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Background: Hybrid immunity to SARS-CoV-2, resulting from both vaccination and natural infection, remains insufficiently understood in paediatric populations, despite increasing rates of breakthrough infections among vaccinated children., Methods: We conducted a prospective longitudinal study to investigate the magnitude, specificity, and cytokine profile of antigen-specific T cell responses elicited by breakthrough SARS-CoV-2 infection in a cohort of mRNA-vaccinated children (n = 29) aged 5-11. This longitudinal analysis involved six distinct time points spanning a 16-month period post-vaccination, during which we analysed a total of 159 blood samples. All children who were followed for at least 12 months (n = 26) experienced a breakthrough infection. We conducted cytokine release assays using minimal blood samples, and we verified the cellular origin of these responses through intracellular cytokine staining., Findings: After breakthrough infection, children who had received mRNA vaccines showed enhanced Th1 responses specific to Spike peptides. Additionally, their Spike-specific T cells exhibited a distinctive enrichment of CD4+ IFN-γ+IL10+ cells, a characteristic akin to adults with hybrid immunity. Importantly, vaccination did not impede the development of multi-specific T cell responses targeting Membrane, Nucleoprotein, and ORF3a/7/8 antigens., Interpretation: Children, previously primed with a Spike-based mRNA vaccine and experiencing either symptomatic or asymptomatic breakthrough infection, retained the ability to enhance and diversify Th1/IL-10 antigen-specific T cell responses against multiple SARS-CoV-2 proteins. These findings mirror characteristics associated with hybrid cellular immunity in adults, known to confer resistance against severe COVID-19., Funding: This study was funded by the National Medical Research Council (NMRC) Singapore (COVID19RF-0019, MOH-000019, MOH-000535, OFLCG19May-0034 and MOH-OFYIRG19nov-0002)., Competing Interests: Declaration of interests MQ: none; SH: none; SKH: none; JZ: none; CWT: none; CYC: none; JGL: none; LW: none; AB and NLB: report a pending patent for a method to monitor virus-specific T cells in biological samples and are co-founders of T Cell Diagnostic (TCD) Ltd., a biotech company developing T cell diagnostic for viral infections. CFY: reports honoraria and funding to attend conferences from Sanofi, Pfizer and Takeda., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Importance: Literature on vaccine effectiveness of SARS-CoV-2 messenger RNA (mRNA) vaccines for children younger than 5 years is limited., Objective: To report the effectiveness of monovalent mRNA vaccines against SARS-CoV-2 infection among Singaporean children aged 1 through 4 years during a COVID-19 pandemic wave of the Omicron XBB variant., Design, Setting, and Participants: This was a population-based cohort study, conducted over a 6-month study period from October 1, 2022, through March 31, 2023, after the implementation of community vaccination among all Singaporean children aged 1 through 4 years. The study period was dominated by the Omicron XBB subvariant., Exposure: Receipt of SARS-CoV-2 mRNA vaccines., Main Outcome Measure: Vaccine effectiveness against confirmed SARS-CoV-2 infection. The adjusted incidence rate ratio for confirmed infections using Poisson regression was reported, with the reference group being those who were unvaccinated. Analyses were stratified by prior documented SARS-CoV-2 infection., Results: A total of 121 628 children (median [IQR] age, 3.1 [2.2-3.9] years; 61 925 male [50.9%]) were included in the study, contributing 21 015 956 person-days of observation. The majority of children (11 294 of 11 705 [96.5%]) received the mRNA-1273 COVID-19 vaccine (Moderna). Vaccine effectiveness against confirmed infection was 45.2% (95% CI, 24.7%-60.2%) in partially vaccinated, infection-naive children and 63.3% (95% CI, 40.6%-77.3%) in fully vaccinated, infection-naive children compared with the unvaccinated group. Among previously infected children, vaccine effectiveness against reinfections in those with at least 1 vaccine dose was estimated at 74.6% (95% CI, 38.7%-89.5%)., Conclusions and Relevance: Study results suggest that completion of a primary mRNA vaccine series provided protection against SARS-CoV-2 infection in children aged 1 through 4 years. Although incidence of hospitalization and severe illness is low in this age group, there is potential benefit of vaccination in preventing infection and potential sequelae.

