1) What does it mean when study findings are ‘potentially confounded’? Explain exactly what authors meant when they said, “Epidemiologic studies suggest that children exhibit lower transmission rates

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1) What does it mean when study findings are ‘potentially confounded’? Explain exactly what authors meant when they said, “Epidemiologic studies suggest that children exhibit lower transmission rates than adults, however, these findings are potentially confounded by higher rates of asymptomatic or pauci-symptomatic infection in children, increased social isolation by children early in the pandemic, and reduced COVID-19 testing in children.” How can each of these confounding factors lead to results that suggest children exhibit lower transmission rates?

2) Why do you think authors were interested in showing their data in slightly different ways, plots Figures 1A-D? What question does each plot uniquely answer?

3) Why did authors conduct viral culture assays for recoverable SARS-Co-V-2 in parallel with viral load testing? [What additional information do authors gain by doing both?]

4) What’s the significance of Fig. 2B? Explain the groups on the x-axis, and the y-axis. Then explain how to interpret the data.

5) What does Fig. 4A signify and why did authors analyze their data in this way?

6) Which COVID variants were found among the subjects in this study? Why were the authors motivated to sequence the genomes of the cultured viruses from their subjects?

1) What does it mean when study findings are ‘potentially confounded’? Explain exactly what authors meant when they said, “Epidemiologic studies suggest that children exhibit lower transmission rates
Virologic features of SARS -CoV -2 infection in children 1 2 Lael M. Yonker 1,2,3 *, Julie Boucau 4*, James Regan 5, Manish C. Choudhary 3,5, M adeleine D. 3 Burns 1, Nicola Young 1, Eva J . Farkas 1, Jameson P. Davis 1, Peter P. Moschovis 2,3, T. Bernard 4 Kinane 2,3, Alessio Fasano 1,2,3 , Anne M. Neilan 2,3,6 , Jon athan Z. Li 3,5*, Amy K. Barczak 3,4,6 * 5 6 1. Massachusetts General Hospital, Mucosal Immunology and Biology Research Center, 7 Boston, MA, USA 8 2. Massachusetts General Hospital, Department of Pediatrics, Boston, MA, USA 9 3. Ha rvard Medical School, Boston, MA, USA 10 4. Ragon Institute of MGH , MIT and Harvard, Cambridge, MA, USA 11 5. Brigham and Women’s Hospital, Department of Medicine , Boston, MA, USA 12 6. Massachusetts General Hospital, Department of Medicine, Boston, MA, USA 13 14 *Authors contributed equally 15 16 Correspondence : 17 Lael Yonker: Massachusetts General Hospital, 55 Fruit St, Jackson 14, Boston, MA 02114. 18 617 -724 -2890. [email protected] 19 20 Word c o u nt a b str a ct: 200 21 Wo rd c o u nt m ain t e x t: 2 89 4 22 23 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 17, 2021. ; https://doi.org/10.1101/2021.05.30.21258086 doi: medRxiv preprint NOTE: This preprint reports new research that has not been certified by peer review and should not be used to guide clinical practice. Abstract 24 Background : Data on pediatric COVID -19 has lagged behind adults throughout the pandemic . 25 An understanding of SARS -CoV -2 viral dynamics in children would enable data -driven public 26 health guidance. 27 Methods : Respiratory swabs were collected from children with COVID -19 . Viral load was 28 quantified by RT -PCR ; viral culture was assessed by direct observation of cytopathic effects and 29 semiquantitative viral titers . C orrelation s with age , symptom duration , and disease severity were 30 analyzed . SARS -CoV -2 whole genome sequences were compared with contemporaneous 31 sequences . 32 Results : 110 children with COVID -19 (median age 10 years , range 2 weeks -21 years) were 33 included in this study. Age did not impact SARS -CoV -2 viral load . Children were most infectious 34 within the first five days of illness , and severe disease did not correlate with increased viral 35 loads. Pediatric SARS -CoV -2 sequences were representative of those in the community and 36 novel variants were identified . 37 Conclusions : Symptomatic and asymptomatic c hildren can carry high quantities of live, 38 replicating SARS -CoV -2, creating a potential reservoir for transmission and evolution of genetic 39 variants. As guidance around social distancing and masking evolves following vaccine uptake in 40 older populations , a clear understanding of SARS -CoV -2 infection dynamics in children is critical 41 for rational development of public health policies and vaccination strategies to mitigate the 42 impact of COVID -19. 43 44 45 Keywords: SARS -CoV -2, Pediatric COVID -19, Viral dynamics 46 47 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 17, 2021. ; https://doi.org/10.1101/2021.05.30.21258086 doi: medRxiv preprint Background 48 Since the SARS -CoV -2 virus ignited the COVID -19 global pandemic, the impact of the virus on 49 children and the role that children pla y in this pandemic has been understudied. I nitially , 50 epidemiology reports suggested that children may have been relatively spared from infection , 51 however, as COVID -19 testing became more available, it has been increasingly recognized that 52 children can be infected with SARS -CoV -2 at rates comparable to adults [1, 2] . To date , over 53 4.1 million children in the Unites States have been reported as testing positive for COVID -19 [3] . 