QuantiFERON Gold-In-Tube for the diagnosis of mycobacterial tuberculosis infection in children under 5 years of age: A systematic review and meta-analysis.

BACKGROUND: Previous meta-analysis regarding the performance of QuantiFERON Gold-In-Tube in children have yielded contrasting results. Emerging data in children younger than 5 years of age necessitates a new analysis. METHODS: Systematic searches were conducted of MedLINE, EMBASE and Cochrane databases between 1998-2023. Pooled estimates of sensitivities and specificities of QFT-GIT compared to tuberculin skin test (TST) were calculated. The Kappa (k) coefficient was calculated for each study to determine the degree of congruence between TST and QFT-GIT results. Studies including patients co-infected with HIV or other immune compromising conditions or those treated with anti-tubercular treatment were excluded. RESULTS: Seventeen studies (4335 patients) were included in quantitative analysis. All studies were conducted in middle to high income countries. They were conducted across 14 countries and 4 studies in countries with high TB incidence. The pooled sensitivity, specificity and DOR were 0.45 (0.42-0.48), 0.96 (0.96-0.97) and 18.84 (7.33-48.41) respectively. The ability of QFT-GIT to discriminate with disease and no disease was "good" as demonstrated by a summary receiver operating characteristic curve with area under curve of 0.7812. The average Kappa (k) co-efficient was 0.501 with a wide variety of values between studies (0.167 to 0.800). CONCLUSION: The findings of this meta-analysis support the judicious use of QFT-GIT in children 5 years and under, with caution as a sole test to exclude Tuberculosis in this age group. The heterogeneity and methodological quality of diagnostic studies limits the generalisability of results.

Parent-Reported Child and Parent Quality of Life during COVID-19 Testing at an Australian Paediatric Hospital Outpatient Clinic: A Cross-Sectional Study.

Globally, we have seen a drop in adult and child quality of life (QOL) during the COVID-19 pandemic. However, little is known about adult or child QOL during the height of the pandemic in Australia and the impact of government-imposed restrictions, specifically attending school on-site versus home schooling. Our study aimed to establish if QOL in children and parents presenting to a Respiratory Infection Clinic in Victoria, Australia, for COVID-19 PCR testing differed from pre-pandemic population norms. We also explored whether on-site versus home schooling further impacted QOL. Following the child's test and prior to receiving results, consenting parents of children aged 6 to 17 years old completed the Child Health Utility 9 Dimension (CHU9D) instrument on their child's behalf. Parents of children aged birth to five years completed the EuroQOL 5-Dimension 5-Level (EQ-5D-5L) instrument on their own behalf (cross-sectional study). Data analyses utilised quantile regression, adjusting for the child's age, COVID-19 symptoms, gender and chronic health conditions. From July 2020 to November 2021, 2025 parents completed the CHU9D; the mean age for children was 8.41 years (±3.63 SD), and 48.4 per cent were female (n = 980/2025). In the same time period, 5751 parents completed the EQ-5D-5L; the mean age for children was 2.78 years (±1.74 SD), and 52.2 per cent were female (n = 3002/5751). Results showed that QOL scores were lower than pre-pandemic norms for 68 per cent of the CHU9D group and 60 per cent of the EQ-5D-5L group. Comparing periods of on-site to home schooling, there was no difference between the median QOL scores for both CHU9D (0.017, 95% CI -0.05 to 0.01) and EQ-5D-5L (0.000, 95% CI -0.002 to 0.002). Our large-scale study found that while QOL was reduced for children and parents at the point of COVID-19 testing during the pandemic, differing levels of government-imposed restrictions did not further impact QOL. These unique insights will inform decision-making in relation to COVID-19 and future pandemics.

A novel anterior nasal swab to detect respiratory viruses: a prospective study of diagnostic accuracy.

