Overall, children appear to be less frequently infected by, and significantly less affected by, SARS-CoV-2 virus and the clinical disease COVID-19. Large epidemiological studies have revealed children represent less than 2% of the total confirmed COVID-19 cases, of whom the majority experience minimal or mild disease that do not require hospitalisation. While everything is constantly changing, children also do not appear to be major drivers of SARS-CoV-2 transmission, with minimal secondary virus transmission demonstrated within families, schools and community settings.
Despite the claims by the media, compared to adults, children and/or adolescents tend to have a mild COVID-19 course with a good prognosis. In children the differences are highlighted by the lack of progression of the SARS-CoV-2 infection beyond mild symptoms in a majority of children, whereas in adults the disease progresses to acute lung injury and an acute respiratory distress syndrome (ARDS)- with high mortality.
To put this in perspective in a recent study (July 2021) of Twenty-three surveys representing 14 countries the median Infection fatality rate (IFR) of COVID-19 was for the various age categories
This shows that the young are at extremely low risk of Covid fatality. They reported the IFR was higher with larger proportions of people >85 years and that very low IFRs were confirmed in the youngest populations.a
To further put the low risk of Covid in infants and children in perspective with other risks a couple of graphs from the New York Times based on information from the Centre For Disease Control (CDC) in the US.
To put the risk of Covid in infants and children in perspective a couple of graphs from the New York Times based on information from the Centre For Disease Control (CDC) in the US.
In support of this the evidence suggests most laboratory confirmed cases of COVID-19 in children results in mild disease, with severe disease in children considered rare. 1 In a review of 65 articles that represented 1,214 children younger than five years showed nearly half of young COVID-19 cases were asymptomatic. 2 In another review of 19 eligible studies for a total of 2855 children and/or adolescents with COVID-19 Subjects presented mild symptoms in 79% of cases, whereas only 4% were critical. 3
There are now data from many geographic settings across Europe, Asia and America confirming that the proportion of children infected with SARS-CoV-2 in the community is low (varying from 1% in young children to 6% in older children). 4 To confirm this a modelling study demonstrated that susceptibility to SARS-CoV-2 infection in people under the age of 20 years is around half that of adults.5
China was the first country to experience intense community transmission, and a review of 72,314 cases by the Chinese Center for Disease Control (CDC) revealed that less than 1% of cases occurred in children aged less than 10 years, and the vast majority of these cases were well enough to be managed in the community.6 The United States (US) has subsequently emerged as the nation with the highest rates of infection and less than 2% of affected cases are in the paediatric age range. 7
Alongside a low prevalence of diagnosed disease, children also consistently exhibit mild (if any) illness following infection with SARS-CoV-2, including some traditionally ‘high risk’ children such as those with cancer, bone marrow transplant recipients, immunosuppressed children on biological agents, and those with cystic fibrosis. 8
While there are still limited data available regarding COVID-19 in infants, case reports regarding infants with SARS-CoV-2 infection have been favourable in the vast majority of infants with SARS-CoV-2 infection, including those presenting with less common and potentially more severe signs, including encephalopathy.9 In a review of 32 studies comprising 41 640 children and adolescents and 268 945 adults the evidence shows that children and adolescents have lower susceptibility to SARS-CoV-2 compared with adults.10 In another study they found that among children in educational-settings was lower than in communities. Evidence from school-based studies demonstrate it is largely safe for children (<10 years) to be at schools, however older children (10-19 years) might facilitate transmission. Despite this evidence, studies focusing on the effectiveness of mitigation measures in educational settings are urgently needed to support both public health and educational policy-making for school reopening. 11 In another review of 29 studies investigating information of symptoms and/or severity, it is evident that most children experience clinically mild disease or remain asymptomatically infected.12
Why are children less susceptible?