54 Since the winter of 20 20 -20 21, children under 19 years of age have represented one of the age 55 groups with the highest rates of infection [4] , which likely reflects a combination of increased 56 number of infections among children plus increased vaccination rates amongst adults . Most 57 children generally have milder symptoms when infected with SARS -CoV -2 [5] , although a small 58 subset of individuals develop severe diseas e. In the US, over 16,000 children have been 59 hospitalized for acute COVID -19 with over 300 deaths reported [3] . A baseline understanding of 60 the viral characteristics of SARS -CoV -2 infection in children is a necessary prerequisite to 61 understanding the pathogenesis of severe presentations of COVID -19 [6] . 62 At a population perspective, the role that children play in viral transmission remains poorly 63 unders tood. Epidemiologic studies suggest that children exhibit lower transmission rates than 64 adults [7] , however, these findings are potentially confounded by higher rates of asymptomatic 65 or pauci -symptomatic infection in children, increased social isolation by children early in the 66 pandemic, and reduced COVID -19 testing in children. To date, one small study demonstrated 67 that live virus can be cultured from children [8] . However, t he types of systematic studies that 68 ha ve informed our understanding of the viral dynamics of SARS -CoV -2 in adult populations [9- 69 11] have not similarly been carried out in children . As vaccination has become available for 70 adults and adolescents in many places in the world and our understanding of transmission 71 dynamics ha ve evolved , masking and distancing policies are being relaxed [12] . Policy changes 72 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 17, 2021. ; https://doi.org/10.1101/2021.05.30.21258086 doi: medRxiv preprint have necessarily been made despite the paucity of data providing insight into the role that 73 pediatric disease might play in ongoing transmission. As viral variants that enhance the potential 74 for transmission and/ or reduce vaccine efficacy emerge [13 -15] , the importance of identifying 75 potential reservoirs of viral replication and transmission has been brought into the spotlight . 76 Defining the virologic features of SARS -CoV -2 infection in children and the potential for children 77 to transmit virus will facilitate rational public health decision -making for pediatric populations. 78 In this work, we sought to define fundamental virologic features of SARS -CoV -2 in a pediatric 79 population across a range of disease severity . W e analyzed respiratory swabs from children 80 presenting to urgent care clinics or the hospital with symptomatic and asymptomatic COVID -19 81 infection . Clinical factors, such as age, C OVID -19 risk factors, and disease severity were 82 compared with viral features including SARS -CoV -2 viral load, isolation of replication -competent 83 virus, and whole viral sequenc ing . Our data indicate that age , from infancy through adulthood, is 84 not a predict or of viral infection dynamics, and that children of all ages can have high SARS – 85 CoV -2 viral loads of replication -competent virus, including variants, displaying comparable 86 dynamics to those seen in adults. 87 88 Methods 89 Sample collection 90 Infants, children and adolescents <21 years of age presenting to Massachusetts General 91 Hosp it a l u rg en t c a re c lin ic s o r th e h o sp it a l wi th ei ther sym ptom s concer ning for or know n 92 exposur e to CO VID -19 (4/202 0 -4/ 2021) were pr ospect ivel y offer ed enr ollm ent in t he Inst it ut ional 93 Revie w Bo ard -appr oved MGH P edi atric CO VID -19 Bior eposi tor y (IR B # 2020P 000955) [16] . 94 Af te r in fo rm ed c o nse nt, a nd a sse nt w he n a pp ro p ria te , w as o bta in ed v e rb al ly, a re se arc h - 95 desi gnat ed swab of the nasophar yn x, oroph ary n x and/ or ant erior nar es was o b ta in ed and 96 pl aced in phosphat e buf fer ed saline. Sample s we re a liq uote d a nd s to re d a t -80 oC. Sa mple s 97 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 17, 2021. ; https://doi.org/10.1101/2021.05.30.21258086 doi: medRxiv preprint from patients who tested positive for COVID -19 on clinical SARS -CoV -2 RT -PCR testing were 98 analyzed . Nasal samples from adults hospitalized with acute COVID -19 [10] (4/2020 -8/2020; 99 enrolled in Institutional Review Board -approved MGH COVID -19 Biorepository, IRB # 100 2020P000804) with duration of symptoms equal to the hospitali zed pediatric cohort were 101 selected for comparative studies. 