SARS-CoV-2 Among Infants <90 Days of Age Admitted for Serious Bacterial Infection Evaluation

Risk of Urinary Tract Infection and Bacteremia in Infants Infected With COVID-19

OBJECTIVE

Our objective was to evaluate the risk of urinary tract infection (UTI) and bacteremia in infants 1 year or less of age infected with COVID-19.

METHODS

This was a retrospective study from TriNetX database in the United States. This study was from March 11, 2020, to May 11, 2023, during the COVID-19 pandemic. Patients were included if they were infants, 1 year or less, had a fever, and had a COVID-19 polymerase chain reaction test 1 week before or after presentation to the emergency department (ED) or hospital. We compared outcomes of bacteremia and a UTI in those with COVID-19 and those without COVID-19. Propensity matching was done to account for the confounders of age, gender, race, immune disorders, genitourinary abnormalities, preterm birth, and circumcision.

RESULTS

Infants who were positive for COVID-19 were at a reduced risk of UTI and bacteremia. There was a significant decreased risk of having a UTI if one had COVID-19 (1.0%) versus those without COVID-19 (2.3%) (risk ratio = 0.37, 95% confidence interval = 0.37-0.50, P < 0.001). For bacteremia, there was also a decreased risk if the infant had COVID-19 (0.4%), versus those without COVID-19 (0.5%) (risk ratio = 0.74, 95% confidence interval = 0.56-0.97, P = 0.03).

CONCLUSIONS

Infants with fever found to have COVID-19 had lower risks of UTI and bacteremia.

Impact of viral testing on duration of antibiotic treatment and hospitalisation of febrile infants

AIM

To assess the duration of antimicrobial treatment; hospital length of stay; and invasive bacterial infections rates in hospitalised infants following the adoption of a management guideline.

METHODS

Faculty agreed to a standard of 24 h of antibiotic treatment for well-appearing febrile infants with proven viral infection and no growth on bacterial cultures. The outcomes were the duration of hospitalisation and antibiotic treatment of febrile infants less than 8 weeks of age who have enterovirus, parechovirus, respiratory viruses detected. We monitored re-admissions and missed invasive infections.

RESULTS

Of the total 1696 infants studied, the median antibiotic treatment duration decreased from 31.5 to 24.8 h in virus-infected infants ≤21 days of age (p = 0.02) and from 26 to 19.7 h in infants 22-56 days of age (p < 0.001). The decrease was less in infants not infected with a virus. No patient had an invasive infection identified after discharge.

CONCLUSION

The implementation of our care standard resulted in reduction in antibiotic treatment duration without known delayed diagnosis of bacterial infections. Infants without a proven viral aetiology may need further study to inform management decisions.

Severe and invasive bacterial infections in infants aged less than 90 days with and without SARS-CoV-2 infection

BACKGROUND

Fever in children represents one of the most common causes of medical evaluation. Infants younger than 90 days of age are at higher risk of severe and invasive bacterial infections (SBI and IBI). However, clinical signs and symptoms of viral and bacterial infections in young infants are frequently similar, and several studies have shown that the risk of SBIs remains non-negligible even in the presence of a positive point-of-care viral test. Our study aims to evaluate whether the proportion of SBIs and IBIs in febrile infants younger than 90 days during the COVID-19 pandemic was higher than that in the pre-pandemic period, and to describe the proportion of SBIs and IBIs in infants with and without SARS-CoV-2 infection.

METHODS

This was a retrospective single-center cohort study conducted at the Children's Hospital of the University of Padua in Italy, involving febrile young infants evaluated in the Pediatric Emergency Department (PED) and admitted to Pediatric Acute Care Unit (PACU) between March 2017 to December 2022. Infants admitted before the COVID-19 pandemic were compared to infants admitted during the pandemic period and SARS-CoV-2 positive patients to the negative ones.

RESULTS

442 febrile infants younger than 90 days were evaluated in Padua PED and admitted to the wards. The proportion of SBIs and IBIS did not significantly change over the study periods, ranging between 10.8% and 32.6% (p = 0.117) and between 0% and 7.6%, respectively (p = 0.367). The proportion of infants with a diagnosis of SBIs and IBIs was higher in the SARS-CoV-2 negative group (30.3% and 8.2%, respectively) compared to the positive group (8.5% and 2.8%, respectively) (p < 0.0001). The most common diagnosis in both groups was UTI, mainly caused by E. coli. A similar proportion of blood and urine cultures were performed, whereas lumbar puncture was more frequently performed in SARS-CoV-2 negative infants (40.2% vs 16.9%, p = 0.001).

