Seroprevalence In Children Research Articles

Seroprevalence and risk factors of Toxocara canis infection in children aged 2–15 years from the southwest Iran

Human toxocariasis (HT) is one of the most prevalent zoonotic diseases with a worldwide distribution. There is no epidemiological study showing the seroprevalence of toxocariasis among children in southwest Iran, Khuzestan Province. Accordingly, this study was designed to estimate the seroprevalence of Toxocara canis (T. canis) IgG antibodies in children (2–15 years old) and assess the main risk factors associated to human infection. In this cross-sectional study, a total of 259 children were invited to participate from the southwest Iran (Abadan and Khorramshahr cities, Khuzestan Province) between April to August 2021. Serum anti-T. canis IgG antibodies were measured using a commercially available enzyme-linked immunosorbent assay (ELISA). A structured questionnaire was also employed to collect some socio-demographic information and probable risk factors associated to T. canis infection. The overall seroprevalence rate of T. canis in children was 7.3% (95% CI = 4.75 – 11.17%). The univariate analysis demonstrated that living in rural communities (P < 0.001), drinking unpurified water (P < 0.001), contact with cat (P = 0.033), consumption of improperly washed vegetables (P = 0.002), and history of drinking water from unsafe sources (P = 0.003) were risk factors associated with T. canis seroprevalence in children. However, after adjusting for confounders, multivariable logistic regression analysis verified that only drinking unpurified water (P = 0.016) remained a significant risk factor. In addition, both univariate (P = 0.032) and multivariate logistic regression analysis (P = 0.037) revealed that seropositivity of T. canis infection was significantly associated with asthma. The current report provides beneficial baseline epidemiological findings regarding the seroprevalence of T. canis in children as a vulnerable group for this infection. This data can be used by health policy makers to plan effective prevention programs and control this neglected infection among high risk subjects.

Pediatric SARS-CoV-2 Seroprevalence in Arkansas Over the First Year of the COVID-19 Pandemic.

BackgroundSevere acute respiratory syndrome coronavirus-2 (SARS-CoV-2) seroprevalence studies largely focus on adults, but little is known about spread in children. We determined SARS-CoV-2 seroprevalence in children and adolescents from Arkansas over the first year of the coronavirus disease of 2019 (COVID-19) pandemic.MethodsWe tested remnant serum samples from children ages 1-18 years who visited Arkansas hospitals or clinics for non-COVID-19-related reasons from April 2020 through April 2021 for SARS-CoV-2 antibodies. We used univariable and multivariable regression models to determine the association between seropositivity and participant characteristics.ResultsAmong 2357 participants, seroprevalence rose from 7.9% in April/May 2020 (95% CI, 4.9-10.9) to 25.0% in April 2021 (95% CI, 21.5-28.5). Hispanic and black children had a higher association with antibody positivity than non-Hispanic and white children, respectively, in multiple sampling periods.ConclusionsBy spring 2021, most children in Arkansas were not infected with SARS-CoV-2. With the emergence of SARS-CoV-2 variants, recognition of long-term effects of COVID-19, and the lack of an authorized pediatric SARS-CoV-2 vaccine at the time, these results highlight the importance of including children in SARS-CoV-2 public health, clinical care, and research strategies.

Seroprevalence of hepatitis C virus infection in children: A systematic review and meta-analysis.

Estimates of paediatric hepatitis C virus (HCV) seroprevalence are needed to aid treatment scaling-up, screening and detection approach in this age range, with the ultimate goal of global HCV eradication. The aim of this study was to gather all of the available information on HCV seroprevalence in children all around the world. We searched PubMed, Scopus, Web of Science (WOS), Wiley and EBSCO databases for all studies evaluating HCV seroprevalence in children; however, studies examining seroprevalence in high-risk children or specific groups were excluded. Only 20 articles with 48 963 people met our inclusion criteria, with an overall prevalence of 0.904% and a 95% confidence interval (CI) of 0.543 to 1.355. Seroprevalence was higher in research published prior to 2010 than in those published after 2010 (0.77% vs. 0.53%). Few studies were conducted to assess the seroprevalence of HCV in children worldwide. However, the worldwide pooled seroprevalence of HCV in children in these studies is low (less than 1%).

Continuous monitoring of SARS-CoV-2 seroprevalence in children using residual blood samples from routine clinical chemistry.