102 103 Clinical data collection 104 Demographic and clinical factors were recorded through a combination of manual chart reviews 105 and data extraction from electronic health records (EHR) , then collected in a R EDC ap database 106 [17] through the Partners Electronic Health Record Registry of Pediatric COVID -19 Disease 107 (IRB # 2020P003588) . Trained reviewers collected demographics, SARS -CoV -2 risk factors, 108 comorbid conditions, medications, COVID -19 related symptoms, and laboratory tests. Outcome 109 of initial presentation to care, admission status, and complications of COVID -19 disease were 110 also extracted by manual review. 111 112 SARS -CoV -2 viral load quantification 113 Virions were pelleted from anterior nasal, oropharyngeal, and nasopharyngeal swab fluids by 114 centrifugation at approximately 21,000 x g for 2 hours at 4°C. RNA was extracted using Trizol - 115 LS (Thermofisher) according to the manufacturer’s instructions. RNA wa s then concentrated by 116 isopropanol precipitation , and SARS -CoV -2 RNA was quantified using the CDC N1 primers and 117 probe [ https://www.cdc.gov/coronavirus/2019 -ncov/ lab/rt -pcr -panel -primer -probes.html ] as 118 previ ousl y descr ibed [1 0] . As t h e re wa s n o s ig n if ic a nt d if fe re nce in v ir a l lo a d fr o m r e sp ir a to ry 119 secr etions obt ained fr om t he anterior nar es, nasophar ynx or or ophar ynx of par tici pant s 120 (Suppl em ent al Fi gur e 1 ), s am ple s w ere analy ze d to ge th er, re ga rd le ss o f c oll e cti o n s ite . 121 122 Vi ra l Cul tur e 123 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 17, 2021. ; https://doi.org/10.1101/2021.05.30.21258086 doi: medRxiv preprint Vero -E6 cells (ATCC) were maintained in D10+ media [Dulbec co’s modified Eagle’s media 124 (DMEM) ( Corning ) supplemented with HEPES ( Corning ), 1X Penicillin/Streptomycin ( Corning ), 125 1X Glutamine (Glutamax, Thermo Fisher Scientific ) and 10% Fetal Bovine serum (FBS) (Sigma)] 126 in a humidified incubator at 37 oC in 5% CO2. Vero -E6 cells were passaged every 3 -4 days, 127 detached using Trypsin -EDTA (Fisher Scientific) and seeded at 150,000 cells per wells in 24 128 well plates for culture experiments and 20,000 cells per well in 96w plates the day before 129 inoculation for median tissue cultur e infectious dose ( TCID50 ) experiments. 130 131 After thawing, each specimen was filtered through a Spin -X 0.45 µm filter (Corning) at 10,000 x g 132 for 5min. 50 µL of the supernatant was then diluted in 450 µL of D + media [DMEM supplemented 133 with HEPES, 1X Penicillin/Streptomycin and 1X Glutamine]. The viral culture experiments were 134 performed as previously reported [18] with the following modifications: 100 µL of the solution was 135 used to inoculate wells in a 24 well plate and 1mL of D 2+ media [D+ media with 2% FBS] was 136 added to each well after 1 hour of incubation . The plates were then placed in a 5% CO2 137 incubator at 37 oC. For TCID50 measurements conducted in parallel , 25 µL of the Spin -X flow - 138 through was used to inoc ulate Vero -E6 cells in a 96 well plate in the presence of 5 µg/mL of 139 polybrene (Santa Cruz Biotechnology) using 5 -fold dilutions (5 -1 to 5 -6) and 4 repeats for each 140 sample. The plates were centrifuged for 1 hour at 2,000 x g at 37 oC before being placed in a 5% 141 CO2 incubator at 37 oC. The SARS -CoV -2 isolate USA -WA1/2020 strain (BEI Resources) was 142 used as a positive control for CPE in both culture and TCID50 experiments. 143 144 Vira l c u lt u re a nd TCI D50 p la te s we re o bse rv e d a t 3 - and 6 -days post -infe ctio n w it h a lig ht 145 mi cro sc o p e a nd w ell s s h ow in g C PE w ere c o unte d . Th e TCI D50 tit e rs we re c a lc u la te d u sin g t h e 146 Sp ea rm an -Ka rb er m eth o d. Fo r th e c u lt u re p la te s, th e s u pe rn ata nt o f t h e we ll s d is p la yin g CPE 147 wa s h a rv e ste d 1 0 -14 days post -infe ctio n a n d R N A w as is ola te d usi ng a QIA am p Vir al R NA M ini 148 kit ( Q IA G EN ) for conf ir m at ion of t he viral sequence. 149 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 17, 2021. ; https://doi.org/10.1101/2021.05.30.21258086 doi: medRxiv preprint 150 SARS -CoV -2 sequencing 151 cDNA synthesis was performed using Superscript IV reverse transcriptase (Invitrogen). Whole 152 viral amplification was performed with the Artic protocol using multiplexed primer pools designed 153 with Primal Scheme generating 400 -bp tiling amplicons [19, 20] . PCR products were pooled and 154 Illumina library construction was performed using the Nextera XT Library Prep Kit (Illumina). The 155 comparison dataset included 183 representative contemporaneous SARS -CoV -2 genomes from 156 Massachusetts present in GISAID to assess for local clustering. Nucleotide sequence alignment 157 was performed with MAFFT (multiple alignment using fast Fourier transform) [21] . Best -fit 158 nucleotide substitution GTR+G+I was used for the datasets using model selection in IQ -Tree 159 followed by maximum likelihood phylogenetic tree construction usi ng IQ -Tree web server with 160 1000 -bootstrap replicates [22] . 