Detection of respiratory viruses requires testing of the upper respiratory tract to obtain specimens for analysis. However, nasal and throat swabs can cause discomfort and procedural anxiety in children. Respiratory sampling methods which are accurate and less invasive are needed. We aim to determine the positive and negative percentage agreement of a novel anterior nasal swab (ANS) compared with the combined throat and anterior nasal swab (CTN), the reference standard, for detection of respiratory viruses. Children 5 - 18 years of age presenting to a tertiary paediatric hospital with respiratory symptoms were tested with both swabs in randomised order. Respiratory samples were tested on a multiplex RT-PCR panel. Viral detections, RT-PCR cycle-threshold values and child/parent/clinician experience of the swab were recorded. There were 157 viral detections from 249 participant CTN swabs. In comparison with the CTN, the overall positive and negative percentage agreement of ANS for detection of respiratory viruses was 96.2% (95% CI, 91.8-98.3%) and 99.8% (95% CI, 99.6-99.9%), respectively. The ANS was "extremely comfortable", or only a "little uncomfortable" for 90% of children compared with 48% for CTN. 202 children (84%) rated the ANS as the preferred swab, and 208 (87%) indicated they would prefer ANS for future testing. The ANS required additional laboratory handling processes compared to the CTN. The ANS has high positive percentage agreement and is comparable to the current standard of care. The high acceptability from the less invasive ANS provides a more comfortable method for respiratory virus testing in children.Trial registrationClinicalTrials.gov ID NCT05043623.

Paediatric admissions with SARS-CoV-2 during the Delta and Omicron waves: an Australian single-centre retrospective study.

BACKGROUND: The clinical course of Australian children admitted to hospital with COVID-19 infection is not well understood, particularly over the Omicron period. METHODS: This study describes paediatric admissions to a single tertiary paediatric institution through the Delta and Omicron variant waves. All children admitted from 1 June 2021 to 30 September 2022 with a diagnosis of COVID-19 infection were included for analysis. RESULTS: 117 patients were admitted during the Delta wave compared with 737 during the Omicron wave. The median length of stay was 3.3 days (IQR 1.7-6.75.1) during Delta, compared with 2.1 days (IQR 1.1-4.53.4) during Omicron (p<0.01). 83 patients (9.7%) required intensive care unit (ICU) admission, a greater proportion during Delta (20, 17.1%) than Omicron (63, 8.6%, p<0.01). Patients admitted to the ICU were less likely to have received a dose of COVID-19 vaccination prior to admission than patients admitted to the ward (8, 24.2% vs 154, 45.8%, p=0.028). CONCLUSION: The Omicron wave resulted in an absolute increase in the number of children compared with Delta, but cases had lower severity, demonstrated by shorter length of stay and a smaller proportion of patients requiring intensive care. This is consistent with US and UK data describing a similar pattern.

Health of children who experienced Australian immigration detention.

BACKGROUND: Australian immigration policy resulted in large numbers of children being held in locked detention. We examined the physical and mental health of children and families who experienced immigration detention. METHODS: Retrospective audit of medical records of children exposed to immigration detention attending the Royal Children's Hospital Immigrant Health Service, Melbourne, Australia, from January 2012 -December 2021. We extracted data on demographics, detention duration and location, symptoms, physical and mental health diagnoses and care provided. RESULTS: 277 children had directly (n = 239) or indirectly via parents (n = 38) experienced locked detention, including 79 children in families detained on Nauru or Manus Island. Of 239 detained children, 31 were infants born in locked detention. Median duration of locked detention was 12 months (IQR 5-19 months). Children were detained on Nauru/Manus Island (n = 47/239) for a median of 51 (IQR 29-60) months compared to 7 (IQR 4-16) months for those held in Australia/Australian territories (n = 192/239). Overall, 60% (167/277) of children had a nutritional deficiency, and 75% (207/277) had a concern relating to development, including 10% (27/277) with autism spectrum disorder and 9% (26/277) with intellectual disability. 62% (171/277) children had mental health concerns, including anxiety, depression and behavioural disturbances and 54% (150/277) had parents with mental illness. Children and parents detained on Nauru had a significantly higher prevalence of all mental health concerns compared with those held in Australian detention centres. CONCLUSION: This study provides clinical evidence of adverse impacts of held detention on children's physical and mental health and wellbeing. Policymakers must recognise the consequences of detention, and avoid detaining children and families.

Stick with the nose Saliva rapid antigen testing is not a viable method for testing children under 5 years old.

