Severity of SARS-CoV-2 Omicron BA.2 infection in unvaccinated hospitalized children: comparison to influenza and parainfluenza infections

References

• American Academy of Pediatrics. Children’s hospital association. Children and COVID-19: State Data Report. 2022.
   Google Scholar
• ChildStats.gov. Child population: Number of children (in millions) ages 0–17 in the United States by age, 1950–2020 and projected 2021-2050 2020 [cited 2022 6 April]. Available from: https://www.childstats.gov/americaschildren/tables/pop1.asp.
   Google Scholar
• Sinha IP, Harwood R, Semple MG, et al. COVID-19 infection in children. Lancet Respir Med. 2020;8(5):446–447.
   PubMed Web of Science ®Google Scholar
• US Centers for Disease Control and Prevention. Hospitalization of infants and children aged 0–4 years with laboratory-confirmed COVID-19 — COVID-NET, 14 States, March 2020–February 2022, https://www.cdc.gov/mmwr/volumes/71/wr/mm7111e2.htm. Morbidity and Mortality Weekly Report (MMWR). 2022.
   Google Scholar
• Tso WWY, Wong RS, Tung KTS, et al. Vulnerability and resilience in children during the COVID-19 pandemic. Eur Child Adolesc Psychiatry. 2022;31(1):161–176.
   PubMed Web of Science ®Google Scholar
• Flor LS, Friedman J, Spencer CN, et al. Quantifying the effects of the COVID-19 pandemic on gender equality on health, social, and economic indicators: a comprehensive review of data from march, 2020, to September, 2021. Lancet. 2022 Mar 2.
   PubMed Web of Science ®Google Scholar
• Crotty S. Hybrid immunity. Science. 2021;372(6549):1392–1393.
   Web of Science ®Google Scholar
• Walls AC, Sprouse KR, Bowen JE, et al. SARS-CoV-2 breakthrough infections elicit potent, broad, and durable neutralizing antibody responses. Cell. 2022;185(5):872–880.e3.
   PubMed Web of Science ®Google Scholar
• Abdullah F, Myers J, Basu D, et al. Decreased severity of disease during the first global omicron variant COVID-19 outbreak in a large hospital in tshwane, South Africa. Int J Infect Dis. 2022;116:38–42.
   PubMed Web of Science ®Google Scholar
• Brandal LT, MacDonald E, Veneti L, et al. Outbreak caused by the SARS-CoV-2 Omicron variant in Norway, November to December 2021. Euro Surveill. 2021;26(50.
   Google Scholar
• Christensen PA, Olsen RJ, Long SW, et al. Signals of significantly increased vaccine breakthrough, decreased hospitalization rates, and less severe disease in patients with coronavirus disease 2019 caused by the Omicron variant of severe acute respiratory syndrome coronavirus 2 in houston, texas. Am J Pathol. 2022;192(4):642–652.
   PubMed Web of Science ®Google Scholar
• Houhamdi L, Gautret P, Hoang VT, et al. Characteristics of the first 1119 SARS-CoV-2 Omicron variant cases, in marseille, France, November−December 2021. J Med Virol. 2022;94(5):2290–2295.
   PubMed Web of Science ®Google Scholar
• Wang L, Berger NA, Kaelber DC, et al. Comparison of outcomes from COVID infection in pediatric and adult patients before and after the emergence of omicron. medRxiv. 2022 Jan 2.
   Google Scholar
• Wang L, Berger NA, Kaelber DC, et al. COVID infection severity in children under 5 years old before and after Omicron emergence in the US. medRxiv. 2022 Jan 13.
   Google Scholar
• Cloete J, Kruger A, Masha M, et al. Paediatric hospitalisations due to COVID-19 during the first SARS-CoV-2 omicron (B.1.1.529) variant wave in South Africa: a multicentre observational study. Lancet Child Adolesc Health. 2022 Feb 18.
   PubMedGoogle Scholar
• Bhattacharyya RP, Hanage WP. Challenges in inferring intrinsic severity of the SARS-CoV-2 Omicron variant. N Engl J Med. 2022;386(7):e14.
   PubMed Web of Science ®Google Scholar
• Lavine JS, Bjornstad ON, Antia R. Immunological characteristics govern the transition of COVID-19 to endemicity. Science. 2021;371(6530):741–745.
   PubMed Web of Science ®Google Scholar
• Letter to Schools on “Arrangements on deferral of class resumption for all schools” (13 February 2020) [Internet]. 2020; 13 February [cited 10 May 2021]. https://www.edb.gov.hk/attachment/en/sch-admin/admin/about-sch/diseases-prevention/edb_20200213_eng.pdf.