161 162 Analysis 163 All statistical analyses were perfo rmed using p arametric comparisons in GraphPad Prism 164 (Version 9.1.1), including Pearson correlation, ANOVA with multiple comparisons , and unpaired 165 t test. 166 167 Results 168 Clinical cohort 169 One -hundred -ten children diagnosed with COVID -19 with a mean age of 10 years (range 0-21 170 years ) were included in the study (Table 1 ). There were slightly more boys (56%) than girls 171 (44%) with SARS -CoV -2 infection included in our analyses . One third of the participants were 172 White ( 33 %), 10% African American/Black, and 4% were Asian; one third (38%) reported their 173 ethnicity as Hispanic. Past medical history in children is reported in Supplemental Table 1 . 174 Thirty children were asymptomatic but were identified as having COVID -19: twenty -six children 175 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 17, 2021. ; https://doi.org/10.1101/2021.05.30.21258086 doi: medRxiv preprint (27%) presented to urgent care /COVID -19 testing sites because of a COVID -19 exposure , while 176 four children ( 4%) were identified on routine screening during hospital admission. Eight (7%) 177 presented with COVID -19 symptoms but had no known COVID -19 contact. The majority of 178 participants with COVID -19 did not require hospitalization (72 children, 65%) . Thirty -six children 179 (33%) were hospitalized with COVID -19, although only 1 8 children (1 6%) required supplemental 180 oxygen and/or invasive or non -invasive respir atory suppor t (referred to as “moderate/severe 181 COVID -19”) . 182 183 Age did not impact SARS -CoV -2 viral load or recovery of replication competent virus 184 Age is a well -established risk factor for developing severe COVID -19. Accordingly, 185 asymptomatic patients were significantly younger than patients with mild disease, and pediatric 186 patients who were hosp italized with hypoxemia were significantly older than asymptomatic 187 children or children with mild disease (Figure 1A ). However, viral load was not increased in 188 more severe disease: asymptomatic children and children with mild disease displayed 189 significantly higher viral loads than adults hospitalized with COVID -19 with comparable duration 190 of symptoms (less than 10 days) (Figure 1B ). However, there were no differences in viral load 191 between pediatric patients hospitalized with moderate/severe dis ease and hospitalized adults of 192 similar duration of illness (Figure 1B ) (Adult demographics are detailed in Supplemental Table 193 2). 194 195 The a ge of each infected child was analyzed to determine whether age impacted viral load . 196 There was no significant correlation of age with viral load ( Figure 1C ), nor were there significant 197 differences between ages when grouped by school levels : 0-4 years (infant through pre -school), 198 5-10 years (elementary school), 11 -16 years (middle school), 17 and older (high school and 199 higher education) (ANOVA, P = 0.12) (Figure 1 D). Thus , a child’s age did not appear to impact 200 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 17, 2021. ; https://doi.org/10.1101/2021.05.30.21258086 doi: medRxiv preprint viral load: all children , from 2 weeks through 2 1 years of age , were equally capable of carrying a 201 high viral load. 202 203 As SARS -CoV -2 RNA detection by RT -PCR does not specify whether replication -competent 204 virus is being shed, we next sought to ascertain risk factors for shedding live virus by performing 205 viral culture assays for recoverable SARS -CoV -2 in parallel with viral load testing . From the 110 206 participants , we collected 126 samples ; live virus was cultured from 33 samples coming from 32 207 participants . Of note, eight of these children with cultur able SARS -CoV -2 were asymptomatic. 208 Higher viral load was significantly predictive of shedding of live virus (t test, P < 0.0001) ( Figure 209 2A ). Consistent with the results for viral load, age was not correlated with viral culture results; 210 virus was recovered from children ages 1 month t hrough 21 years (Figure 2B ). Semi - 211 quantitative assessment of the amount of virus shed by an individual participant was assessed 212 by media n tissue culture infectious dose (TCID50). TCID50 for culture -positive specimens 213 correlated strongly with viral load (Pearson correlation r = 0. 7, P < 0.0001) ( Figure 2C ) b ut did 214 not correlate with age across all pediatric participants (Figure 2D ). 