CONCLUSIONS

Although the risk of concomitant serious bacterial infection with SARS-CoV-2 is low, it remains non-negligible. Therefore, even in SARS-CoV-2-positive febrile infants, we suggest that the approach to screening for SBIs remains cautious.

Prevalence of invasive bacterial infection in febrile infants ≤90 days with a COVID-19 positive test: a systematic review and meta-analysis

BACKGROUND

Febrile infants with an infection by influenza or enterovirus are at low risk of invasive bacterial infection (IBI).

OBJECTIVE

To determine the prevalence of IBI among febrile infants ≤90 days old with a positive COVID-19 test.

METHODS

MEDLINE, Embase, Cochrane Central Register databases, Web of Science, ClinicalTrials.gov and grey literature were searched for articles published from February 2020 to May 2023.

INCLUSION CRITERIA

researches reporting on infants ≤90 days of age with fever and a positive test for SARS-CoV-2 (antigen test/PCR). Case reports with <3 patients, articles written in a language other than English, French or Spanish, editorials and other narrative studies were excluded. Preferred Reposting Items for Systematic Reviews and Meta-analysis guidelines were followed, and the National Institutes of Health Quality Assessment Tool was used to assess study quality. The main outcome was the prevalence of IBI (a pathogen bacterium identified in blood and/or cerebrospinal fluid (CSF)). Forest plots of prevalence estimates were constructed for each study. Heterogeneity was assessed and data were pooled by meta-analysis using a random effects model. A fixed continuity correction of 0.01 was added when a study had zero events.

RESULTS

From the 1023 studies and 3 databases provided by the literature search, 33 were included in the meta-analysis, reporting 3943 febrile infants with a COVID-19 positive test and blood or CSF culture obtained. The pooled prevalence of IBI was 0.14% (95% CI, 0.02% to 0.27%). By age, the prevalence of IBI was 0.56% (95% CI, 0.0% to 1.27%) in those 0-21 days old, 0.53% (95% CI, 0.0% to 1.22%) in those 22-28 days old and 0.11% (95% CI, 0.0% to 0.24%) in those 29-60 days old.

CONCLUSION

COVID-19-positive febrile infants ≤90 days old are at low risk of IBI, especially infants >28 days old, suggesting this subgroup of patients can be managed without blood tests.

PROSPERO REGISTRATION NUMBER

CRD42022356507.

COVID-19 in hospitalized infants aged under 3 months: multi-center experiences across Turkey

To investigate coronavirus disease 2019 (COVID-19) in infants aged 0 to 3 months because there is currently a significant gap in the literature on the subject. A cross-sectional study was conducted with the involvement of 19 medical centers across Turkey and 570 infants. The majority of the patients were male (58.2%), and the three most common symptoms were fever (78.2%), cough (44.6%), and feeding intolerance (39.9%). The results showed that a small percentage of infants had positive blood (0.9%) or urine cultures (10.2%). Most infants presented with fever (78.2%). Children without underlying conditions (UCs) had mostly a complicated respiratory course and a normal chest radiography. Significant more positive urine culture rates were observed in infants with fever. A higher incidence of respiratory support requirements and abnormal chest findings were seen in infants with chronic conditions. These infants also had a longer hospital stay than those without chronic conditions.  Conclusions: Our study discloses the clinical observations and accompanying bacterial infections found in infants aged under 3 months with COVID-19. These findings can shed light on COVID-19 in infancy for physicians because there is limited clinical evidence available. What is Known: • COVID-19 in infants and older children has been seen more mildly than in adults. • The most common symptoms of COVID-19 in infants are fever and cough, as in older children and adults. COVID-19 should be one of the differential diagnoses in infants with fever. What is New: • Although most infants under three months had fever, the clinical course was uneventful and respiratory complications were rarely observed in healthy children. • Infants with underlying conditions had more frequent respiratory support and abnormal chest radiography and stayed longer in the hospital.