AIM: Respiratory testing with rapid antigen tests (RATs) in children under 5 years of age may be uncomfortable and presents specific challenges to testing due to compliance and procedural distress. The aim of this study was to investigate sensitivity and feasibility of self-collected nasal and saliva RAT tests compared with a combined nose and throat (CTN) swab PCR in children under 5. METHODS: Children aged between 1 month and 5 years, with confirmed COVID-19 or who were a household contact within 7 days were included. A saliva RAT, nasal RAT and CTN swab were collected by the parent. SARS-CoV-2 cycle threshold (Ct) values for CTN tested by PCR were compared with saliva and nasal RAT results. Parent preference for method of sample was recorded. RESULTS: Forty-one children were recruited with median age of 1.5 (interquartile range 0.7-4.0) years. Only 22/41 (54%) of parents were able to successfully collect a saliva RAT from their child. Sensitivity of the nasal RAT and saliva RAT was 0.889 (95% confidence interval (CI) 0.739-0.969) and 0.158 (95% CI 0.034-0.396), respectively. Upper limit of nasal RAT detection by CTN Ct value was higher than saliva (36.05 vs. 27.29). While saliva RAT was rated most comfortable, nasal RAT was rated the preferred specimen by parents for future testing, due to saliva collection difficulties and time taken. CONCLUSIONS: Rapid antigen testing with nasal RAT is a more feasible and sensitive method for SARS-CoV-2 detection in young children compared with saliva RAT.

Comparison of antibody responses to SARS-CoV-2 variants in Australian children.

There is limited understanding of antibody responses in children across different SARS-CoV-2 variants. As part of an ongoing household cohort study, we assessed the antibody response among unvaccinated children infected with Wuhan, Delta, or Omicron variants, as well as vaccinated children with breakthrough Omicron infection, using a SARS-CoV-2 S1-specific IgG assay and surrogate virus neutralization test (% inhibition). Most children infected with Delta (100%, 35/35) or Omicron (81.3%, 13/16) variants seroconverted by one month following infection. In contrast, 37.5% (21/56) children infected with Wuhan seroconverted, as previously reported. However, Omicron-infected children (geometric mean concentration 46.4 binding antibody units/ml; % inhibition = 16.3%) mounted a significantly lower antibody response than Delta (435.5 binding antibody untis/mL, % inhibition = 76.9%) or Wuhan (359.0 binding antibody units/mL, % inhibition = 74.0%). Vaccinated children with breakthrough Omicron infection mounted the highest antibody response (2856 binding antibody units/mL, % inhibition = 96.5%). Our findings suggest that despite a high seropositivity rate, Omicron infection in children results in lower antibody levels and function compared with Wuhan or Delta infection or with vaccinated children with breakthrough Omicron infection. Our data have important implications for public health measures and vaccination strategies to protect children.

Management of tuberculosis infection in Victorian children: A retrospective clinical audit of factors affecting treatment completion.

BACKGROUND: Tuberculosis preventive treatment (TPT) is strongly recommended for children following infection with Mycobacterium tuberculosis because of their high risk of progression to active tuberculosis, including severe disseminated disease. We describe the implementation of TPT for children and adolescents with evidence of tuberculosis infection (TBI) at Victoria's largest children's hospital and examine factors affecting treatment completion. METHODS: We conducted a retrospective clinical audit of all children and adolescents aged <18 years diagnosed with latent TBI at the Royal Children's Hospital, Melbourne, between 2010 and 2016 inclusive. The primary outcome was treatment completion, defined as completing TPT to within one month of a target duration for the specified regimen (for instance, at least five months of a six-month isoniazid course), confirmed by the treating clinician. Factors associated with treatment adherence were evaluated by univariate and multivariate analysis. RESULTS: Of 402 participants with TBI, 296 (74%) met the criteria for treatment "complete". The most common TPT regimen was six months of daily isoniazid (377, 94%). On multivariate logistic regression analysis, treatment completion was more likely among children and adolescents who had refugee health screening performed (OR 2.31, 95%CI 1.34-4.00) or who were also treated for other medical conditions (OR 1.67 95%CI 1.0-2.85), and less likely among those who experienced side-effects (OR 0.32, 95%CI 0.11-0.94). However, TPT was generally well tolerated with side-effects reported in 15 participants (3.7%). CONCLUSION: Identification of factors associated with TPT completion and deficiencies in the existing care pathway have informed service provision changes to further improve outcomes for Victorian children and adolescents with TBI.

Virology and immune dynamics reveal high household transmission of ancestral SARS-CoV-2 strain.