215 216 Children with COVID -19 were most infectious within first five days of illness 217 To define the likely period of infectiousness in our pediatric population, we analyzed viral load, 218 culturability , and TCID50 in comparison with duration of symptoms. Of note, duration of 219 symptoms does not necessarily indicate duration of infection, as time infection was acquired 220 cannot be confirmed. Consistent with prior reports in adults [9] , viral load s in children w ere the 221 highest earliest in the course of illness and declined over time after symptom onset (Pearson, r 222 = -0.4, P <0.001) ( Figure 3A). Viral load was highest in the first two days of symptoms , with 223 significant decrease after 5 days of symptoms and further decline after 10 days of sympt oms (P 224 < 0.0001) ( Figure 3B). Analysis of pediatric viral culture results demonstrated that children 225 tested early after symptom onset were more likely to shed replication competent virus (P = 226 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 17, 2021. ; https://doi.org/10.1101/2021.05.30.21258086 doi: medRxiv preprint 0.004) ( Figure 3C). Correspondingly , semi -quantitative assessment of infectious vir al shed ding 227 in children showed that the TCID50 was higher early after symptom onset and decreased over 228 time . When grouped by days of symptoms, children in days 0 -2 of their symptoms had the 229 highest infectivity, while children with greater tha n six days of illness shed less virus (P = 0.00 4) 230 (Figure 3D). 231 232 We then sought to assess whether COVID -19 severity impacted the relationship between viral 233 load and age in pediatric cohorts of varying severity : asymptomatic, mildly symptomatic, and 234 moderate/severe pediatric COVID -19 patients. None of these COVID -19 seve rity groups 235 revealed any correlation of age with viral load (Figure 4A ). Further, there were no differences in 236 viral clearance over the duration of illness, not only when comparing mild pediatric COVID -19 237 with moderate/severe COVID -19, but also when compar ing pediatric COVID -19 with adults 238 hospitalized with COVID -19 (Figure 4B ). Duration of symptoms did not affect the finding that 239 viral load does not correlate with age of the infected child ( Supplemental Figure 2 ). 240 241 Pediatric SARS -CoV -2 sequences were representative of those found in the community 242 We successfully performed whole -viral sequencing of 57 respiratory samples from 54 children. 243 Phylogenetic analysis of these pediatric sequences with contemporaneous Massachusetts 244 sequences from GISAID showed that they were represent ative of the spectrum of sequences 245 found in the community ( Figure 5). Notable variants identified in the p ediatric samples included 246 four Alpha ( B.1.1.7 ) and three lota (B.1.526.2) variants. To validate our culture results on a 247 subset of culture -positive samples , we sequenced virus isolated from the supernatant from 8 248 positive samples. Sequences from the supernatant and respiratory specimens were identical in 249 7 cases and demonstrated only 1 nucleotide change in the last case. 250 251 Discussion 252 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 17, 2021. ; https://doi.org/10.1101/2021.05.30.21258086 doi: medRxiv preprint As the global COVID -19 pandemic took hold , infected older a dults suffer ed high rates of 253 hospitalization and death while infected children typically experienced pauci symptomatic or 254 asymptomatic infection. While it is now clear that children can become infected with and 255 transmit SARS -CoV -2, viral dynamics in children have been understudied , and a full 256 understanding of the dynamics of infection in children is needed to inform public health polic ies 257 specific to the pediatric population. Here, we show that pediatric patients of all ages, from 258 infancy to young adulthood, can carry a high SARS -CoV -2 viral load in their upper airways , 259 particularly early in the course of infection, and an elevated viral load correspond s with high 260 levels of viable , replicating virus. Pediatric sequences were largely reflective of those found in 261 the general community and the presence of novel variants was identified. 262 263 Our findings have significant implications for both public health policy and the potential role of 264 universal vaccination of pediatric populations in fully curbing the COVID -19 pandemic . As 265 vaccination has rolled out in adult populations, public health poli cies are being adjusted to 266 account for changes in risk that result from vaccination. Our results emphasize the importance 267 of considering and clarifying how these policy changes relate to children. As adult populations 268 have been vaccinated, pediatric cases have represented a growing proportion of infections, 269 currently accounting for up to 25% of all COVID -19 cases across different regions of the United 270 States [3] . Our results suggest that the low rates of transmission in settings such as schools an d 271 daycares cannot be attributed to low viral loads, low rates of viral shedding, or rapid clearance 272 of virus in younger patient populations. As changes in masking and distancing policies are 273 implemented for vaccinated adults, consideration of how and whether policies changes will be 274 applied for children will be critical for ongoing reduction of new COVID -19 cases. 