Bacterial coinfection in young febrile infants with SARS-CoV-2 infection

We aimed to assess the prevalence of serious bacterial infections (SBIs) in febrile infants < 90 days of age with SARS-CoV-2 infection versus SARS-CoV-2-negative febrile infants. A retrospective cohort study was conducted in a tertiary pediatric emergency department between March 2020 and October 2022. Febrile infants < 90 days of age who underwent SARS-CoV-2 testing were included. SBIs were defined as urinary tract infection (UTI), bacteremia, and/or bacterial meningitis; bacteremia and bacterial meningitis were considered invasive bacterial infections (IBIs). SBIs rates were compared between SARS-CoV-2-positive and negative infants and stratified by age. We included 779 infants: 221 (28.4%) SARS-CoV-2-positive and 558 (71.6%) SARS-CoV-2-negative. The SBI rate in the SARS-CoV-2-positive group was 5.9% vs 22.9% in the SARS-CoV-2-negative group (p < 0.001; relative risk (RR) 0.26; [95% CI 0.15-0.44]); the most common infections were UTI (5.4% vs 22.0%; p < 0.001). The IBI rate was 0.5% in the SARS-CoV-2-positive group vs. 3.2% in the negative group (p = 0.024; RR 0.14 [95% CI 0.02-1.04]). There were no cases of bacterial meningitis in the positive infants. SARS-CoV-2-positive infants > 28 days of age had a decreased likelihood of SBI (RR 0.22 [95% CI 0.11-0.43]), with no cases of IBI identified.     Conclusions: Febrile infants < 90 days of age with SARS-CoV-2 infection are at significantly lower risk of SBIs than those who are SARS-CoV-2-negative. Nevertheless, the rate of UTI remains considerable in SARS-CoV-2-positive infants. SARS-CoV-2 detection may be relevant in considering IBI risk for well-appearing febrile infants 29-89 days of age. What is Known: • Febrile infants with laboratory-confirmed viral infections have a significantly lower risk of serious bacterial infections when compared to those without them. Data focusing on very young febrile infants with a SARS-CoV-2 infection is still limited. What is New: • Young febrile infants with SARS-CoV-2 infection are at significantly lower risk of serious bacterial infections than those who are SARS-CoV-2-negative. Nevertheless, the rate of urinary tract infection remains considerable. SARS-CoV-2 detection may be relevant in considering invasive bacterial infection risk for well-appearing febrile infants 29-89 days of age.

Severe Acute Respiratory Syndrome Coronavirus 2 in Infants Younger Than 90 Days Presenting to the Pediatric Emergency Department: Clinical Characteristics and Risk of Serious Bacterial Infection

OBJECTIVES

There are scant data on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in infants younger than 90 days. This study was designed to characterize COVID-19 presentation and clinical course in this age group and evaluate the risk of serious bacterial infection.

METHODS

Data on all SARS-CoV-2-polymerase chain reaction-positive infants presenting to the pediatric emergency department (PED) were retrospectively collected, followed by a case-control study comparing those infants presenting with fever (COVID group) to febrile infants presenting to the PED and found to be SARS-CoV-2 negative (control group).

RESULTS

Of the 96 PCR-positive SARS-CoV-2 infants who met the inclusion criteria, the most common presenting symptom was fever (74/96, 77.1%) followed by upper respiratory tract infection symptoms (42/96, 43.8%). Four (4.2%) presented with symptoms consistent with brief resolved unexplained event (4.2%).Among the febrile infants, the presenting symptoms and vital signs were similar in the COVID and control groups, with the exception of irritability, which was more common in the control group (8% and 26%; P < 0.01). The SARS-CoV-2-positive infants had decreased inflammatory markers including: C-reactive protein (0.6 ± 1 mg/dL vs 2.1 ± 2.7 mg/dL; P < 0.0001), white blood cell count (9.3 ± 3.4 × 10 9 /L vs 11.8 ± 5.1 × 10 9 /L; P < 0.001), and absolute neutrophils count (3.4 ± 2.4 × 10 9 /L vs 5.1 ± 3.7 × 10 9 /L; P < 0.001). The rate of invasive bacterial infection was similar between groups (1.4% and 0%; P = 0.31). No mortality was recorded. Although not significantly different, urinary tract infections were less common in the COVID group (7% and 16%; P = 0.07).

CONCLUSIONS

The SARS-CoV-2 infection in infants aged 0 to 90 days who present to the PED seems to be mostly mild and self-limiting, with no increased risk of serious bacterial infection.

