% confidence interval: 78.2%–92.1%) when using NP as the standard; sensitivity of NP was 94.5% (89.8%–99.2%) when saliva was considered as the standard. For a NP RT-PCR VL threshold of ≥103 and ≥104 copies/mL, sensitivity of saliva increases to 88.7% and 95.2%, respectively. Sensitivity of saliva and NP swabs was, respectively, 89.5% and 95.3% in patient with symptoms less than 4 days (P = 0.249) and 70.0% and 95.0% in those with symptoms ≥4–7 days (P = 0.096). The 15 patients who had an isolated positive NP RT-PCR were younger (P = 0.034), had lower NP VL (median 5.6 × 103 vs. 3.9 × 107P < 0.001), and could not drool saliva at the end of the sampling (P = 0.002). VLs were lower with saliva than with NP RT-PCR (median 8.7 cp/mL × 104; interquartile range 1.2 × 104–5.2 × 105; vs. median 4.0 × 107 cp/mL; interquartile range, 8.6 × 105–1 × 108P < 0.001).

Conclusions While RT-PCR testing on saliva performed more poorly in younger children and likely after longer duration of symptoms, saliva remains an attractive alternative to NP swabs in children.

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