BACKGROUND: Household studies are crucial for understanding the transmission of SARS-CoV-2 infection, which may be underestimated from PCR testing of respiratory samples alone. We aim to combine the assessment of household mitigation measures; nasopharyngeal, saliva, and stool PCR testing; along with mucosal and systemic SARS-CoV-2-specific antibodies, to comprehensively characterize SARS-CoV-2 infection and transmission in households. METHODS: Between March and September 2020, we obtained samples from 92 participants in 26 households in Melbourne, Australia, in a 4-week period following the onset of infection with ancestral SARS-CoV-2 variants. RESULTS: The secondary attack rate was 36% (24/66) when using nasopharyngeal swab (NPS) PCR positivity alone. However, when respiratory and nonrespiratory samples were combined with antibody responses in blood and saliva, the secondary attack rate was 76% (50/66). SARS-CoV-2 viral load of the index case and household isolation measures were key factors that determine secondary transmission. In 27% (7/26) of households, all family members tested positive by NPS for SARS-CoV-2 and were characterized by lower respiratory Ct values than low transmission families (Median 22.62 vs. 32.91; IQR 17.06-28.67 vs. 30.37-34.24). High transmission families were associated with enhanced plasma antibody responses to multiple SARS-CoV-2 antigens and the presence of neutralizing antibodies. Three distinguishing saliva SARS-CoV-2 antibody features were identified according to age (IgA1 to Spike 1, IgA1 to nucleocapsid protein (NP)), suggesting that adults and children generate distinct mucosal antibody responses during the acute phase of infection. CONCLUSION: Utilizing respiratory and nonrespiratory PCR testing, along with the measurement of SARS-CoV-2-specific local and systemic antibodies, provides a more accurate assessment of infection within households and highlights some of the immunological differences in response between children and adults.

Influenza vaccine administration in a paediatric intensive care unit.

AIM: We describe the clinical profile of children and outcomes of influenza immunisation for patients in a paediatric intensive care unit (PICU). METHODS: Over two influenza seasons: 19/04/2018 to 07/08/2018 and 02/05/2019 to 10/10/2019, an immunisation nurse and PICU nurse coordinator met weekly and identified patients to receive the influenza vaccine. An inpatient list of PICU patients was screened for eligible patients: greater than 6 months of age, did not have imminent procedures (e.g. surgery) or were not critically unwell, as determined by the treating team, to receive the influenza vaccine. Patients were excluded if they had undergone surgery in the previous 24 hours or were being treated palliatively. RESULTS: Sixty patients in PICU were identified, with 43% (26/60) receiving the vaccine while in PICU and 17% (10/60) once discharged from PICU to the general ward environment. The majority of patients immunised were in PICU due to cardiac surgery/cardiology or general medical conditions, such as cerebral palsy or RSV bronchiolitis. There were no reported adverse events following immunisation. CONCLUSIONS: We have demonstrated the suitability and acceptability of children in the PICU receiving the seasonal influenza vaccine and tailored interventions to follow-up once discharged from PICU to optimise protection.

SARS-CoV-2-specific T cell memory with common TCRαß motifs is established in unvaccinated children who seroconvert after infection.

As the establishment of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific T cell memory in children remains largely unexplored, we recruited convalescent COVID-19 children and adults to define their circulating memory SARS-CoV-2-specific CD4+ and CD8+ T cells prior to vaccination. We analyzed epitope-specific T cells directly ex vivo using seven HLA class I and class II tetramers presenting SARS-CoV-2 epitopes, together with Spike-specific B cells. Unvaccinated children who seroconverted had comparable Spike-specific but lower ORF1a- and N-specific memory T cell responses compared with adults. This agreed with our TCR sequencing data showing reduced clonal expansion in children. A strong stem cell memory phenotype and common T cell receptor motifs were detected within tetramer-specific T cells in seroconverted children. Conversely, children who did not seroconvert had tetramer-specific T cells of predominantly naive phenotypes and diverse TCRαß repertoires. Our study demonstrates the generation of SARS-CoV-2-specific T cell memory with common TCRαß motifs in unvaccinated seroconverted children after their first virus encounter.

Comparison of Seroconversion in Children and Adults With Mild COVID-19.