Bacterial Infections and Clinical Outcomes Among Febrile Infants up to 90 Days Old With SARS-CoV-2 Infection: A Multicenter Cohort Study

We present a large, multicenter, cohort study that aimed to assess bacterial infection rates among febrile infants up to 90 days old presenting to the pediatric emergency department with severe acute respiratory syndrome coronavirus 2 infection during 2021-2022 throughout successive variant waves. Overall, 417 febrile infants were included. Twenty-six infants (6.2%) had bacterial infections. All bacterial infections consisted of urinary tract infections, and there were no invasive bacterial infections. There was no mortality.

Prevalence of Urinary Tract Infection, Bacteremia, and Meningitis Among Febrile Infants Aged 8 to 60 Days With SARS-CoV-2

Importance

The prevalence of urinary tract infection (UTI), bacteremia, and bacterial meningitis in febrile infants with SARS-CoV-2 is largely unknown. Knowledge of the prevalence of these bacterial infections among febrile infants with SARS-CoV-2 can inform clinical decision-making.

Objective

To describe the prevalence of UTI, bacteremia, and bacterial meningitis among febrile infants aged 8 to 60 days with SARS-CoV-2 vs without SARS-CoV-2.

Design, Setting, and Participants

This multicenter cross-sectional study was conducted as part of a quality improvement initiative at 106 hospitals in the US and Canada. Participants included full-term, previously healthy, well-appearing infants aged 8 to 60 days without bronchiolitis and with a temperature of at least 38 °C who underwent SARS-CoV-2 testing in the emergency department or hospital between November 1, 2020, and October 31, 2022. Statistical analysis was performed from September 2022 to March 2023.

Exposures

SARS-CoV-2 positivity and, for SARS-CoV-2-positive infants, the presence of normal vs abnormal inflammatory marker (IM) levels.

Main Outcomes and Measures

Outcomes were ascertained by medical record review and included the prevalence of UTI, bacteremia without meningitis, and bacterial meningitis. The proportion of infants who were SARS-CoV-2 positive vs negative was calculated for each infection type, and stratified by age group and normal vs abnormal IMs.

Results

Among 14 402 febrile infants with SARS-CoV-2 testing, 8413 (58.4%) were aged 29 to 60 days; 8143 (56.5%) were male; and 3753 (26.1%) tested positive. Compared with infants who tested negative, a lower proportion of infants who tested positive for SARS-CoV-2 had UTI (0.8% [95% CI, 0.5%-1.1%]) vs 7.6% [95% CI, 7.1%-8.1%]), bacteremia without meningitis (0.2% [95% CI, 0.1%-0.3%] vs 2.1% [95% CI, 1.8%-2.4%]), and bacterial meningitis (<0.1% [95% CI, 0%-0.2%] vs 0.5% [95% CI, 0.4%-0.6%]). Among infants aged 29 to 60 days who tested positive for SARS-CoV-2, 0.4% (95% CI, 0.2%-0.7%) had UTI, less than 0.1% (95% CI, 0%-0.2%) had bacteremia, and less than 0.1% (95% CI, 0%-0.1%) had meningitis. Among SARS-CoV-2-positive infants, a lower proportion of those with normal IMs had bacteremia and/or bacterial meningitis compared with those with abnormal IMs (<0.1% [0%-0.2%] vs 1.8% [0.6%-3.1%]).

Conclusions and Relevance

The prevalence of UTI, bacteremia, and bacterial meningitis was lower for febrile infants who tested positive for SARS-CoV-2, particularly infants aged 29 to 60 days and those with normal IMs. These findings may help inform management of certain febrile infants who test positive for SARS-CoV-2.

The evolving relationship between COVID-19 and serious bacterial infection evaluation in febrile neonates

AIM

The COVID-19 omicron variant surge highlighted the evolving impact of COVID-19. Febrile infants <60 days old are high risk for serious bacterial infections (SBI). This study evaluated the rate of SBI based on COVID-19 infection.

METHODS

We conducted a retrospective chart review at an urban, academic paediatric emergency department. The study enrolled infants 60 days old or less with documented fever. The primary outcome was SBI diagnosed by blood, urine, and/or cerebrospinal fluid cultures. We compared the rate of SBI between COVID-19 groups with an omicron variant and 29- to 60-day-old subgroup analyses.

RESULTS

Two hundred and thirty-three (233) infants meet the criteria. The incidence of SBI was 18.7% in the COVID-19 negative and 1.7% in the COVID-19-positive group which is statistically significant (p < 0.001). Omicron subgroup analysis did not achieve statistical significance (p = 0.62) while COVID-19-positive infants 29-60 days old had a statistically significant lower rate of SBI (p = 0.006).