To put this in perspective children are generally more vulnerable to the flu than adults. But the opposite is the case for Covid. The leading hypotheses regarding their protection from acute illness and transmission relates to age-related differences in expression of angiotensin converting enzyme 2 (ACE2) and Transmembrane Serine Protease 2 (TMPRSS2) in the airway cells in children. These act like a trojan horse to carry the virus into the cells (Covid blog 2). The lower levels potentially limit viral entry and subsequent inflammation and injury. However, it may also be different immune responses compared to adults, as well as differences in angiotensin converting enzyme 2 (ACE2) distribution. 13,14,15,16.
Other factors also include comorbidities such as other chronic heath conditions and nutritional status, particularly vitamin D. Children generally have higher levels of vitamin D which is involved in modulating the immune system than adults. 17 Several studies have also demonstrated that higher levels of vitamin D are associated with better prognosis and outcomes in infectious diseases in older adults and that vitamin D might play a role in the prevention and/or treatment to SARS-CoV-2 infection disease, by modulating the immune response to the virus both in the adult and pediatric population.18 In one study of 25 children with COVID-19, they found that 72% of the patients were vitamin D deficient. Moreover, its level was significantly lower than the control group. 19 In another study of kids with a mean age of 10.7 years the mean serum vitamin D level was significantly lower in the COVID-19 group, 21.5 IU (International Units) compared to 28.0 IU in the control group. In addition, the proportion of patients with vitamin D deficiency was found in 44% in the COVID-19 group but only 17.5% in the control group. 20
Similar to adults, children with comorbidities (other health conditions) have been identified to be at significantly increased risk. In one study of 454 patients with a median age 11 years comorbidities including immunocompromise increased the risk by around 3.5 times, 2.7 times for gastrointestinal conditions 6.6 times for diabetes, and 2.2 times for asthma. 21
Unfortunately, obesity, hypertension, diabetes and metabolic syndrome which are the major risk factors for Covid have increased dramatically over the last 30 to 40 years. Paediatric hypertension for example in the United States, has increased fourfold. Currently up to 4.5 percent — or 3.34 million — of children in the United States have this condition. 22
Take out poor nutrition (Vitamin D) and commodities the risk for children is extremely low, and much lower than the annual influenza virus. However, there are still many things you can do to lower the risk even further for both children and adults such as increasing Vitamin D and supplementation with other nutrients which I will touch on in the next blogs
References
a. Infection fatality rate of COVID-19 in community-dwelling populations with emphasis on the elderly: An overview Cathrine Axfors. John P.A. Ioannidis doi: https://doi.org/10.1101/2021.07.08.21260210
1. Steinman J.B., Lum F.M., Ho P.P., Kaminski N., Steinman L. Reduced development of COVID-19 in children reveals molecular checkpoints gating pathogenesis illuminating potential therapeutics. Proc Natl Acad Sci U S A. 2020;117(40):24620–24626. [PMC free article].