Importance: Infants younger than 6 months are at risk of severe SARS-CoV-2 infection. Data are lacking on the optimum timing for maternal vaccination and estimated effectiveness against Omicron variants, including XBB, for infants., Objective: To investigate maternal vaccination against Omicron variants, including XBB, and the association of vaccination timing during pregnancy vs prior to pregnancy and risks of SARS-CoV-2 infection among infants aged 6 months or younger., Design, Setting, and Participants: This population-based cohort study was conducted between January 1, 2022, and March 31, 2023. Singapore's national dataset was used to study infants born at greater than 32 weeks' gestation between January 1, 2022, and September 30, 2022. The study included infants whose parents had a confirmed SARS-CoV-2 infection from the date of birth up to 6 months of age. Of 21 609 infants born during this period, 7292 (33.7%) had at least 1 parent infected with SARS-CoV-2 before the age of 7 months. Statistical analysis was performed from April to July 2023., Exposure: Infants' mothers were unvaccinated, vaccinated prior to pregnancy, or vaccinated with a messenger RNA (mRNA) SARS-CoV-2 vaccine during pregnancy., Main Outcome and Measure: Infants were considered infected if they had a positive polymerase chain reaction test., Results: Among 7292 infants included in this study, 4522 (62.0%) had mothers who were Chinese, 527 (7.2%) had mothers who were Indian, 2007 (27.5%) had mothers who were Malay, and 236 (3.2%) had mothers who were other ethnicity; 6809 infants (93.4%) were born at full term, and 1272 infants (17.4%) were infected during the study period. There were 7120 infants (97.6%) born to mothers who had been fully vaccinated or boosted as of 14 days prior to delivery. The crude incidence rate was 174.3 per 100 000 person-days among infants born to mothers who were unvaccinated, 122.2 per 100 000 person-days among infants born to mothers who were vaccinated before pregnancy, and 128.5 per 100 000 person-days among infants born to mothers who were vaccinated during pregnancy. The estimated vaccine effectiveness (VE) was 41.5% (95% CI, 22.8% to 55.7%) among infants born to mothers vaccinated during pregnancy. Infants of mothers who received vaccination prior to pregnancy did not have a lower risk for infection (estimated VE, 15.4% [95% CI, -17.6% to 39.1%]). A lower risk for Omicron XBB infection was only observed among mothers vaccinated with the third (booster) dose antenatally (estimated VE, 76.7% [95% CI, 12.8% to 93.8%])., Conclusions and Relevance: In this population-based cohort study, maternal mRNA vaccination was associated with a lower risk of Omicron SARS-CoV-2 infection among infants up to 6 months of age only if the vaccine was given during the antenatal period. These findings suggest that mRNA vaccination during pregnancy may be needed for lower risk of SARS-CoV-2 infection among newborns.

Introduction: Information on the quality of health of children and younger persons (CYPs) after SARS-COV-2 infection remains scarce, especially from Asia. In this study, we utilised an online survey to investigate Long COVID prevalence in CYPs in Singapore., Method: The study was an anonymised online survey of physical and functional symptoms, made available from 14 October 2022 to 15 January 2023. Caregivers of CYPs aged 0 to 18 years were invited to complete the survey on behalf of their CYPs. Participants provided demographic information and their history of SARS-CoV-2 infection status to allow classification into cases and controls for analysis., Results: A total of 640 completed responses were analysed, 471 (73.6%) were cases and 169 (26.4%) were controls. The prevalence of Long COVID ≥3 months post-infection was 16.8%. This decreased to 8.7% ≥6 months post-infection. Cases had higher odds of developing Long COVID (odds ratio [OR] 2.42, 95% confidence interval [CI] 1.31-4.74). The most common symptoms of Long COVID were persistent cough (7.4%), nasal congestion (7.6%) and fatigue (3.0%). Male gender was significantly associated with higher odds of Long COVID (adjusted OR 1.71 [1.04-2.83]). Vaccinated CYPs had lower odds of Long COVID but this was not statically significant (adjusted OR 0.65, 95% CI 0.34-1.25)., Conclusion: About 1 in 6 CYPs in Singapore developed Long COVID with persistence of 1 or more symptoms ≥3 months post-infection, and approximately half will recover by 6 months. Male gender was associated with higher odds of Long COVID, and vaccination could potentially be protective against Long COVID in CYPs., Competing Interests: The authors have no conflict of interest to disclose.