CONCLUSION

The omicron variant surge provided an additional understanding of the impact of COVID-19 on these high-risk infants. These results can lead to decreased invasive testing and exposure to antibiotics as well as examine the utility of viral testing for risk stratification.

Epidemiology of Neonatal COVID-19 in the United States

OBJECTIVES

Data on coronavirus disease 2019 (COVID-19) infections in neonates are limited. We aimed to identify and describe the incidence, presentation, and clinical outcomes of neonatal COVID-19.

METHODS

Over 1 million neonatal encounters at 109 United States health systems, from March 2020 to February 2021, were extracted from the Cerner Real World Database. COVID-19 diagnosis was assessed using severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) laboratory tests and diagnosis codes. Incidence of COVID-19 per 100 000 encounters was estimated.

RESULTS

COVID-19 was diagnosed in 918 (0.1%) neonates (91.1 per 100 000 encounters [95% confidence interval 85.3-97.2]). Of these, 71 (7.7%) had severe infection (7 per 100 000 [95% confidence interval 5.5-8.9]). Median time to diagnosis was 14.5 days from birth (interquartile range 3.1-24.2). Common signs of infection were tachypnea and fever. Those with severe infection were more likely to receive respiratory support (50.7% vs 5.2%, P < .001). Severely ill neonates received analgesia (38%), antibiotics (33.8%), anticoagulants (32.4%), corticosteroids (26.8%), remdesivir (2.8%), and COVID-19 convalescent plasma (1.4%). A total of 93.6% neonates were discharged home after care, 1.1% were transferred to another hospital, and discharge disposition was unknown for 5.2%. One neonate (0.1%) with presentation suggestive of multisystem inflammatory syndrome in children died after 11 days of hospitalization.

CONCLUSIONS

Most neonates infected with SARS-CoV-2 were asymptomatic or developed mild illness without need for respiratory support. Some had severe illness requiring treatment of COVID-19 with remdesivir and COVID-19 convalescent plasma. SARS-CoV-2 infection in neonates, though rare, may result in severe disease.

Impact of COVID-19 on viral respiratory infection epidemiology in young children: A single-center analysis

Background

The COVID-19 pandemic impacts different health aspects. Concomitant with the adoption of non-pharmaceutical interventions (NPIs) to reduce the spread of SARS-CoV-2, global surveillance studies reported a reduction in occurrence of respiratory pathogens like influenza A and B virus (IAV & IBV) and respiratory syncytial virus (RSV). We hypothesized to observe this collateral benefit on viral respiratory infection epidemiology in young children.

Methods

Respiratory samples of children aged below 6 years, presenting at the outpatient clinic, emergency department, or pediatric infectious diseases department of the University Hospitals Leuven, between April 2017 and April 2021 were retrospectively analyzed. The occurrence (positivity rate), and seasonal patterns of viral respiratory infections were described. Chi-squared or Fisher's exact test (and Bonferroni correction) were used to explore differences in occurrence between 2020-2021 and previous 12-month (April to April) periods.

Results

We included 3020 samples (453 respiratory panels, 2567 single SARS-CoV-2 PCR tests). IAV and IBV were not detected from March and January 2020, respectively. For IAV, positivity rate in 2020-2021 (0%, n = 0) was significantly different from 2018-2019 (12.4%, n = 17) (p < 0.001) and 2019-2020 (15.4%, n = 19) (p < 0.001). IBV positivity rate in 2020-2021 (0%, n = 0) was not significantly different from previous periods. RSV occurrence was significantly lower in 2020-2021 (3.2%, n = 3), compared to 2017-2018 (15.0%, n = 15) (p = 0.006), 2018-2019 (16.1%, n = 22) (p = 0.002) and 2019-2020 (22.8%, n = 28) (p < 0.001). The RSV (winter) peak was absent and presented later (March-April 2021). Positivity rate of parainfluenza virus 3 (PIV-3) was significantly higher in 2020-2021 (11.8%, n = 11) than 2017-2018 (1%, n = 1) (p = 0.002). PIV-3 was absent from April 2020 to January 2021, whereas no clear seasonal pattern was distinguished the other years. For the other viruses tested, no significant differences in occurrence were observed between 2020-2021 and previous periods. From March 2020 onwards, 20 cases (0.7%) of SARS-CoV-2 were identified.