2. Vaccine. 2021 Jan 22; 39(4): 667–677. Published online 2020 Dec 5. doi: 10.1016/j.vaccine.2020.11.078 PMCID: PMC7833125 PMID: 33342635 Epidemiology of COVID-19 infection in young children under five years: A systematic review and meta-analysis Mejbah Uddin Bhuiyan,a,1,⁎ Eunice Stiboy,b,1 Md. Zakiul Hassan,c Mei Chan,d Md. Saiful Islam,c,e Najmul Haider,f Adam Jaffe,d,g and Nusrat Homairad,g
3. Pediatr Res . 2021 Mar;89(4):733-737. doi: 10.1038/s41390-020-1015-2. Epub 2020 Jun 17. Coronavirus disease 2019 (COVID-19) in children and/or adolescents: a meta-analysis Alessandro Mantovani 1 , Elisabetta Rinaldi 2 , Chiara Zusi 2 3 , Giorgia Beatrice 2 , Marco Deganello Saccomani 4 , Andrea Dalbeni 5 PMID: 32555539 DOI: 10.1038/s41390-020-1015-2
4. Li X., Xu W., Dozier M. The role of children in transmission of SARS-CoV-2: a rapid review. J Glob Health. 2020;10 [PMC free article]
5. Davies N.G., Klepac P., Liu Y. Age-dependent effects in the transmission and control of COVID-19 epidemics. Nat Med. 2020;26:1205–1211. [PubMed]
6. Wu Z., McGoogan J.M. Characteristics of and important lessons from the coronavirus disease 2019 (COVID-19) outbreak in China: summary of a report of 72314 cases from the Chinese Center for Disease Control and Prevention. JAMA. 2020 ; Feb 24: (online ahead of print) [PubMed]
7. CDC COVID-19 Response Team Coronavirus disease 2019 in children – United States, February 12-April 2, 2020. MMWR Morb Mortal Wkly Rep. 2020;69:422–426. [PMC free article]
8. Pathology. 2020 Dec; 52(7): 801–808. Published online 2020 Aug 19. doi: 10.1016/j.pathol.2020.08.001 PMCID: PMC7437539 PMID: 32888706 SARS-CoV-2 in children: spectrum of disease, transmission and immunopathological underpinnings Phoebe C.M. Williams,1,2 Annaleise R. Howard-Jones,3 Peter Hsu,4,5 Pamela Palasanthiran,1,2 Paul E. Gray,1,2 Brendan J. McMullan,1,2 Philip N. Britton,3,5,6 and Adam W. Bartlett1,2,∗
9. Lorenz N., Treptow A., Schmidt S. Neonatal early-onset infection with SARS-CoV-2 in a newborn presenting with encephalitic symptoms. Pediatr Infect Dis J. 2020;39:e212. [PubMed]
10. JAMA Pediatr. 2021 Feb 1;175(2):143-156. doi: 10.1001/jamapediatrics.2020.4573. Susceptibility to SARS-CoV-2 Infection Among Children and Adolescents Compared With Adults: A Systematic Review and Meta-analysis Russell M Viner 1 , Oliver T Mytton 2 , Chris Bonell 3 , G J Melendez-Torres 4 , Joseph Ward 1 , Lee Hudson 1 , Claire Waddington 5 , James Thomas 6 , Simon Russell 1 , Fiona van der Klis 7 , Archana Koirala 8 , Shamez Ladhani 9 , Jasmina Panovska-Griffiths 10 , Nicholas G Davies 3 , Robert Booy 8 , Rosalind M Eggo 3 PMID: 32975552 PMCID: PMC7519436 DOI: 10.1001/jamapediatrics.2020.4573
11. J Glob Health. 2021 Jul 17;11:05013. doi: 10.7189/jogh.11.05013. eCollection 2021. Risk of infection and transmission of SARS-CoV-2 among children and adolescents in households, communities and educational settings: A systematic review and meta-analysis Omar Irfan 1 , Jiang Li 1 , Kun Tang 1 2 , Zhicheng Wang 2 , Zulfiqar A Bhutta 1 3 PMID: 34326997 PMCID: PMC8285769 DOI: 10.7189/jogh.11.05013
12. Sci Rep. 2021; 11: 13903. Published online 2021 Jul 6. doi: 10.1038/s41598-021-92500-9 PMCID: PMC8260804 PMID: 34230530 Children’s role in the COVID-19 pandemic: a systematic review of early surveillance data on susceptibility, severity, and transmissibility Katy A. M. Gaythorpe,#1 Sangeeta Bhatia,#1 Tara Mangal,#1 H. Juliette T. Unwin,#1 Natsuko Imai,#1 Gina Cuomo-Dannenburg,#1 Caroline E. Walters,#1 Elita Jauneikaite,#1 Helena Bayley,2 Mara D. Kont,1 Andria Mousa,1 Lilith K. Whittles,1 Steven Riley,1 and Neil M. Ferguson1