There is little information on BNT162b2 vaccine-induced variant-specific immunogenicity, safety data and dynamics of breakthrough infections in pediatric populations. We addressed these questions using a prospective two dose BNT162b2 (10 mcg) vaccination cohort study of healthy children 5-11 years in Singapore. Follow up included blood samples at scheduled visits, daily vaccination symptom diary and confirmation of SARS-CoV-2 infection. Surrogate virus neutralization test (sVNT) and spike-specific T cell responses against SARS-CoV-2 variants were performed. The mean age of 127 participants was 8.27 years (SD 1.95) and 51.2% were males. The median sVNT level against original variant after 1 dose and 2 dose vaccination was 61.4% and 95.1% respectively (p < 0.0001). Neutralizing antibodies against the Omicron variant was the lowest, median 22.4% (IQR 16.5-30.8). However, T cell IFN-γ cytokine response against Omicron variant was high and remained so about 4 months after vaccination. Fever rate increased significantly from 4% (dose 1) to 11.5% (dose 2). The risk of Omicron breakthrough infection decreased by 7.8% for every 1% increase in sVNT inhibition level measured after dose 2 vaccination. BNT162b2 vaccines were safe, induced good T cell responses but poor neutralizing antibodies against Omicron in children. Low neutralizing antibody levels post-vaccination was predictive of subsequent breakthrough infection., (© 2023. Springer Nature Limited.)

Background: Information on variant-specific vaccine protection and the effect of previous infection variant is scarce in children. We aimed to ascertain the level of protection conferred by BNT162b2 COVID-19 vaccination against omicron variant infection (BA.4 or BA.5, and XBB) in a previously infected national paediatric cohort. We also explored the association between sequence of previous infection (variant) and vaccination on protection., Methods: We did a retrospective, population-based cohort study using the national databases of all confirmed SARS-CoV-2 infections, vaccines administered, and demographic records maintained by the Ministry of Health, Singapore. The study cohort consisted of children aged 5-11 years and adolescents aged 12-17 years who had a previous SARS-CoV-2 infection from Jan 1, 2020, to Dec 15, 2022. People who were infected during the pre-delta period or were immunocompromised (received three vaccination doses [children 5-11 years old] and four vaccinations doses [adolescents 12-17 years old]) were excluded. Those who had multiple episodes of infection before the study start date, were not vaccinated before infection but completed three doses, received bivalent mRNA vaccine, or received non-mRNA vaccine doses were also excluded. All SARS-CoV-2 infections confirmed by reverse transcriptase polymerase chain reaction or rapid antigen testing were grouped into delta, BA.1, BA.2, BA.4 or BA.5, or XBB variants using a combination of whole-genome sequencing, S-gene target failure results, and imputation. For BA.4 or BA.5, the study outcome period was June 1-Sept 30, 2022, and for XBB variants the outcome period was Oct 18-Dec 15, 2022. Incidence rate ratios between vaccinated and unvaccinated were derived using adjusted Poisson regressions and vaccine effectiveness was estimated as (1-risk ratio) × 100%., Findings: 135 197 people aged 5-17 years (79 332 children and 55 865 adolescents) were included in the cohort for the vaccine effectiveness analysis against omicron BA.4 or BA.5, and 164 704 people aged 5-17 years (97 235 children and 67 469 adolescents) were included for the analysis against omicron XBB. Approximately 47% of participants were female and 53% were male. Among those previously infected, vaccine effectiveness against BA.4 or BA.5 infection in fully vaccinated children (two doses) was 74·0% (95% CI 67·7-79·1) and in adolescents (three doses) was 85·7% (80·2-89·6). Against XBB, protection conferred with full vaccination was lower at 62·8% (95% CI 42·3-76·0) in children and 47·9% (20·2-66·1) in adolescents. In children, receipt of two-dose vaccination before first SARS-CoV-2 infection provided them with the highest protection against subsequent BA.4 or BA.5 infection at 85·3% (95% CI 80·2-89·1); however, this was not shown to be the case for adolescents. First infection variant had an effect on vaccine effectiveness against omicron BA.4 or BA.5 reinfection in the following descending order: BA.2 conferred the highest protection (92·3% [95% CI 88·9-94·7] in children and 96·4% [93·5-98·0] in adolescents) followed by BA.1 (81·9% [75·9-86·4] in children and 95·0% [91·6-97·0] in adolescents), and delta which conferred the lowest protection (51·9% [5·3-75·6] in children and 77·5% [63·9-86·0] in adolescents)., Interpretation: In previously infected children and adolescents, BNT162b2 vaccination provided additional protection against omicron BA.4 or BA.5 and XBB variants compared with those who remained unvaccinated. Hybrid immunity against XBB was lower than against BA.4 or BA.5, especially in adolescents. Early vaccination of previously uninfected children before their first SARS-CoV-2 exposure could potentially strengthen population immunity resilience against future variants., Funding: None., Competing Interests: Declaration of interests CFY declares funding to attend conferences and honorarium from Sanofi, Pfizer, and Takeda, outside of the submitted work. All other authors declare no competing interests., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Background: Clinical utility of universal antigen rapid test (ART) in the pediatric setting is unknown. We aimed to assess the performance and utility of universal ART in hospitalized children (≥5-year-old) to prevent nosocomial COVID-19 transmission., Methods: Cross-sectional study involving all hospitalized pediatric patients aged ≥5-year-old from 2 periods during Omicron wave. Clinical data, ART and polymerase chain reaction test results were collected., Results: A total of 444 patients were included from the 2 study periods, and 416 patients (93.7%) had concordant results between ART and polymerase chain reaction. The overall sensitivity and specificity of ART were 83.3% (95% CI: 75.2-89.3) and 97.5% (95% CI: 95.0-98.8), respectively. Negative predictive values of ART between the Omicron emergence and Omicron peak periods for a probable case group were 71.4% and 66.7%, respectively, and for a suspect case group 91.4% and 75.0%, respectively. Negative predictive values for an unlikely case group was >95% in both periods. Positive predictive value of ART was >85% for probable and suspect case groups in both periods. Seventy-five percent of patients (n = 15) who were incorrectly classified as SARS-CoV-2 negative by ART had potentially viable virus. No large nosocomial transmission clusters were detected., Conclusions: Universal ART screening may limit nosocomial outbreaks in hospitalized children. The performance can be optimized by considering clinical symptoms, exposure and periods within COVID waves., (Copyright © 2022 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.)