   Google Scholar
• Arrangements of Early Commencement of Summer Holiday for All Schools [Internet]. (2020). 10 July [cited 10 May 2021]. https://www.edb.gov.hk/attachment/en/sch-admin/admin/about-sch/diseases-prevention/edb_20200505_eng.pdf.
   Google Scholar
• Continuation of Suspension of Face-to-Face Classes for Schools in Hong Kong: The Arrangements [Internet]. (2021). 4 January [cited 10 May 2021]. https://www.edb.gov.hk/attachment/en/sch-admin/admin/about-sch/diseases-prevention/edb_20210104_eng.pdf.
   Google Scholar
• Suspension of face-to-face classes of primary schools, kindergartens and kindergarten-cum-child care centres until Chinese New Year [Internet]. 2022; 11 January [cited 14 March 2022]. https://www.info.gov.hk/gia/general/202201/11/P2022011100677.htm.
   Google Scholar
• Letter to Kindergartens / Kindergarten-cum-Child Care Centres on “Arrangement of Special Vacation in the 2021/22 School Year” [Internet]. 2022; 28 February [cited 14 March 2022]. https://www.edb.gov.hk/attachment/en/sch-admin/admin/about-sch/diseases-prevention/edb_20220228_eng_d.pdf.
   Google Scholar
• HK Centre for Health Protection. Statistics. https://www.chp.gov.hk/en/static/24012.html#. 2022;2022.
   Google Scholar
• HK Centre for Health Protection. Detection of pathogens from respiratory specimens. https://www.chp.gov.hk/en/statistics/data/10/641/642/2274.html. 2022.
   Google Scholar
• HK Centre for Health Protection. COVID-19 Vaccination Programme. https://www.covidvaccine.gov.hk/en/dashboard. 2022;2022(12 February).
   Google Scholar
• Cheng VC, Ip JD, Chu AW, et al. Rapid spread of SARS-CoV-2 Omicron subvariant BA.2 in a single-source community outbreak. Clin Infect Dis. 2022 Mar 10.
   Web of Science ®Google Scholar
• Wang L, Berger NA, Kaelber DC, et al. COVID infection rates, clinical outcomes, and racial/ethnic and gender disparities before and after Omicron emerged in the US. medRxiv. 2022 Feb 22.
   Google Scholar
• Marks KJ, Whitaker M, Anglin O, et al. Hospitalizations of children and adolescents with laboratory-confirmed COVID-19 — COVID-NET, 14 states, July 2021–January 2022. MMWR Morb Mortal Wkly Rep. 2022;71(7):271–278.
   PubMed Web of Science ®Google Scholar
• Ludvigsson JF. Convulsions in children with COVID-19 during the Omicron wave. Acta Paediatr. 2022 Jan 31.
   Web of Science ®Google Scholar
• Tunc EM, Shin CKJ, Usoro E, et al. Croup during the COVID-19 Omicron variant surge. medRxiv. 2022: 2022.02.02.22270222.
   Google Scholar
• Brewster RCL, Parsons C, Laird-Gion J, et al. COVID-19-associated croup in children. Pediatrics. 2022 Mar 8.
   Google Scholar
• Murata Y, Tomari K, Matsuoka T. Children with croup and SARS-CoV-2 infection during the large outbreak of omicron. Pediatr Infect Dis J. 2022 Feb 17.
   Google Scholar
• Robinson ML, Morris CP, Betz J, et al. Impact of SARS-CoV-2 variants on inpatient clinical outcome. medRxiv. 2022 Feb 3.
   Google Scholar
• Sing CW, Woo YC, Lee ACH, et al. Validity of major osteoporotic fracture diagnosis codes in the clinical data analysis and reporting system in Hong Kong. Pharmacoepidemiol Drug Saf. 2017;26(8):973–976.
   PubMed Web of Science ®Google Scholar
• Chua GT, Wong JSC, Lam I, et al. Clinical characteristics and transmission of COVID-19 in children and youths during 3 waves of outbreaks in Hong Kong. JAMA Netw Open. 2021;4(5):e218824.
   PubMed Web of Science ®Google Scholar
• HK Centre for Health Protection. https://www.coronavirus.gov.hk. Hong Kong 2022.
   Google Scholar
• Sun JW, Bourgeois FT, Haneuse S, et al. Development and validation of a pediatric comorbidity index. Am J Epidemiol. 2021;190(5):918–927.