The assessment of SARS-CoV-2 infections in children is still challenging, but essential for appropriate political decisions. The aim of this study was to investigate whether residual blood samples can be used for SARS-CoV-2 seroprevalence monitoring in pediatrics. In this repeated cross-sectional cohort study, anonymous residual blood samples from pediatric patients aged 0-17 years were collected in three time-periods (Oct.-Nov. 2020, April 2021, and June-July 2021) and analyzed for SARS-CoV-2 Spike protein (anti-S) and nucleocapsid (anti-N) antibodies using commercial antibody assays. 28 reactive samples were used to compare antibody levels with a pseudotyped neutralization assay. The results were further compared to the official national COVID-19 surveillance data to calculate the number of unreported cases. In total, n=2,626 individual blood samples were analyzed. In this unvaccinated pediatric cohort anti-S and anti-N antibody seroprevalence increased over the three time periods (anti-S: 1.38-9.16%, and 14.59%; anti-N: 1.26%, to 6.19%, and 8.56%). Compared to the national surveillance data this leads to a 3.93-5.66-fold increase in the number of unreported cases. However, a correlation between the cumulative incidence of the individual provinces and our assigned data was found (r=0.74, p=0.0151). In addition, reactive samples with anti-S and anti-N and samples with only anti-S showed neutralization capabilities (11/14 and 8/14, respectively). Anti-S levels were not significantly different between age groups and sexes (all p>0.05). The present study suggests that residual blood samples from routine laboratory chemistry could be included in the estimation of the total SARS-CoV-2 seroprevalence in children.

Evolution of SARS-CoV-2 IgG Seroprevalence in Children and Factors Associated with Seroconversion: Results from a Multiple Time-Points Study in Friuli-Venezia Giulia Region, Italy.

Data on the effective burden of the SARS-CoV-2 pandemic in the pediatric population are limited. We aimed at assessing the prevalence of SARS-CoV-2 IgG antibodies in children at three subsequent time-points. The study was conducted between January 2021 and July 2021 among children referring to the Research Institute for Maternal and Child Health “Burlo Garofolo” in Trieste, a referral regional hospital in Friuli Venezia Giulia, Italy. A multivariate analysis was conducted to assess factors independently associated with seroconversion. A total of 594 children were included. Anti-SARS-CoV-2 trimeric Spike protein IgG antibodies were found in 32 (15.4%) children tested in April-May and in 20 (11.8%) in June–July 2021, compared with 24 (11.1%) of those tested in January–February 2021 (p = 0.37, Armitage exact test for trend over time p = 0.76). A subgroup analysis and a multivariate logistic regression analysis were performed considering sociodemographic, clinical, and historical variables. Three categories of children showed statistically significant increased odds of positive anti-SARS-CoV-2 IgG antibodies: children previously positive to a nasopharyngeal swab (AdjOR 15.41, 95%CI 3.44–69.04, p < 0.001), cohabitant with a person with an history of a previous positive nasopharyngeal swab (AdjOR 9.95, 95%CI 5.35–18.52, p < 0.001), and children with a foreign citizenship (AdjOR 2.4, 95%CI 1.05–5.70, p = 0.002). The study suggests that seroprevalence studies may be of limited help in estimating the prevalence of the COVID-19 pandemic in children. Further studies are needed to identify other markers of previous SARS-CoV-2 infection in children, such as CD4+ T cells or memory B-cells.

SARS-CoV-2 seroprevalence in Portugal following the third epidemic wave: results of the second National Serological Survey (ISN2COVID-19)

Background Integrated approaches to surveillance of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection are important for public health actions. The 2nd National Serological Survey (ISN2COVID-19) aimed to characterize the extent of SARS-CoV-2 infection and vaccine-induced response in the Portuguese population following the third epidemic wave and the launch of the vaccination campaign. Methods A cross-sectional study was performed using data on 8463 Portuguese 1–79 years of age, collected in February and March, 2021. SARS-CoV-2 IgM and IgG (anti-nucleoprotein and anti-spike) antibodies were determined in serum samples using Abbott Architect chemiluminescent microparticle assays. Post-infection and vaccine-induced seroprevalence with 95% confidence intervals (95%CI) were estimated in the overall sample and stratified by population characteristics. Results The estimated seroprevalence was 15.5% (95%CI:14.6–16.5%), of which 13.5% (95%CI: 12.6–14.4%) was attributable to natural infection and 2.0% (95%CI:1.7–2.4%) to vaccination. The lowest seroprevelence was observed in persons aged 70–79 years (8.9% 95%CI:6.8–11.6), while seroprevalence in children (14.3%; 95%CI:11.5–17.6%) and adolescents (12.9%; 95%CI:10.5–15.7%) was similar to that of persons aged between 20 and 69 years. Of seropositive individuals, 22.6% (95%CI:19.7–25.9%) did not report any symptoms in 6 months prior to interview. Of persons with completed vaccination (2-doses), 98.6% (95%CI: 93.0–99.7%) had specific IgG (anti-S) antibodies. Conclusions After the third epidemic wave, the post-infection SARS-CoV-2 seroprevalence was 1.7 times higher than the cumulative incidence based on PCR-testing, but was higher (2.7 times) in children may be due to the high proportion of asymptomatic and mild infections.