Poliomyelitis, or polio, is a highly infectious disease and can result in permanent flaccid paralysis of the limbs. Singapore was certified polio-free by the World Health Organization (WHO) on 29 October 2000, together with 36 other countries in the Western Pacific Region. The last imported case of polio in Singapore was in 2006. Fortunately, polio is vaccine-preventable-the world saw the global eradication of wild poliovirus types 2 and 3 achieved in 2015 and 2019, respectively. However, in late 2022, a resurgence of paralytic polio cases from vaccine-derived poliovirus (VDPV) was detected in countries like Israel and the US (specifically, New York); VDPV was also detected during routine sewage water surveillance with no paralysis cases in London, UK. Without global eradication, there is a risk of re-infection from importation and spread of wild poliovirus or VDPV, or new emergence and circulation of VDPV. During the COVID-19 pandemic, worldwide routine childhood vaccination coverage fell by 5% to 81% in 2020-2021. Fortunately, Singapore has maintained a constantly high vaccination coverage of 96% among 1-year-old children as recorded in 2021. All countries must ensure high poliovirus vaccination coverage in their population to eradicate poliovirus globally, and appropriate interventions must be taken to rectify this if the coverage falters. In 2020, WHO approved the emergency use listing of a novel oral polio vaccine type 2 for countries experiencing circulating VDPV type 2 outbreaks. Environmental and wastewater surveillance should be implemented to allow early detection of "silent" poliovirus transmission in the population, instead of relying on clinical surveillance of acute flaccid paralysis based on case definition alone.

Introduction: Multisystem inflammatory syndrome in children (MIS-C) is a rare inflammatory syndrome with multisystem involvement affecting children exposed to COVID-19. This condition is rarely reported in East Asia and was not detected in Singapore until 2021. We present 12 cases of MIS-C diagnosed in KK Women's and Children's Hospital (KKH) from October 2021 to December 2021., Method: We conducted an observational study on cases fulfilling the Singapore Ministry of Health criteria for MIS-C from January 2020 to December 2021 in KKH. Medical records were reviewed to obtain information on clinical presentation, disease course, treatment received and outcomes., Results: In the 12 cases detected, the median age was 7.50 years (interquartile range 4.00-9.25); 8 were male. All patients had mucocutaneous symptoms similar to Kawasaki disease. Other commonly involved systems were: haematological (coagulopathy 100%, lymphopaenia 91.70% and thrombocytopaenia 75.00%), gastrointestinal (75.00%) and cardiovascular (83.30%). Six patients (50.00%) had shock and were admitted to the intensive care unit. The majority of patients received treatment within 2 days of hospitalisation with intravenous immunoglobulin (IVIg) and steroids. All survived; the majority had normal echocardiograms and no long-term organ sequelae at 6 months post-discharge., Conclusion: MIS-C emerged in Singapore as the incidence of COVID-19 in the community increased in 2021. The clinical presentation of our patients is similar to earlier reports, with some significant differences from Kawasaki disease. Multidisciplinary management, timely diagnosis, and early initiation of treatment with IVIg and steroids likely contributed to comparatively good outcomes. Our cases highlight the need for continued awareness of MIS-C among physicians, and surveillance of its incidence, short- and long-term outcomes.