13. Pathology. 2020 Dec; 52(7): 801–808. Published online 2020 Aug 19. doi: 10.1016/j.pathol.2020.08.001 PMCID: PMC7437539 PMID: 32888706 SARS-CoV-2 in children: spectrum of disease, transmission and immunopathological underpinnings
14. Phoebe C.M. Williams,1,2 Annaleise R. Howard-Jones,3 Peter Hsu,4,5 Pamela Palasanthiran,1,2 Paul E. Gray,1,2 Brendan J. McMullan,1,2 Philip N. Britton,3,5,6 and Adam W. Bartlett1,2,∗
15. Am J Physiol Lung Cell Mol Physiol. 2020 Jul 1; 319(1): L39–L44. Published online 2020 Jun 3. doi: 10.1152/ajplung.00183.2020 PMCID: PMC7324935 PMID: 32491949. The Pathophysiology of COVID-19 and SARS-CoV-2 Infection Understanding the age divide in COVID-19: why are children overwhelmingly spared? K. Lingappan,1 H. Karmouty-Quintana,2 J. Davies,1 B. Akkanti,3 and M. T. Harting4
16. Allergy. 2020 Jun 4 : 10.1111/all.14429. doi: 10.1111/all.14429 [Epub ahead of print]
PMCID: PMC7300910 PMID: 32496587 Distribution of ACE2, CD147, CD26 and other SARS‐CoV‐2 associated molecules in tissues and immune cells in health and in asthma, COPD, obesity, hypertension, and COVID‐19 risk factors U. Radzikowska, 1 , 2 , 3 , † M. Ding, 1 , 2 , 4 , † G. Tan, 1 , 5 D. Zhakparov, 1 Y. Peng, 1 , 2 , 6 P. Wawrzyniak, 1 , 2 , 7 M. Wang, 1 , 2 , 8 S. Li, 1 , 9 H. Morita, 1 , 10 C. Altunbulakli, 1 , 2 M. Reiger, 11 AU. Neumann, 11 , 12 , 13 N. Lunjani, 1 , 2 C. Traidl‐Hoffmann, 2 , 11 K. Nadeau, 14 L. O’Mahony, 1 , 15 CA. Akdis, 1 , 2 and M. Sokolowska 1 ,
17. Am J Clin Nutr. 2019 Jul 1;110(1):150-157. doi: 10.1093/ajcn/nqz037. Vitamin D status in the United States, 2011-2014 Kirsten A Herrick 1 , Renee J Storandt 1 , Joseph Afful 2 , Christine M Pfeiffer 3 , Rosemary L Schleicher 3 , Jaime J Gahche 4 , Nancy Potischman 4 PMID: 31076739 PMCID: PMC7263437 DOI: 10.1093/ajcn/nqz037
18. J Endocrinol Invest. 2020 Jun 15 : 1–9. doi: 10.1007/s40618-020-01327-0 PMCID: PMC7299247 PMID: 32557271 Possible role of vitamin D in Covid-19 infection in pediatric population F. M. Panfili,#1 M. Roversi,#1 P. D’Argenio,2 P. Rossi,2 M. Cappa,3 and D. Fintini3
19. Darren Aet al.(2021) Vitamin D status of children with paediatric inflammatory multisystem syndrome temporally associated with severe acute respiratory syndrome coronavirus 2 (PIMS-TS). British Journal of Nutrition 12, 1–26. [PMC free article]
20. Epidemiol Infect. 2021; 149: e180. Published online 2021 Aug 10. doi: 10.1017/S0950268821001825 PMCID: PMC8365038 PMID: 34375576 Vitamin D levels in children with COVID-19: a report from Turkey Aysegul Alpcan, Serkan Tursun, and Yaşar Kandur
21. Pediatr Infect Dis J . 2021 Apr 1;40(4):e137-e145. doi: 10.1097/INF.0000000000003043. Risk Factors for Severe COVID-19 in Children Kelly Graff 1 , Christiana Smith 1 , Lori Silveira 1 , Sarah Jung 2 , Shane Curran-Hays 1 , Jane Jarjour 1 , Lauren Carpenter 3 , Kasey Pickard 3 , Michael Mattiucci 1 , JoEllen Fresia 3 , Elizabeth J McFarland 1 , Samuel R Dominguez 1 2 , Lisa Abuogi 1 PMID: 33538539 DOI: 10.1097/INF.0000000000003043
22. https://www.hopkinsmedicine.org/health/conditions-and-diseases/high-blood-pressure-hypertension/pediatric-hypertension