Importance: The immune response in children with SARS-CoV-2 infection is not well understood. Objective: To compare seroconversion in nonhospitalized children and adults with mild SARS-CoV-2 infection and identify factors that are associated with seroconversion. Design, Setting, and Participants: This household cohort study of SARS-CoV-2 infection collected weekly nasopharyngeal and throat swabs and blood samples during the acute (median, 7 days for children and 12 days for adults [IQR, 4-13] days) and convalescent (median, 41 [IQR, 31-49] days) periods after polymerase chain reaction (PCR) diagnosis for analysis. Participants were recruited at The Royal Children's Hospital, Melbourne, Australia, from May 10 to October 28, 2020. Participants included patients who had a SARS-CoV-2-positive nasopharyngeal or oropharyngeal swab specimen using PCR analysis. Main Outcomes and Measures: SARS-CoV-2 immunoglobulin G (IgG) and cellular (T cell and B cell) responses in children and adults. Seroconversion was defined by seropositivity in all 3 (an in-house enzyme-linked immunosorbent assay [ELISA] and 2 commercial assays: a SARS-CoV-2 S1/S2 IgG assay and a SARS-CoV-2 antibody ELISA) serological assays. Results: Among 108 participants with SARS-CoV-2-positive PCR findings, 57 were children (35 boys [61.4%]; median age, 4 [IQR, 2-10] years) and 51 were adults (28 women [54.9%]; median age, 37 [IQR, 34-45] years). Using the 3 established serological assays, a lower proportion of children had seroconversion to IgG compared with adults (20 of 54 [37.0%] vs 32 of 42 [76.2%]; P < .001). This result was not associated with viral load, which was similar in children and adults (mean [SD] cycle threshold [Ct] value, 28.58 [6.83] vs 24.14 [8.47]; P = .09). In addition, age and sex were not associated with seroconversion within children (median age, 4 [IQR, 2-14] years for both seropositive and seronegative groups; seroconversion by sex, 10 of 21 girls [47.6%] vs 10 of 33 boys [30.3%]) or adults (median ages, 37 years for seropositive and 40 years for seronegative adults [IQR, 34-39 years]; seroconversion by sex, 18 of 24 women [75.0%] vs 14 of 18 men [77.8%]) (P > .05 for all comparisons between seronegative and seropositive groups). Symptomatic adults had 3-fold higher SARS-CoV-2 IgG levels than asymptomatic adults (median, 227.5 [IQR, 133.7-521.6] vs 75.3 [IQR, 36.9-113.6] IU/mL), whereas no differences were observed in children regardless of symptoms. Moreover, differences in cellular immune responses were observed in adults compared with children with seroconversion. Conclusions and Relevance: The findings of this cohort study suggest that among patients with mild COVID-19, children may be less likely to have seroconversion than adults despite similar viral loads. This finding has implications for future protection after SARS-CoV-2 infection in children and for interpretation of serosurveys that involve children. Further research to understand why seroconversion and development of symptoms are potentially less likely in children after SARS-CoV-2 infection and to compare vaccine responses may be of clinical and scientific importance.

Quality of care for children with acute respiratory infections in health facilities: a comparative analysis of assessment tools.

Background: Severe childhood pneumonia requires treatment in hospital by trained health care workers. It is therefore important to determine if health facilities provide quality health services for children with acute respiratory infections (ARI), including pneumonia. Using established indicators from WHO to measure quality of care (QoC) as a reference standard, this review aims to evaluate how well existing tools assess QoC for children presenting to health facilities with ARI. Methods: Existing assessment tools identified from a published systematic literature review that evaluated QoC assessment tools for children (<15 years) in health facilities for all health conditions were included in this ARI-specific review. 27 ARI-specific indicators or "quality measures" from the WHO "Standards for improving quality of care for children and young adolescents in health facilities" were selected for use as a reference standard to assess QoC for children presenting to health facilities with ARI symptoms. Each included assessment tool was evaluated independently by two paediatricians to determine how many of the WHO ARI quality measures were assessable by the tool. The assessment tools were then ranked in order of percentage of ARI quality measures assessable. Results: Nine assessment tools that assessed QoC for children attending health facilities were included. Two hospital care tools developed by WHO had the most consistency with ARI-specific indicators, assessing 22/27 (81.5%) and 20/27 (74.1%) of the quality measures. The remaining tools were less consistent with the ARI-specific indicators, including between zero to 16 of the 27 quality measures. The most common indicators absent from the tools were assessment of appropriate use of pulse oximetry and administration of oxygen, how often oxygen supply was unavailable, and mortality rates. Conclusions: The existing WHO hospital-based QoC assessment tools are comprehensive but could be enhanced by improved data quality around oxygen availability and appropriate use of pulse oximetry and oxygen administration. Any tools, however, should be considered within broader assessments of QoC, rather than utilised in isolation. Further adaptation to local settings will improve feasibility and facilitate progress in the delivery of quality health care for children with ARI. Registration: The protocol of the original systematic review was registered in PROSPERO ID: CRD42020175652.