Impact of varicella vaccination in Argentina: Seroprevalence in children and adults in a pediatric hospital

BackgroundVaricella is the primary infection caused by varicella-zoster virus (VZV). In Argentina, the varicella vaccine was introduced in the National Immunization Programme in 2015 as a single dose scheduled at 15 months of age. ObjectivesTo estimate VZV seroprevalence in a healthy hospital based population before and after vaccine introduction to the NIP. Material y MethodsCross-sectional, observational, analytic study. Healthy subjects 1–40 years of age were included between June and December 2019 and tested for VZV-antibodies. Results were compared to data from a similar prevaccination study. ResultsOut of 599 samples, 11 indeterminate results were excluded, 424 were positive; overall seroprevalence rate was 72.1% (95 %CI = 68,3–75,8%). No differences were observed between pre and post vaccination studies for overall prevalence or between age groups, except for vaccinated children aged 11–15 (p = 0,005). Rates increased in both periods in subjects aged 6 years or older. Primary vaccine failures were 21%; in subjects <5 years 83% seropositive cases had been vaccinated, in >5 year-olds >90% seropositive cases were associated with a history of infection (OR: 10,4; IC95%: 6,4–16,8; p < 0,001) or household contact (OR:4,8; IC95%: 3,1–7,6; p < 0,001). Vaccination protected against disease (OR: 0.25; 95 %CI: 0.09–0.68; p = 0.004). Conclusionseroprevalence was high in all age groups except in unvaccinated 12 to 15-month infants. Seropositivity was due to vaccination in 15 months to 5 year-old children and to infection in older children.

SARS-CoV-2 seroprevalence in children and their family members, July-October 2020, Brussels.

The aim of this study was to estimate the seroprevalence of SARS-CoV-2 antibodies in a pediatric population after the first pandemic wave in Belgium. All patients requiring a blood sample between 1 July 2020 and 31 October 2020 in our institution were invited to participate. Their parents and siblings could also participate to estimate familial transmission and the congruence between serological statuses. A questionnaire was completed for each participant to identify symptoms consistent with COVID-19 in the previous months. Blood samples were tested for SARS-CoV-2-specific immunoglobulin G using ELISA. The final population included 112 children, 24 siblings of these children, and 36 adults. The seroprevalence of cases was 6.9% before 8 September, a date that corresponds to 1 week after the beginning of the second wave in Belgium and 22.5% afterwards (OR = 3.89, 95% CI (1.20; 12.58), p-value = 0.03). Twenty-five percent of children were asymptomatic, and none experienced severe disease. The symptoms associated with SARS-CoV-2-positive antibodies were diarrhoea (OR = 9.9, 95% CI [2.88; 33.87.65] p-value < 0.01), fever (OR = 3.8, 95% CI [1.44; 10.22] p-value < 0.01), rhinitis (OR = 3.9, 95% CI [1.38; 10.90] p-value = 0.01), or anosmia (OR = 31.5, 95% CI [1.45; 682.7], p-value = 0.02). A child was the first symptomatic household member in 50% of the familial clusters.Conclusion: Seroprevalence in children was comparable to that of the general population. Children could represent the source of infection in the household. What is Known:• COVID-19 infection is generally mild or asymptomatic in children and adolescents.• Belgian strategy of testing was focused on symptoms.• Adults are believed to be responsible for most of familial clusters.What is New:• Serological testing gives a more accurate view of the rate of infected children.• Based on serological results, children have been infected as frequently as adults during the first and second wave in Belgium.• Seventy-five percent of SARS-CoV-2 IgG-positive children presented a mild symptomatology, and 25% were totally asymptomatic.• Children could represent the source of infection within household.