275 276 Our results additionally suggest that pediatric populations have the potential to serve as a 277 community res ervoir of actively replicating virus , with implications for both new waves of 278 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 17, 2021. ; https://doi.org/10.1101/2021.05.30.21258086 doi: medRxiv preprint infection and the evolution of viral variants. The duration of natural and vaccine -induced 279 immunity for each vaccine in clinical use are not yet known. If a community reservoir of actively 280 replicating virus is maintained and transmitted within unvaccinated pediatric populations, that 281 population could then serve as a source of new infections as vaccine -induced immunity wanes 282 in vaccinated adult populations . In addition, viral genomic variants were readily identified in the 283 pediatric samples and t hese variants have the potential to impact viral transmission [23 -25] , 284 disease severity [26, 27] , and vaccine efficacy [28] . Ongoing viral replication within pediatric 285 populations has the potential to serve as a source of existing and new viral variants that 286 interfere with eradication efforts. 287 288 Our study has several limitations. First, the data collected here represent a single medical 289 center and affiliated pediatric urgent care /COVID -19 screening clinic s. However, these were 290 amongst the few pediatric testing centers encompassing a large catchmen t area during the 291 duration of this study, and patients enrolled spanned a wide range of symptoms . Additionally, 292 many of these samples were collected early in the pandemic and SARS -CoV -2 variants of 293 interest have shifted over time . Ongoing studies analyzing shifts in virologic features of SARS - 294 CoV -2 infection in children alongside studies of infection in adults are needed to better 295 understand the full reach of the COVID -19 pandemic. 296 297 Ultimately , our data suggest that although age is generally protective a gainst severe disease, 298 children, especially early in the infection course, carry high viral loads of SARS -CoV -2, which 299 can include viral variants. Our results underline the importance of defining public health policy 300 with viral dynamics in children in mind and of including pediatric populations in vaccine efforts 301 aimed at eradication. 302 303 304 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 17, 2021. ; https://doi.org/10.1101/2021.05.30.21258086 doi: medRxiv preprint Acknowledgements : 305 The viral culture work was performed in the Ragon Institute BSL3 core, which is supported in 306 part by the NIH -funded Harvard University Center for AIDS Research (P30 AI060354). This 307 research was supported by the National Heart, Lung, and Blood Institute (5K08HL143183 to 308 LMY), the Department of Pediatrics at Massachusetts General Hospital for Children (to LMY) , 309 the Massachusetts Consortium for Pathogen Readiness and a gift from Mark and Lisa Schwartz 310 (to JZL) . 311 312 Conflicts of Interest 313 The authors do not report any conflicts of interest. 314 315 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 17, 2021. ; https://doi.org/10.1101/2021.05.30.21258086 doi: medRxiv preprint 316 1. Mehta NS, Mytton OT, Mullins EWS, et al. SARS -CoV -2 (COVID -19): What Do We Know About 317 Children? A Systematic Review. Clin Infect Dis 2020 ; 71:2469 -79. 318 2. Heald -Sargent T, Muller WJ, Zheng X, Rippe J, Patel AB, Kociolek LK. Age -Related Differences 319 in Nas opharyngeal Severe Acute Respiratory Syndrome Coronavirus 2 (SARS -CoV -2) Levels in 320 Patients With Mild to Moderate Coronavirus Disease 2019 (COVID -19). JAMA Pediatr 2020 ; 321 174:902 -3. 322 3. https://services.aap.org/en/pages/2019 -novel -coronavirus -covid -19 -infections/children -and - 323 covid -19 -state -leve l -data -report/ . 324 4. https://www.mass.gov/info -details/covid -19 -res po nse -reporting . 325 5. Yonker LM, Neilan AM, Bartsch Y, et al. Pediatric Severe Acute Respiratory Syndrome 326 Coronavirus 2 (SARS -CoV -2): Clinical Presentation, Infectivity, and Immune Responses. J Pediatr 327 2020 ; 227:45 -52 e5. 328 6. Fialkowski A, Gernez Y, Arya P, Weinacht K G, Kinane TB, Yonker LM. Insight into the pediatric 329 and adult dichotomy of COVID -19: Age -related differences in the immune response to SARS - 330 CoV -2 infection. Pediatr Pulmonol 2020 . 331 7. Soriano -Arandes A, Gatell A, Serrano P, et al. Household SARS -CoV -2 transmission and 332 children: a network prospective study. Clin Infect Dis 2021 . 333 8. L'Huillier AG, Torriani G, Pigny F, Kaiser L, Eckerle I. Culture -Competent SARS -CoV -2 in 334 N asopharynx of Sym ptomatic N eonates, Children, and Adolescents. Emerg Infect Dis 2020 ; 335 26:2494 -7. 336 9. Weiss A, Jellingso M, Sommer MOA. Spatial and temporal dynamics of SARS -CoV -2 in COVID - 337 19 patients: A systematic review and meta -analysis. EBioMedicine 2020 ; 58:102916. 338 10. Fajnzylber J, Regan J, Coxen K, et al. SARS -CoV -2 viral load is associated with increased 339 disease severity and mortality. N at Commun 2020 ; 11:5493. 340 11. Wolfel R, Corman VM, Guggemos W, et al. Virological assessment of hospitalized patients 341 with COVID -2019. Nature 2020 ; 581:465 -9. 342 12. https://www.cdc.gov/coronavirus/2019 -ncov/index.html . 343 13. Madhi SA, Baillie V, Cutland CL, et al. Efficacy of the ChAdOx1 nCoV -19 Covid -19 Vacc ine 344 against the B.1.351 Variant. N Engl J Med 2021 . 