Introduction: Children infected with COVID-19 are susceptible to severe manifestations. We aimed to develop and validate a predictive model for severe/ critical pediatric COVID-19 infection utilizing routinely available hospital level data to ascertain the likelihood of developing severe manifestations., Methods: The predictive model was based on an analysis of registry data from COVID-19 positive patients admitted to five tertiary pediatric hospitals across Asia [Singapore, Malaysia, Indonesia (two centers) and Pakistan]. Independent predictors of severe/critical COVID-19 infection were determined using multivariable logistic regression. A training cohort (n = 802, 70%) was used to develop the prediction model which was then validated in a test cohort (n = 345, 30%). The discriminative ability and performance of this model was assessed by calculating the Area Under the Curve (AUC) and 95% confidence interval (CI) from final Receiver Operating Characteristics Curve (ROC)., Results: A total of 1147 patients were included in this analysis. In the multivariable model, infant age group, presence of comorbidities, fever, vomiting, seizures and higher absolute neutrophil count were associated with an increased risk of developing severe/critical COVID-19 infection. The presence of coryza at presentation, higher hemoglobin and platelet count were associated with a decreased risk of severe/critical COVID-19 infection. The AUC (95%CI) generated for this model from the training and validation cohort were 0.96 (0.94, 0.98) and 0.92 (0.86, 0.97), respectively., Conclusion: This predictive model using clinical history and commonly used laboratory values was valuable in estimating the risk of developing a severe/critical COVID-19 infection in hospitalized children. Further validation is needed to provide more insights into its utility in clinical practice., Competing Interests: The authors have declared that no competing interests exist.

We present a country specific method to calculate the COVID-19 vaccination coverage needed for herd immunity by considering age structure, age group-specific contact patterns, relative infectivity and susceptibility of children to adults, vaccination effectiveness and seroprevalence prior to vaccination. We find that across all six countries, vaccination of adults age 60 and above has little impact on R eff and this is could be due to the smaller number of contacts between this age group and the rest of the population according to the contact matrices used. If R 0 is above 6, herd immunity by vaccine alone is unattainable for most countries either if vaccination is only available for adults or that vaccine effectiveness is lower at 65% against symptomatic infections. In this situation, additional control measures, booster shots, if they improve protection against infection, or the extension of vaccination to children, are required. For a highly transmissible variant with R 0 up to 8, herd immunity is possible for all countries and for all four scenarios of varying relative infectivity and susceptibility of children compared to adults, if vaccine effectiveness is very high at 95% against symptomatic infections and that high vaccination coverage is achieved for both adults and children. In addition, we show that the effective reproduction number will vary between countries even if the same proportion of the population is vaccinated, depending on the demographics, the contact rates and the previous pre-vaccination seroprevalence in the country. This therefore means that care must be taken in extrapolating population level impacts of certain vaccine coverages from one country to another., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

There is a scarcity of data regarding coronavirus disease 2019 (COVID-19) infection in children from southeast and south Asia. This study aims to identify risk factors for severe COVID-19 disease among children in the region. This is an observational study of children with COVID-19 infection in hospitals contributing data to the Pediatric Acute and Critical Care COVID-19 Registry of Asia. Laboratory-confirmed COVID-19 cases were included in this registry. The primary outcome was severity of COVID-19 infection as defined by the World Health Organization (WHO) (mild, moderate, severe, or critical). Epidemiology, clinical and laboratory features, and outcomes of children with COVID-19 are described. Univariate and multivariable logistic regression models were used to identify risk factors for severe/critical disease. A total of 260 COVID-19 cases from eight hospitals across seven countries (China, Japan, Singapore, Malaysia, Indonesia, India, and Pakistan) were included. The common clinical manifestations were similar across countries: fever (64%), cough (39%), and coryza (23%). Approximately 40% of children were asymptomatic, and overall mortality was 2.3%, with all deaths reported from India and Pakistan. Using the multivariable model, the infant age group, presence of comorbidities, and cough on presentation were associated with severe/critical COVID-19. This epidemiological study of pediatric COVID-19 infection demonstrated similar clinical presentations of COVID-19 in children across Asia. Risk factors for severe disease in children were age younger than 12 months, presence of comorbidities, and cough at presentation. Further studies are needed to determine whether differences in mortality are the result of genetic factors, cultural practices, or environmental exposures.