Dengue Outbreaks in Abidjan: Seroprevalence and Cocirculating of Three Serotypes in 2017

Dengue fever is a major public health problem in the world, because it is especially endemic in the tropical and subtropical areas. Arbovirus infection is less well documented in African countries. We aimed to assess the distribution of patients in the dengue epidemic and the seroprevalence of different serotypes of the circulating dengue virus. A retrospective study included analyses of human blood samples sent to the National Reference Laboratory for diagnosis during dengue infection outbreak. Samples were screened by IgM capture ELISA (MAC-ELISA) or by RT-PCR. Of the 2,849 serum samples from suspected dengue cases, 2,297 (80.6%) were from Abidjan. The seroprevalence of dengue was (15.1%) during this epidemic. The seroprevalence of dengue virus serotypes in cocirculation was predominated by DENV-2 with 189 cases (6.6%), followed by DENV-3 77 cases (2.7%), and DENV-1 14 cases (0.5%). The seroprevalence in children was 8.7% compared to 19.0% in adults. The age group of 16 to less than 45 years accounted for 54.0% of total positive cases. In addition, positive peak was observed in July (28.3%) and Abidjan East was the most affected locality. The increasing trend of serotypes of the dengue virus cocirculation suggests that Abidjan is becoming a hyperendemic state from an endemic one.

Detection of anti-M. leprae antibodies in children in leprosy-endemic areas: A systematic review.

BackgroundLeprosy elimination primarily targets transmission of Mycobacterium leprae which is not restricted to patients’ households. As interruption of transmission is imminent in many countries, a test to detect infected asymptomatic individuals who can perpetuate transmission is required. Antibodies directed against M. leprae antigens are indicative of M. leprae infection but cannot discriminate between active and past infection. Seroprevalence in young children, however, reflects recent M. leprae infection and may thus be used to monitor transmission in an area. Therefore, this literature review aimed to evaluate what has been reported on serological tests measuring anti-M. leprae antibodies in children without leprosy below the age of 15 in leprosy-endemic areas.Methods and findingsA literature search was performed in the databases Pubmed, Infolep, Web of Science and The Virtual Health Library. From the 724 articles identified through the search criteria, 28 full-text articles fulfilled all inclusion criteria. Two additional papers were identified through snowballing, resulting in a total of 30 articles reporting data from ten countries. All serological tests measured antibodies against phenolic glycolipid-I or synthetic derivatives thereof, either quantitatively (ELISA or UCP-LFA) or qualitatively (ML-flow or NDO-LID rapid test). The median seroprevalence in children in endemic areas was 14.9% and was stable over time if disease incidence remained unchanged. Importantly, seroprevalence decreased with age, indicating that children are a suitable group for sensitive assessment of recent M. leprae infection. However, direct comparison between areas, solely based on the data reported in these studies, was impeded by the use of different tests and variable cut-off levels.ConclusionsQuantitative anti-PGL-I serology in young children holds promise as a screening test to assess M. leprae infection and may be applied as a proxy for transmission and thereby as a means to monitor the effect of (prophylactic) interventions on the route to leprosy elimination.

Variation in SARS-CoV-2 seroprevalence across districts, schools and classes: baseline measurements from a cohort of primary and secondary school children in Switzerland

ObjectivesTo determine the variation in SARS-CoV-2 seroprevalence in school children and the relationship with self-reported symptoms.DesignBaseline measurements of a longitudinal cohort study (Ciao Corona) from June to July 2020.Setting55 schools...

High SARS-CoV-2 seroprevalence in children and adults in the Austrian ski resort of Ischgl