345 14. Liu Y, Liu J, Xia H, et al. BN T162b2 -Elicited N eutralization against N ew SARS -CoV -2 Spike 346 Variants. N Engl J Med 2021 . 347 15. Shinde V, Bhikha S, Hoosain Z, et al. Efficacy of N VX -CoV2373 Covid -19 Vaccin e against the 348 B.1.351 Variant. N Engl J Med 2021 . 349 16. Lima R, Gootkind EF, De la Flor D, et al. Establishment of a pediatric COVID -19 biorepository: 350 unique considerations and opportunities for studying the impact of the COVID -19 pandemic on 351 children. BMC M ed Res Methodol 2020 ; 20:228. 352 17. Harris PA, Taylor R, Thielke R, Payne J, Gonzalez N , Conde JG. Research electronic data 353 capture (REDCap) --a metadata -driven methodology and workflow process for providing 354 translational research informatics support. J Biome d Inform 2009 ; 42:377 -81. 355 18. Choi B, Choudhary MC, Regan J, et al. Persistence and Evolution of SARS -CoV -2 in an 356 Immunocompromised Host. N Engl J Med 2020 ; 383:2291 -3. 357 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 17, 2021. ; https://doi.org/10.1101/2021.05.30.21258086 doi: medRxiv preprint 19. Gonzalez -Reiche AS, Hernandez MM, Sullivan MJ, et al. Introductions and early sprea d of 358 SARS -CoV -2 in the New York City area. Science 2020 ; 369:297 -301. 359 20. Quick J. nCoV -2019 sequencing protocol v1. Available at: 360 https://www.protocols.io/view/ncov -2019 -sequencing -protocol -bbmuik6w . 361 21. Katoh K , Rozewicki J, Yamada KD. MAFFT online service: multiple sequence alignment, 362 interactive sequence choice and visualization. Brief Bioinform 2019 ; 20:1160 -6. 363 22. Trifinopoulos J, Nguyen LT, von Haeseler A, Minh BQ. W -IQ -TREE: a fast online phylogenetic 364 tool for maximum likelihood analysis. N ucleic Acids Res 2016 ; 44:W232 -5. 365 23. Zhou B, Thao TTN, Hoffmann D, et al. SARS -CoV -2 spike D614G change enhances replication 366 and transmission. N ature 2021 ; 592:122 -7. 367 24. Deng X, Garcia -Knight MA, Khalid MM, et al. Transmission, infectivity, and neutralization of 368 a spike L452R SARS -CoV -2 variant. Cell 2021 . 369 25. Davies N G, Abbott S, Barnard RC, et al. Estimated transmissibility and impact of SARS -CoV -2 370 lineage B.1.1.7 in England. Sc ienc e 2021 ; 372. 371 26. Davies N G, Jarvis CI, Group CC -W, et al. Increased mortality in community -tested cases of 372 SARS -CoV -2 lineage B.1.1.7. N ature 2021 ; 593:270 -4. 373 27. Funk T, Pharris A, Spiteri G, et al. Characteristics of SARS -CoV -2 variants of concern B.1.1.7, 374 B.1.351 or P.1: data from seven EU/EEA countries, weeks 38/2020 to 10/2021. Euro Surveill 375 2021 ; 26. 376 28. Garcia -Beltran WF, Lam EC, St Denis K , et al. Multip le SARS -CoV -2 variants escape 377 neutralization by vaccine -induced humoral immunity. Cell 2021 ; 184:2372 -83 e9. 378 379 380 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 17, 2021. ; https://doi.org/10.1101/2021.05.30.21258086 doi: medRxiv preprint Table 1 : Participant Demographics, past medical history , reason for presenting for SARS -CoV -2 381 RT -PCR testing, and disease severity of children with COVID -19 (n= 110 ). 382 383 384 385 COVID + ch ild re n (N =1 1 0) Ag e, a vera g e ( m ax, m in ) 10 (0, 21) Se x, n ( % ) Ma le 62 (56) Fe male 48 (44) Ra ce, n ( % ) Wh it e 36 (33) Bl ack 11 (10) As ia n 4 (4) Ot her 45 (41) Et hnic it y , n ( % ) Hi sp an ic 42 (38) Pa st M ed ic a l H is to ry , n ( % ) Ob esit y 28 (25) As th m a 11 (10) Other 39 (35) Re aso n f o r p re se n tin g f o r C O VID -1 9 t e stin g, n ( % ) As ym pto m atic , e xp osu re 30 (27) Sy mpto m atic , e xp osu re 72 (65) Sy mpto m atic , n o e xp osu re 8 (7) CO VID -1 9 S everit y , n ( % ) Ho sp it a liz e d 36 (33) Su pple m en ta l o xygen 18 (16) Ou tp atie n t 75 (68) . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 17, 2021. ; https://doi.org/10.1101/2021.05.30.21258086 doi: medRxiv preprint Figure 1 : COVID -19 disease severity and SARS -CoV -2 viral load across age groups. A. Age of 386 pediatric patients with SARS -CoV -2 infection, stratified by disease severity: asymptomatic 387 (n=2 7), mild disease, outpatient (n=4 8), moderate/severe COVID -19 , hospitalized (n=1 8). 388 Analyzed by ordinary one -way ANOVA. B. SARS -CoV -2 viral load was quantified across a 389 range of disease severit ies . Patients presenting with <10 days of symptoms were compared, 390 including asymptomatic pediatric outpatients (n=2 7), mildly symptomatic pediatric outpatients 391 (n= 44 ), moderate/severe pediatric hospitalized patients with oxygen requirement (n=1 8), and 392 moderate/severe adult hospitalized patients (n=2 9). Analyzed by ordinary one -way ANOVA. C. 393 Vira l lo a d f o r e ach s p e cim en ( n = 110 ) w as d ete rm in ed b y q PC R, p lo tte d a gain st p arti cip an t a ge 394 and analyzed by Pear son correl at ion. D. Vira l l o ad le ve ls re porte d b y s ch oo l a ge g ro up : 0 -4 395 year s ol d (yo) – in fa nt t h ro ugh pr e -school ( n= 32 ), 5 -10yo – el em ent ary school ( n=23) , 11 -16yo – 396 mi dd le s c h oo l ( n = 3 3), 1 7yo a nd o ve r – hi gh school and higher educat ion (n= 22 ). A na ly ze d b y 397 or dinar y one -wa y ANO VA. Dott e d li n es d epic t lim it o f d e te ctio n . * P <0.0 5, *** P <0.0 01, **** P < 398 0. 