5歳未満ではSARS-CoV-2の排泄が多い

アメリカから残念な報告が出てきました。

5歳未満ではSARS-CoV-2のウイルス排泄が成人の数十倍と多いことが報告されました。

中国でも5歳未満ではCoVID-19に伴った重症の肺炎が7％と、比較的若い成人よりも効率に起こっていることが報告されていましたが、同様に他人への感染リスクも高く、クラスターを作りうるようです。

5歳以上では、成人と同レベルで、重い肺炎は成人よりも起きにくいのですが、やはりクラスターを作る可能性があります。

（※　管理者注　2020/08/19記載）

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軽度から中等度のコロナウイルス病患者における鼻咽頭SARS-CoV-2レベルの年齢関連の違い。

子どもはSARS-CoV-2に感染しやすいですが、一般的には成人と比較して軽度の症状を示します。 SARS-CoV-2拡散はまばらです。

初期の報告では、SARS-CoV-2感染の主な原因としての子供たちの強力な証拠は見つかりませんでした。

しかし、パンデミックへの対応の早い段階での学校閉鎖は、コミュニティの感染源としての学校の大規模調査を妨害しました。

公衆衛生システムが学校やデイケアを再開することを期待しているため、公衆衛生対策を導くためには、子どもの感染の可能性を理解することが重要です。

ここでは、年長の子供におけるSARS-CoV-2の複製が成人と同様のレベルのウイルス核酸につながることを報告しますが、5歳未満の子供では大幅に多くの量のウイルス核酸が検出されます。

私たちの最後のコホートには、症状の発症から1週間以内に軽度から中程度の病気の145人の患者が含まれていました。

3つのグループ：5歳未満の幼児（n = 46）、5〜17歳（n older = 51）、18〜65歳の成人（n = 48）を比較しました。

年長の子ども（11.1 [6.3-15.7]）と大人（11.0 [6.9-17.5]）の同様の中央値（四分位範囲）CT値が見つかりました。

ただし、幼児のCT値の中央値（四分位範囲）は有意に低く（6.5 [4.8-12.0]）、幼児が上気道に同等以上のウイルス核酸を持っていることを示しています。

幼児と成人の間のCT値の中央値で観察された違いは、幼児の上気道におけるSARS-CoV-2の量がおよそ10倍から100倍ほど多いことを示しています。

感度分析を行い、症状の持続期間が不明なグループを含めた場合、グループ間で同様の統計的差異を観察しました。

さらに、全体的なコホート（スピアマンρ= 0.22）と各サブグループ（幼児、スピアマンρ= 0.20;年長児、スピアマンρ= 0.19）;および成人、（スピアマンρ= 0.10）の症状期間とCTの間の非常に弱い相関のみを特定しました。

Age-Related Differences in Nasopharyngeal Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Levels in Patients With Mild to Moderate Coronavirus Disease 2019 (COVID-19)

Taylor Heald-Sargent, MD, PhD; William J. Muller, MD, PhD; Xiaotian Zheng, MD, PhD; et al

JAMA Pediatr. Published online July 30, 2020. doi:10.1001/jamapediatrics.2020.3651

https://jamanetwork.com/journals/jamapediatrics/fullarticle/2768952

Children are susceptible to infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) but generally present with mild symptoms compared with adults.¹ Children drive spread of respiratory and gastrointestinal illnesses in the population,² but data on children as sources of SARS-CoV-2 spread are sparse.

Early reports did not find strong evidence of children as major contributors to SARS-CoV-2 spread,³ but school closures early in pandemic responses thwarted larger-scale investigations of schools as a source of community transmission. As public health systems look to reopen schools and day cares, understanding transmission potential in children will be important to guide public health measures. Here, we report that replication of SARS-CoV-2 in older children leads to similar levels of viral nucleic acid as adults, but significantly greater amounts of viral nucleic acid are detected in children younger than 5 years.

Methods

Between March 23 and April 27, 2020, we performed SARS-CoV-2 reverse transcriptase–polymerase chain reaction (PCR) on nasopharyngeal swabs collected at various inpatient, outpatient, emergency department, and drive-through testing sites at a pediatric tertiary medical center in Chicago, Illinois. The Ann & Robert H. Lurie Children’s Hospital of Chicago Institutional Review Board provided an exemption and full waiver of HIPAA authorization and informed consent. A Clinical Laboratory Improvement Amendments–certified laboratory analyzed samples using a US Food and Drug Administration Emergency Use Authorization PCR assay (Abbot RealTime SARS-CoV-2 Assay performed on the m2000 RealTime System [Abbott Laboratories]). PCR amplification cycle threshold (CT) values were recorded, with lower values indicating higher amounts of viral nucleic acid.

This cohort included all individuals aged younger than 1 month to 65 years who tested positive for SARS-CoV-2. Patients with symptoms suggestive of a COVID-19–compatible illness and/or high-risk exposures were tested. We included the first sample tested for patients with multiple samples. Because patients with severe infection have lower CT values,⁴ we excluded 7 children who required supplemental oxygen support. We also excluded 7 asymptomatic patients, 29 patients with unknown duration of symptoms, and 19 patients whose symptoms started more than 1 week prior to testing. Swabs were collected using a standard bilateral nasopharyngeal sampling procedure. Several controls, including samples with known copy numbers, were included in each PCR run. Median and interquartile ranges for each group were measured and compared using the nonparametric Wilcoxon rank sum test. Two-sided P values less than .05 were considered statistically significant. Analyses were performed using Stata/IC statistical software version 16.0 (StataCorp).

Results

Our final cohort included 145 patients with mild to moderate illness within 1 week of symptom onset. We compared 3 groups: young children younger than 5 years (n = 46), older children aged 5 to 17 years (n = 51), and adults aged 18 to 65 years (n = 48). We found similar median (interquartile range) CT values for older children (11.1 [6.3-15.7]) and adults (11.0 [6.9-17.5]). However, young children had significantly lower median (interquartile range) CT values (6.5 [4.8-12.0]), indicating that young children have equivalent or more viral nucleic acid in their upper respiratory tract compared with older children and adults (Figure). The observed differences in median CT values between young children and adults approximate a 10-fold to 100-fold greater amount of SARS-CoV-2 in the upper respiratory tract of young children. We performed a sensitivity analysis and observed a similar statistical difference between groups when including those with unknown symptom duration. Additionally, we identified only a very weak correlation between symptom duration and CT in the overall cohort (Spearman ρ = 0.22) and in each subgroup (young children, Spearman ρ = 0.20; older children, Spearman ρ = 0.19; and adults, Spearman ρ = 0.10).