BackgroundIn early March 2020, a SARS-CoV-2 outbreak in the ski resort Ischgl in Austria initiated the spread of SARS-CoV-2 throughout Austria and Northern Europe.MethodsBetween April 21st and 27th 2020, a cross-sectional epidemiologic study targeting the full population of Ischgl (n = 1867), of which 79% could be included (n = 1473, incl. 214 children), was performed. For each individual, the study involved a SARS-CoV-2 PCR, antibody testing and structured questionnaires. A mathematical model was used to help understand the influence of the determined seroprevalence on virus transmission.ResultsThe seroprevalence was 42.4% (95% confidence interval (CI) 39.8–44.7). Individuals under 18 showed a significantly lower seroprevalence of 27.1% (95% CI 21.3-33.6) than adults (45%; 95% CI 42.2–47.7; OR of 0.455, 95% CI 0.356–0.682, p < 0.001). Of the seropositive individuals, 83.7% had not been diagnosed to have had SARS-CoV-2 infection previously. The clinical course was generally mild. Over the previous two months, two COVID-19-related deaths had been recorded, corresponding to an infection fatality rate of 0.25% (95% CI 0.03–0.91). Only 8 (0.5 %) individuals were newly diagnosed to be infected with SARS-CoV-2 during this study.ConclusionsIschgl was hit early and hard by SARS-CoV-2 leading to a high local seroprevalence of 42.4%, which was lower in individuals below the age of 18 than in adults. Mathematical modeling suggests that a drastic decline of newly infected individuals in Ischgl by the end of April occurred due to the dual impact from the non-pharmacological interventions and a high immunization of the Ischgl population.

Estimated SARS-CoV-2 Seroprevalence in Healthy Children and Those with Chronic Illnesses in the Washington Metropolitan Area as of October 2020.

The estimated severe acute respiratory syndrome coronavirus 2 seroprevalence in children was found to be 9.46% for the Washington Metropolitan area. Hispanic/Latinx individuals were found to have higher odds of seropositivity. While chronic medical conditions were not associated with having antibodies, previous fever and body aches were predictive symptoms.

ОСОБЕННОСТИ СЕРОПРЕВАЛЕНТНОСТИ К НУКЛЕОКАПСИДУ SARS-CоV-2 У ДЕТЕЙ В ПЕРИОД ЭПИДЕМИИ COVID-19 2020 ГОДА

The aim of the study is to summarize the results of a study of seroprevalence of children to SARS-CoV-3, obtained during the implementation of the Rospotrebnadzor program to assess seroprevalence to the NC antigen SARS-CoV-2 of the population of 26 regions of the Russian Federation, conducted during the COVID-19 epidemic in 2020. Research methods: the study of seroprevalence in 26 model territories of the Russian Federation was carried out according to a unified methodology developed by Rospotrebnadzor with the participation of the St. Petersburg Pasteur Institute of Epidemiology and Microbiology. The method provided for the formation of a group of volunteers in a model federative entity, including children aged 1–17 years, in which the presence of antibodies to the SARS-CoV-2 nucleocapsid was determined in venous blood plasma by the enzyme-linked immunosorbent assay (ELISA). The examination of volunteers was carried out in 3 stages: June-August, September-October, December. Results: the study found that in most of the areas surveyed, children had a higher level of seroprevalence than adults. It is shown that high seroprevalence is accompanied by statistically significant decrease in morbidity (p0.05). The analysis of seroprevalence at all three stages revealed at least 3 variants of its dynamics: 1) continuous growth of seroprevalence in parallel with the development of the epidemic process; 2) an episodic change in the periods of increase and decrease in the level of seroprevalence; 3) a continuous decrease in seroprevalence at the level of the epidemic process. Comparative determination of seroconversion levels in three age groups – 1–6, 7–13 and 14–17 years – revealed no statistically significant differences between these age groups have been identified. Conclusion: children aged 1–17 years in most of the surveyed territories of the Russian Federation have a higher seroprevalence to SARS-CoV2 than adults. The increase in seroprevalence in children is accompanied by a decrease in the incidence of COVID-19.

Toxoplasma gondii IgG seroprevalence in children with cancer from National Children's Antineoplastic Drug Program network in the Metropolitan Region, Chile: a multicenter study

Toxoplasma gondii is a protozoan that affects a third of the world population and whose updated seroprevalence in children with cancer in our environment is unknown. To describe the seroprevalence of IgG anti-T. gondii in pediatric population with cancer treated in hospitals of the Metropolitan Region, Chile. Cross-sectional study of the population of pediatric cancer patients treated in Santiago city, A serum sample was taken from 100 patients between June 2016 and May 2019. ELISA IgG T. gondii was performed. Of 100 children, 51% male. 12 were positive (12%), 84 negative (84%) and 4 indeterminate (4%). The stratification by age showed 43% patients between 0-5 years, 29% between 6-10 years, 20% in the group of 11-15 years and 8% in patients > 15 years. Sixty one percent of the samples came from patients with acute leukemia. The percentage of women who tested positive for IgG was 21% compared to 4% in men (P < 0.0011). 84% of children undergoing cancer treatment are seronegative for T. gondii, so it is important to educate on the prevention of the acquisition of this parasite in this population, due to the risk of developing serious and fatal disease.