The use of dried blood spots for the serological evaluation of SARS-CoV-2 antibodies.

BACKGROUND: To determine if dried blood spot specimens (DBS) can reliably detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies, we compared the SARS-CoV-2 IgG antibody response in paired serum and eluates from DBS specimens. METHODS: A total of 95 paired DBS and serum samples were collected from 74 participants (aged 1-63 years) as part of a household cohort study in Melbourne, Australia. SARS-CoV-2 IgG antibodies specific for the receptor-binding domain (RBD) and S1 proteins between serum and eluates from DBS specimens were compared using an FDA-approved ELISA method. RESULTS: Among the 74 participants, 42% (31/74) were children and the rest were adults. A total of 16 children and 13 adults were SARS-CoV-2 positive by polymerase chain reaction. The IgG seropositivity rate was similar between serum and DBS specimens (18.9% (18/95) versus 16.8% (16/95)), respectively. Similar RBD and S1-specific IgG levels were detected between serum and DBS specimens. Serum IgG levels strongly correlated with DBS IgG levels (r = 0.99, P < 0.0001) for both SARS-CoV-2 proteins. Furthermore, antibodies remained stable in DBS specimens for >3 months. CONCLUSIONS: DBS specimens can be reliably used as an alternative to serum samples for SARS-CoV-2 antibody measurement. The use of DBS specimens would facilitate serosurveillance efforts particularly in hard-to-reach populations and inform public health responses including COVID-19 vaccination strategies.

Characteristics and outcomes of SARS-CoV-2 infection in Victorian children at a tertiary paediatric hospital.

AIM: Victoria experienced two 'waves' of COVID-19 between March and September 2020 and more cases than any other jurisdiction in Australia. Although world-wide reports of COVID-19 reflect that children are less likely to experience severe disease compared with adults, hospitalisations and deaths have been reported. We report testing and outcomes of children with SARS-CoV-2 infection presenting to a tertiary paediatric hospital in Melbourne. METHODS: We conducted a prospective cohort study at The Royal Children's Hospital (RCH), including all children and adolescents (aged 0-18 years) who presented and were tested for SARS-CoV-2 over a 6-month period, between 21 March 2020, up to the 21 September 2020. Detailed epidemiological and clinical data were recorded. RESULTS: A total of 19 708 tests for SARS-CoV-2 were performed in 14 419 patients. One hundred and eighty patients tested positive for SARS-CoV-2 (1.2%). 110 (61%) were symptomatic, 60 (33%) were asymptomatic and 10 (6%) were pre-symptomatic. Close contacts of a positive case were associated with a higher risk of a testing positive for SARS-CoV-2 (120/2027 (6%) vs. 60/14589 (0.4%), RD 5.5 (95% CI 4.5 to 6.5), P < 0.001). Eighteen (10%) SARS-CoV-2-positive patients were admitted to hospital with one patient requiring intensive care. All patients recovered fully with no deaths. CONCLUSION: In Victorian children presenting to a tertiary hospital, SARS-CoV-2 infection caused predominantly mild or asymptomatic infection, with most children not requiring hospitalisation.

COVID-19 in children. II: Pathogenesis, disease spectrum and management.

The global disruption of the COVID-19 pandemic has impacted the life of every child either directly or indirectly. This review explores the pathophysiology, immune response, clinical presentation and treatment of COVID-19 in children, summarising the most up-to-date data including recent developments regarding variants of concern. The acute infection with SARS-CoV-2 is generally mild in children, whilst the post-infectious manifestations, including paediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2 (PIMS-TS) and 'long COVID' in children, are more complex. Given that most research on COVID-19 has focused on adult cohorts and that clinical manifestations, treatment availability and impacts differ markedly in children, research that specifically examines COVID-19 in children needs to be prioritised.

COVID-19 in children: I. Epidemiology, prevention and indirect impacts.