Conclusion

These findings reinforce the hypothesis of NPIs impacting the epidemiology of influenza viruses and RSV in young children. Compared to previous periods, no IAV and IBV cases were observed in the 2020-2021 study period, and the RSV peak occurred later. Since the pandemic is still ongoing, continuation of epidemiological surveillance, even on a larger scale, is indicated.

COVID-19 Infection in Well-Appearing 30- to 90-Day-Old Infants with Fever without a Source

Fever without a source (FWS) is common clinical status in the young infants. The aim of this study was to evaluate the clinical and laboratory findings of coronavirus disease (COVID-19) infection in well-appearing infants with FWS. Well-appearing febrile infants between 30 and 90 days who were evaluated as FWS in the pediatric emergency department and tested for COVID-19 were divided into two groups: COVID-19 (+) and (-). The clinical and laboratory findings of the patients were compared. The study included 95 febrile infants with FWS, and the mean age was 59.62 ± 16.82 days. The nasopharyngeal COVID-19 polymerase chain reaction test results of 29/95 (30.5%) patients were positive, while 66/95 (69.5%) were negative. The complaints of irritability and nasal congestion were found to be significantly more common in COVID-19-positive patients (p = 0.04 and p = 0.041, respectively). The hospitalization rate (p = 0.009), length of hospital stay (p = 0.026), initiation of antibiotic treatment (p < 0.001) and duration of antibiotic treatment (p = 0.036) were significantly lower in the COVID-19 (+) patients. The C-reactive protein (CRP, p < 0.001), absolute neutrophil count (ANC, p < 0.001), absolute lymphocyte count (ALC, p = 0.015), white blood cell (WBC, p < 0.001) and systemic immune-inflammation index (SII, p < 0.001) were found to be significantly lower in the COVID-19 (+) patient group. There was no significant difference between the groups in terms of neutropenia, lymphopenia or leukopenia. COVID-19 infection may present as an FWS. During the pandemic period, testing for COVID-19 among infants who were evaluated as FWS may reduce unnecessary hospitalizations and antibiotic treatments, and shorten hospital stays and duration of antibiotics.

Clinical and Laboratory Findings of SARS-CoV-2 Infection in Children Younger than 6 Months Old: Neutropenia is More Common Not Lymphopenia

BACKGROUND

Studies on age-related differences in clinical and laboratory features of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are limited. We aimed to evaluate the demographic, clinical, laboratory findings of SARS-CoV-2 infection in children younger than 6 months old and compare them with older children.

METHODS

A single-center retrospective study, including 209 confirmed SARS-CoV-2 infection cases, was conducted between 11 March 2020 and 1 September 2021. The case group consisted of 47 patients younger than 6 months old, whereas the control group consisted of 162 patients older than 6 months old.

RESULTS

The mean age of the case group was 2.77 ± 1.52 months, and the control group was 101.89 ± 65.77 months. Cough was statistically higher in the control group, and poor feeding was higher in the case group (p = 0.043, 0.010). The underlying disease rate was statistically higher in the control group; however, the hospitalization rate was higher in the case group (p = 0.036, 0.001). The case group had significantly lower median values of the absolute neutrophil count, hemoglobin and higher median values of white blood cell, absolute lymphocyte count and platelet than the control group (p < 0.05). C-reactive protein, fibrinogen values were significantly lower, and procalcitonin, D-dimer, troponin T, N-terminal pro-B-type natriuretic peptide significantly higher in the case group (p < 0.05). Lymphopenia was more common in the control group, whereas neutropenia was more common in the case group (p = 0.001, 0.011).

CONCLUSIONS

We showed that most children younger than 6 months old had mild and asymptomatic SARS-CoV-2 infection; however, the hospitalization rate was higher, and neutropenia was more common in older children. Lay summaryStudies on age-related differences in clinical and laboratory features on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in pediatric patients are limited. We aimed to evaluate the demographic, clinical and laboratory findings of SARS-CoV-2 infection in children younger than 6 months old and compare them with older children. A single-center retrospective study was conducted, including 209 SARS-CoV-2 infection cases. The case group consisted of 47 patients younger than 6 months old, and the control group consisted of 162 patients older than 6 months old. Most children younger than 6 months old had mild and asymptomatic SARS-CoV-2 infection; however, the hospitalization rate was higher than older children. Neutropenia was more common in patients younger than 6 months than older children with SARS-CoV-2 infection, even if underlying diseases were excluded.