SARS-CoV-2 transmission among children and staff in daycare centres during a nationwide lockdown in France: a cross-sectional, multicentre, seroprevalence study

BackgroundThe extent to which very young children contribute to the transmission of SARS-CoV-2 is unclear. We aimed to estimate the seroprevalence of antibodies against SARS-CoV-2 in daycare centres that remained open for key workers' children during a nationwide lockdown in France.MethodsChildren and staff who attended one of 22 daycare centres during a nationwide lockdown in France (between March 15 and May 9, 2020) were included in this cross-sectional, multicentre, seroprevalence study. Hospital staff not occupationally exposed to patients with COVID-19, or to children, were enrolled in a comparator group. The primary outcome was SARS-CoV-2 seroprevalence in children, daycare centre staff, and the comparator group. The presence of antibodies against SARS-CoV-2 in capillary whole blood was measured with a rapid chromatographic immunoassay. We computed raw prevalence as the percentage of individuals with a positive IgG or IgM test, and used Bayesian smoothing to account for imperfect sensitivity and specificity of the assay. This study is registered with ClinicalTrials.gov, NCT04413968.FindingsBetween June 4 and July 3, 2020, we enrolled 327 children (mean age 1·9 [SD 0·9] years; range 5 months to 4·4 years), 197 daycare centre staff (mean age 40 [12] years), and 164 adults in the comparator group (42 [12] years). Positive serological tests were observed for 14 children (raw seroprevalence 4·3%; 95% CI 2·6–7·1) and 14 daycare centre staff (7·7%; 4·2–11·6). After accounting for imperfect sensitivity and specificity of the assay, we estimated that 3·7% (95% credible interval [95% CrI] 1·3–6·8) of the children and 6·8% (3·2–11·5) of daycare centre staff had SARS-CoV-2 infection. The comparator group fared similarly to the daycare centre staff; nine participants had a positive serological test (raw seroprevalence 5·5%; 95% CI 2·9–10·1), leading to a seroprevalence of 5·0% (95% CrI 1·6–9·8) after accounting for assay characteristics. An exploratory analysis suggested that seropositive children were more likely than seronegative children to have been exposed to an adult household member with laboratory-confirmed COVID-19 (six [43%] of 14 vs 19 [6%] of 307; relative risk 7·1 [95% CI 2·2–22·4]).InterpretationAccording to serological test results, the proportion of young children in our sample with SARS-CoV-2 infection was low. Intrafamily transmission seemed more plausible than transmission within daycare centres. Further epidemiological studies are needed to confirm this exploratory hypothesis.FundingAssistance Publique—Hôpitaux de Paris; Mairie de Paris, Conseil Départemental de Seine Saint Denis.TranslationsFor the French translation of the abstract see Supplementary Materials section.