0001 , ns = not si gni ficant 399 400 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 17, 2021. ; https://doi.org/10.1101/2021.05.30.21258086 doi: medRxiv preprint Figure 2 : SARS -CoV -2 culture results across age groups and viral load. A-B. Samples with 401 observable CPE (culture +) (n= 31 ) or without observable CPE (culture -) (n= 95 ) plotted against 402 viral load ( A) and participant age ( B) and compared using t test. C-D. Semiquantitative viral titer 403 expressed as TCID50/mL for culture positive samples plotted against corresponding viral load 404 (C) or participant age ( D), Analyzed using Pearson correlation. Dotted line depict s limit of 405 detecti on. **** P < 0.0001 406 407 408 409 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 17, 2021. ; https://doi.org/10.1101/2021.05.30.21258086 doi: medRxiv preprint Figure 3 : Culture positivity and duration of symptoms. A. Viral load for each specimen was 410 determined by qPCR and plotted against the duration of symptoms (in days). Analysis by 411 Pearson correlation . B. Viral load reported by binned duration of symptoms . Ordinary one -way 412 ANOVA used for analysis. C. Duration o f symptoms for samples with observable CPE (culture 413 +, n=29 ) and without observable CPE (culture -, n=85 ). Analysis by t test. D. Semiquantitative 414 viral titer reported by binned duration of symptoms , analyzed by ordinary one -way ANOVA . 415 Dotted lines depict limit of detection. ** P < 0.01, * *** P < 0. 0001 416 417 418 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 17, 2021. ; https://doi.org/10.1101/2021.05.30.21258086 doi: medRxiv preprint Figure 4 : Correlation of viral load with age and duration of illness based on disease severity. 419 A. Correlation of viral load and age, stratified by asymptomatic (n=30) , mild outpatient (n=48) 420 and moderate/severe hospitalized (n=18) cohorts. B. Viral load of hospitalized adult (n=29), 421 hospitalized pediatric participants requiring respiratory support (n=18) and pediatric outpatients 422 with mild disease (n=48), plotted again st duration of symptoms . Dotted lines depict limit of 423 detection. 424 425 426 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 17, 2021. ; https://doi.org/10.1101/2021.05.30.21258086 doi: medRxiv preprint Figure 5. Phylogenetic analysis of pediatric and community SARS -CoV -2 sequences. Maximum 427 likelihood tree generated from pediatric sequen ces (red) and 183 contemporaneous 428 Massachusetts sequences from GISAID. 429 430 431 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 17, 2021. ; https://doi.org/10.1101/2021.05.30.21258086 doi: medRxiv preprint Supplemental Table 1 : Past medical history of children infected with SARS -CoV -2. 432 433 Past Medical History - Pediatric Patients Acute rec urr en t p an crea tit is AD HD Alopec ia As th m a Au tis m Cardi ac conducti on disorde r Chroni c ki dne y di se ase Coats Plus Syndrom e Crohn's di se ase Cysti c Fibrosi s Eczema Epi le psy G6PD Defic ien cy Gl uta ric a cid em ia , t yp e 1 Live r tr anspl ant Mi to ch o ndria l c o mp le x 1 d efic ie n cy Ob esit y Ob str u ctive sleep a p nea Pr em atu rit y Si ck le c e ll tra it Spe ech de la y Subg lotti c ste nosi s Trache obronchom alaci a 434 435 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 17, 2021. ; https://doi.org/10.1101/2021.05.30.21258086 doi: medRxiv preprint Supplemental Table 2 : Demographics, past medical history and disease severity of adults with 436 COVID -19 (n= 29 ) included in analysis of SARS -CoV -2 viral load. 437 438 439 440 COVID+ adults (n=2 9 ) Age, average (m ax , m i n ) 62 (26,93) Sex, number (%) Mal e 13 (45) Female 16 (55) Race, number (%) White 20 (69) Black 5 (17) Asi an 0 (0) Ot her 4 (14) Et h n i c i t y, n u m b er (%) Hispanic 4 (14) COVID-19 Severity Hospitalized, number (%) 21 (100) Respiratory support 22 (78) Out pat i ent , number (%) 0 (0) . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 17, 2021. ; https://doi.org/10.1101/2021.05.30.21258086 doi: medRxiv preprint Supplemental Figure 1: Viral load by sample collection location. Viral load of samples collected 441 from nasopharynx (n= 60 ), anterior nares (n=47) , or oropharynx (n=1 9) were compared and 442 analyzed by ordinar y one -wa y ANO VA. n s = non -si gni ficant . 443 444 445 446 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 17, 2021. ; https://doi.org/10.1101/2021.05.30.21258086 doi: medRxiv preprint Supplemental Figure 2 : Viral load plotted against pediatric patient age, for patients with 0 -2 447 days symptoms (n= 67 ), 3 -5 days symptoms (n= 30 ), and >6 days of symptoms (n=2 9). No 448 signi ficant cor rel at ion in any groupi ng, w hen analyzed by Pear son correl at ion. Do tt e d li n es 449 depi ct lim it of det ection. ns = not si gni ficant . 450 451 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 17, 2021. ; https://doi.org/10.1101/2021.05.30.21258086 doi: medRxiv preprint

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