An accurate depiction of the convalescent COVID-19 immunome will help delineate the immunological milieu crucial for disease resolution and protection. Using mass cytometry, we characterized the immune architecture in patients recovering from mild COVID-19. We identified a virus-specific immune rheostat composed of an effector T (T eff ) cell recall response that is balanced by the enrichment of a highly specialized regulatory T (T reg ) cell subset. Both components were reactive against a peptide pool covering the receptor binding domain (RBD) of the SARS-CoV-2 spike glycoprotein. We also observed expansion of IFNγ + memory CD4 + T cells and virus-specific follicular helper T (T FH ) cells. Overall, these findings pinpoint critical immune effector and regulatory mechanisms essential for a potent, yet harmless resolution of COVID-19 infection., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Yeo, Leong, Tay, Nadua, Anderson, Lim, Ng, Poh, Guo, Yaung, Kumar, Wasser, Hazirah, Sutamam, Chua, Qui, Foo, Gamage, Yeo, Ramakrishna, Arkachaisri, Young, Lye, Wang, Chong, Tan, Li, Kam, Ginhoux, Thoon, Chan, Yung and Albani.)

Transmission risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in schools is unknown. Our investigations, especially in preschools, could not detect SARS-CoV-2 transmission despite screening of symptomatic and asymptomatic children. The data suggest that children are not the primary drivers of SARS-CoV-2 transmission in schools and could help inform exit strategies for lifting of lockdowns., (© The Author(s) 2020. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Background: Coronavirus disease 2019 (COVID-19) has impacted the provision of health services in all specialties. We aim to study the impact of COVID-19 on the utilization of pediatric hospital services including emergency department (ED) attendances, hospitalizations, diagnostic categories and resource utilization in Singapore., Methods: We performed a retrospective review of ED attendances and hospital admissions among children < 18 years old from January 1st to August 8th 2020 in a major pediatric hospital in Singapore. Data were analyzed in the following time periods: Pre-lockdown (divided by the change in Disease Outbreak Response System Condition (DORSCON) level), during-lockdown and post-lockdown. We presented the data using proportions and percentage change in mean counts per day with the corresponding 95% confidence intervals (CIs)., Results: We attended to 58,367 children with a mean age of 5.1 years (standard deviation, SD 4.6). The mean ED attendance decreased by 331 children/day during lockdown compared to baseline (p < 0.001), attributed largely to a drop in respiratory (% change - 87.9, 95% CI - 89.3 to - 86.3, p < 0.001) and gastrointestinal infections (% change - 72.4, 95%CI - 75.9 to - 68.4, p < 0.001). Trauma-related diagnoses decreased at a slower rate across the same periods (% change - 40.0, 95%CI - 44.3 to - 35.3, p < 0.001). We saw 226 children with child abuse, with a greater proportion of total attendance seen post-lockdown (79, 0.6%) compared to baseline (36, 0.2%) (p < 0.001). In terms of ED resource utilization, there was a decrease in the overall mean number of procedures performed per day during the lockdown compared to baseline, driven largely by a reduction in blood investigations (% change - 73.9, 95%CI - 75.9 to - 71.7, p < 0.001)., Conclusions: We highlighted a significant decrease in infection-related presentations likely attributed to the lockdown and showed that the relative proportion of trauma-related attendances increased. By describing the impact of COVID-19 on health services, we report important trends that may provide guidance when planning resources for future pandemics.

The epidemiological target of lockdowns is to drive down the effective reproduction number (Rt) to less than 1. A key unknown is the duration that lockdowns need to be in place to achieve this and which lockdown measures are effective. Daily number of laboratory confirmed community coronavirus 2019 cases were extracted from regular reports from the Ministry of Health Singapore from 20 March 2020 to 4 May 2020. We generated daily Rt to estimate the time needed for these public health lockdown measures to control the spread of severe acute respiratory syndrome coronavirus 2 as demonstrated by Rt < 1. It took about 14 days of nationwide lockdown for the Rt trend to change and start falling. The upper limit of the 95% confidence interval for time to Rt < 1 was day 15 of lockdown. We have shown that it is possible to start 'bending the Rt curve' about 2 weeks after implementation of specific lockdown measures with strict compliance.