Prevalence and Susceptibility to SARS-CoV-2 in Children

Source: Viner RM, Mytton OT, Bonell C, et al. Susceptibility to SARS-CoV-2 infection among children and adolescents compared with adults: a systematic review and meta-analysis [published online ahead of print September 25, 2020]. JAMA Pediatrics. doi: 10.1001/jamapediatrics.2020.4573Investigators from multiple institutions conducted a systematic review and meta-analysis to determine the susceptibility to, and transmission of, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in children and adolescents compared to adults. Investigators searched PubMed and the medical preprint server medRxiv for articles published through July 28, 2020. Studies that provided data on proven SARS-CoV-2 infection and reported either rate of secondary infections in children and adolescents compared to adults (contact-tracing studies) or infection prevalence or seroprevalence in children and adolescents separate from adults (prevalence studies) were included. Studies that reported single-institution outbreaks or only included children were excluded.Identified studies were reviewed for eligibility by 2 investigators. Methodological quality of included studies (categorized as high, medium, low, or uncertain) was assessed independently by 3 investigators, with risk of bias assessed as whether symptomatic contacts or individuals were more likely to participate than asymptomatic ones and whether the obtained sample was >75% of the intended sample. Among included contact-tracing studies, investigators combined data on children and adolescents <20 years old and compared these data with those from adults ≥20 years old, generating pooled odds ratio (OR) estimates of being a child with secondary infections compared with being an adult. Subgroup analyses of contact-tracing studies were performed by child age (<10 years, 10-19 years) compared to adults. Data from prevalence studies was not pooled given heterogeneity among populations and reported as ratios of prevalence of SARS-CoV-2 infection in children compared to adults.There were 32 studies included in analysis involving 41,640 children and adolescents and 268,945 adults. Among included studies, 18 were contact-tracing studies and 14 were prevalence studies. Only 2 studies were determined to be high quality.The pooled OR for all contact-tracing studies was 0.56 (95% CI, 0.37, 0.85), suggesting reduced odds of secondary infections among children compared to adults. For children <10 years old, the pooled OR was 0.52 (95% CI, 0.33, 0.82). In the 14 prevalence studies, the ratios of SARS-CoV-2 prevalence in children and adolescents compared to adults ranged from 0.07 to 0.97, suggesting lower prevalence in children.The authors conclude that children and adolescents have lower odds of being an infected contact and have a lower prevalence of SARS-CoV-2 compared to adults.Dr Brady has disclosed no financial relationship relevant to this commentary. This commentary does not contain a discussion of an unapproved/investigative use of a commercial product/ device.A total of 792,188 COVID-19 cases in children were reported in the US through October 22, 2020.1 The overall rate has been 1,053 cases per 100,000 children. Children have accounted for 0% to 0.23% of all COVID-19 deaths. Most children with COVID-19 have mild symptoms and a good prognosis. (See AAP Grand Rounds. 2020;44[1]:52 and AAP Grand Rounds. 2020;44[4]:42.3)The current investigators found that children had an OR of 0.56 for being an infected contact compared to adults. Explanations that have been suggested for this lower susceptibility among children include fewer underlying medical conditions, healthier respiratory tracts, and stronger innate immune responses.4,5 A biologically plausible theory also concerns expression of the angiotensin converting enzyme 2 (ACE2) receptor used by SARS-CoV-2 to enter the nasal epithelial cell, usually the first point of contact between the virus and the human body.6 Children have lower ACE2 gene expression in the nasal epithelium as compared to adults, which may decrease infectivity.7The current investigators were not able to determine whether transmission of SARS-CoV-2 by children was lower compared to adults. Three school-based contact-tracing studies found minimal transmission from child or teacher index cases. Population screening studies were not suitable for meta-analysis to compare transmission events between children and adults. A large prospective NIH-funded study of 6,000 people from 2,000 US families in 11 cities, called Human Epidemiology and Response to SARS-CoV-2 (HEROS),8 is in progress to clarify the role of children in the transmission of this novel coronavirus. Wearing masks and social distancing are still best practices.Current evidence suggests that children have a lower susceptibility to SARS-CoV-2 infection and a lower prevalence compared to adults. The role that children play in transmission remains unclear.While we focus, appropriately, on SARS-CoV-2, emerging data suggest that coinfection with other respiratory pathogens may be relatively common in children;9 thus the importance of screening for both SARS-CoV-2 as well as other respiratory pathogens.

Seroprevalence of Mumps in Healthcare Workers in South Korea

Background: Mumps, a contagious disease, is transmissible by respiratory droplet particles and is preventable by vaccination. In South Korea, mandatory vaccination against mumps has markedly reduced its incidence. However, both the incidence and the number of reported cases of mumps have persistently increased in South Korea since 2007. Despite high vaccination rates, mumps outbreaks continue to occur, and many studies have been conducted on mumps seroprevalence in children and adolescents. In comparison, few reports have been published regarding mumps seroprevalence in healthcare workers (HCWs) in South Korea. Objective: We investigated the seroprevalence of HCWs in South Korea. Methods: This study was conducted at Asan Medical Center, a 2,705-bed tertiary-care hospital in Seoul, South Korea, with 8,329 HCWs. In 2018, we performed mumps antibody testing for HCWs. We administered MMR vaccination to all HCWs whose antibody test yielded equivocal or negative results. However, we did not repeat mumps antibody testing after MMR vaccination. Results: In total, 6,055 HCWs (73%) underwent mumps antibody testing. The overall mumps seropositivity rate was 87% (95% CI, 86%–87%). Seropositivity rates of all birth cohorts ranged from 72% to 92%. Mumps seropositivity rates were 88% in HCWs born before 1970, 87% in those born between 1970 and 1989, and 88% in those born between 1990 and 1995 (P = .59). Mumps seropositivity rates for both women and men HCWs were 87% (3,770 of 4,311 women and 1,517 of 1,744 men); the difference was not statistically significant (P = .62). The overall mumps seropositivity rate was 87%, which was above the herd immunity threshold of 75%–86%. Conclusions: Our results revealed that the overall mumps seropositivity rate in South Korean HCWs was above the herd immunity threshold. On the basis of this finding, we recommend that MMR vaccination after serologic testing may be a more reasonable approach than universal MMR vaccination alone in Korea.Funding: NoneDisclosures: None