Children globally have been profoundly impacted by the coronavirus disease 2019 (COVID-19) pandemic. This review explores the direct and indirect public health impacts of COVID-19 on children. We discuss in detail the transmission dynamics, vaccination strategies and, importantly, the 'shadow pandemic', encompassing underappreciated indirect impacts of the pandemic on children. The indirect effects of COVID-19 will have a long-term impact beyond the immediate pandemic period. These include the mental health and wellbeing risks, disruption to family income and attendant stressors including increased family violence, delayed medical attention and the critical issue of prolonged loss of face-to-face learning in a normal school environment. Amplification of existing inequities and creation of new disadvantage are likely additional sequelae, with children from vulnerable families disproportionately affected. We emphasise the responsibility of paediatricians to advocate on behalf of this vulnerable group to ensure the longer-term effects of COVID-19 public health responses on the health and wellbeing of children are fully considered.

Children and Adults in a Household Cohort Study Have Robust Longitudinal Immune Responses Following SARS-CoV-2 Infection or Exposure.

Children have reduced severity of COVID-19 compared to adults and typically have mild or asymptomatic disease. The immunological mechanisms underlying these age-related differences in clinical outcomes remain unexplained. Here, we quantify 23 immune cell populations in 141 samples from children and adults with mild COVID-19 and their PCR-negative close household contacts at acute and convalescent time points. Children with COVID-19 displayed marked reductions in myeloid cells during infection, most prominent in children under the age of five. Recovery from infection in both children and adults was characterised by the generation of CD8 TCM and CD4 TCM up to 9 weeks post infection. SARS-CoV-2-exposed close contacts also had immunological changes over time despite no evidence of confirmed SARS-CoV-2 infection on PCR testing. This included an increase in low-density neutrophils during convalescence in both exposed children and adults, as well as increases in CD8 TCM and CD4 TCM in exposed adults. In comparison to children with other common respiratory viral infections, those with COVID-19 had a greater change in innate and T cell-mediated immune responses over time. These findings provide new mechanistic insights into the immune response during and after recovery from COVID-19 in both children and adults.

Prospective characterisation of SARS-CoV-2 infections among children presenting to tertiary paediatric hospitals across Australia in 2020: a national cohort study.

OBJECTIVE: To present Australia-wide data on paediatric COVID-19 and multisystem inflammatory syndromes to inform health service provision and vaccination prioritisation. DESIGN: Prospective, multicentre cohort study. SETTING: Eight tertiary paediatric hospitals across six Australian states and territories in an established research surveillance network-Paediatric Active Enhanced Disease (PAEDS). PARTICIPANTS: All children aged <19 years with SARS-CoV-2 infection including COVID-19, Paediatric Inflammatory Multisystem Syndrome Temporally Associated with SARS-CoV-2 (PIMS-TS) and Kawasaki-like disease TS infection (KD-TS) treated at a PAEDS site from 24 March 2020 to 31 December 2020. INTERVENTION: Laboratory-confirmed SARS-CoV-2 infection. MAIN OUTCOME: Incidence of severe disease among children with COVID-19, PIMS-TS and KD-TS. We also compared KD epidemiology before and during the COVID-19 pandemic. RESULTS: Among 386 children with SARS-CoV-2 infection, 381 (98.7%) had COVID-19 (median 6.3 years (IQR 2.1-12.8),53.3% male) and 5 (1.3%) had multisystem inflammatory syndromes (PIMS-TS, n=4; KD-TS, n=1) (median 7.9 years (IQR 7.8-9.8)). Most children with COVID-19 (n=278; 73%) were Australian-born from jurisdictions with highest community transmission. Comorbidities were present in 72 (18.9%); cardiac and respiratory comorbidities were most common (n=32/72;44%). 37 (9.7%) children with COVID-19 were hospitalised, and two (0.5%) required intensive care. Postinfective inflammatory syndromes (PIMS-TS/KD-TS) were uncommon (n=5; 1.3%), all were hospitalised and three (3/5; 60%) required intensive care management. All children recovered and there were no deaths. KD incidence remained stable during the pandemic compared with prepandemic. CONCLUSIONS: Most children with COVID-19 had mild disease. Severe disease was less frequent than reported in high prevalence settings. Preventative strategies, such as vaccination, including children and adolescents, could reduce both the acute and postinfective manifestations of the disease.