Susceptibility to SARS-CoV-2 Infection Among Children and Adolescents Compared With Adults

The degree to which children and adolescents are infected by and transmit severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is unclear. The role of children and adolescents in transmission of SARS-CoV-2 is dependent on susceptibility, symptoms, viral load, social contact patterns, and behavior. To systematically review the susceptibility to and transmission of SARS-CoV-2 among children and adolescents compared with adults. PubMed and medRxiv were searched from database inception to July 28, 2020, and a total of 13 926 studies were identified, with additional studies identified through hand searching of cited references and professional contacts. Studies that provided data on the prevalence of SARS-CoV-2 in children and adolescents (younger than 20 years) compared with adults (20 years and older) derived from contact tracing or population screening were included. Single-household studies were excluded. PRISMA guidelines for abstracting data were followed, which was performed independently by 2 reviewers. Quality was assessed using a critical appraisal checklist for prevalence studies. Random-effects meta-analysis was undertaken. Secondary infection rate (contact-tracing studies) or prevalence or seroprevalence (population screening studies) among children and adolescents compared with adults. A total of 32 studies comprising 41 640 children and adolescents and 268 945 adults met inclusion criteria, including 18 contact-tracing studies and 14 population screening studies. The pooled odds ratio of being an infected contact in children compared with adults was 0.56 (95% CI, 0.37-0.85), with substantial heterogeneity (I2 = 94.6%). Three school-based contact-tracing studies found minimal transmission from child or teacher index cases. Findings from population screening studies were heterogenous and were not suitable for meta-analysis. Most studies were consistent with lower seroprevalence in children compared with adults, although seroprevalence in adolescents appeared similar to adults. In this meta-analysis, there is preliminary evidence that children and adolescents have lower susceptibility to SARS-CoV-2, with an odds ratio of 0.56 for being an infected contact compared with adults. There is weak evidence that children and adolescents play a lesser role than adults in transmission of SARS-CoV-2 at a population level. This study provides no information on the infectivity of children.

High risk of mumps infection in children who received one dose of mumps-containing vaccine: waning immunity to mumps in children aged 2-5 years from kindergartens in Jiangsu Province, China

ABSTRACT Background During the period of immunization with a single-dose measles-mumps-rubella (MMR) vaccine, which has been available since 2008in China, the incidence of mumps in children aged 2–5 years has been high. The aim of this study was to determine the immunity profile of mumps in children aged 2–5 years as part of the assessment of the MMR vaccination strategy. Methods A cross-sectional survey of IgG antibodies against mumps virus in children aged 2–5 years was performed. Analysis by enzyme-linked immune sorbent assay(ELISA)was performed to measure IgG antibodies against mumps virus in the sera of 2-to5-year-old children who had been vaccinated with at least one dose of MMR vaccine. Results Mumps outbreaks mainly occurred in kindergarten and primary schools and primarily involved children in kindergarten from 2015-2016 in Jiangsu Province. In total, 4,033 children were surveyed. The overall seroprevalence of mumps antibodies was 79.0% (95% CI:78.4–79.6), and the geometric mean concentration (GMC) was 323.6 mIU/ml (309.0–338.8). Both univariate and multivariate survival analysis of seroprevalence showed that several factors contributed to having significant seroprevalence among the 2-to-5-year-old group (P < .05). The seroprevalence of children with a single-dose MMR vaccine regimen (78.4%, 95% CI: 77.8–80.4) was significantly lower than that of children with a two-dose MMR vaccine regimen (96.5%, 95% CI: 88.6%-96.1%). The seroprevalence rate was negatively correlated with time since inoculation (P < .01). Conclusion Children who received a single dose of MMR vaccine in kindergarten, particularly the 2-year-old group in the northern region of Jiangsu Province, China, are at high risk of mumps infection. Our study demonstrates thata single-dose MMR vaccine regimen has a limited effect on controlling mumps, which highlights the benefit of introducing a two-dose MMR vaccine schedule.