   PubMed Web of Science ®Google Scholar
• HK Centre for Health Protection. Seasonal Influenza. https://www.chp.gov.hk/en/features/14843.html. 2021.
   Google Scholar
• Fink EL, Robertson CL, Wainwright MS, et al. Prevalence and risk factors of neurologic manifestations in hospitalized children diagnosed with acute SARS-CoV-2 or MIS-C. Pediatr Neurol. 2022;128:33–44.
   PubMed Web of Science ®Google Scholar
• Ray STJ, Abdel-Mannan O, Sa M, et al. Neurological manifestations of SARS-CoV-2 infection in hospitalised children and adolescents in the UK: a prospective national cohort study. Lancet Child Adolesc Health. 2021;5(9):631–641.
   PubMedGoogle Scholar
• Hui KPY, Ho JCW, Cheung MC, et al. SARS-CoV-2 Omicron variant replication in human bronchus and lung ex vivo. Nature. 2022 Feb 1.
   PubMed Web of Science ®Google Scholar
• Nyberg T, Ferguson NM, Nash SG, et al. Comparative analysis of the risks of hospitalisation and death associated with SARS-CoV-2 omicron (B.1.1.529) and delta (B.1.617.2) variants in England: a cohort study. Lancet. 2022 Mar 16.
   Web of Science ®Google Scholar
• Ng KW, Faulkner N, Cornish GH, et al. Preexisting and de novo humoral immunity to SARS-CoV-2 in humans. Science. 2020;370(6522):1339–1343.
   PubMed Web of Science ®Google Scholar
• Kundu R, Narean JS, Wang L, et al. Cross-reactive memory T cells associate with protection against SARS-CoV-2 infection in COVID-19 contacts. Nat Commun. 2022;13(1):80.
   PubMed Web of Science ®Google Scholar
• Swadling L, Diniz MO, Schmidt NM, et al. Pre-existing polymerase-specific T cells expand in abortive seronegative SARS-CoV-2. Nature. 2022;601(7891):110–117.
   PubMed Web of Science ®Google Scholar
• HK Centre for Health Protection. CHP Newsletter, https://www.chp.gov.hk/files/pdf/chp50_en.pdf. 2022 (50).
   Google Scholar
• news.gov.hk. HK sees 25k COVID-19 cases (Chinese Version only) 2022 [updated 7 March 2022; cited 2022 6 April]. Available from: https://www.news.gov.hk/chi/2022/03/20220307/20220307_180507_220.html.
   Google Scholar
• HK Centre for Health Protection. Archives of latest situation of cases of COVID-19. https://www.chp.gov.hk/en/features/102997.html. 2022.
   Google Scholar
• Census and Statistics Department of the HKSAR. Hong Kong Annual Digest of Statistics (2021 Edition). Hong Kong2021.
   Google Scholar
• Chiu SS, Kwan MYW, Feng S, et al. Influenza vaccine effectiveness against influenza A(H3N2) hospitalizations in children in Hong Kong in a prolonged season, 2016/2017. J Infect Dis. 2018;217(9):1365–1371.
   PubMed Web of Science ®Google Scholar
• Chiu SS, Kwan MYW, Feng S, et al. Interim estimate of influenza vaccine effectiveness in hospitalised children, Hong Kong, 2017/18. Euro Surveill. 2018 Feb;23(8.
   PubMedGoogle Scholar
• Lau YL, Wong WHS, Hattangdi-Haridas SR, et al. Evaluating impact of school outreach vaccination programme in Hong Kong influenza season 2018 - 2019. Hum Vaccin Immunother. 2020;16(4):823–826.
   PubMed Web of Science ®Google Scholar
• Lauring AS, Tenforde MW, Chappell JD, et al. Clinical severity of, and effectiveness of mRNA vaccines against, COVID-19 from omicron, delta, and alpha SARS-CoV-2 variants in the United States: prospective observational study. Br Med J. 2022 Mar 9;376:e069761.
   PubMedGoogle Scholar
• Andrews N, Stowe J, Kirsebom F, et al. COVID-19 vaccine effectiveness against the Omicron (B.1.1.529) variant. N Engl J Med. 2022 Mar 2.
   Web of Science ®Google Scholar
• Walter EB, Talaat KR, Sabharwal C, et al. Evaluation of the BNT162b2 COVID-19 vaccine in children 5 to 11 years of Age. N Engl J Med. 2022;386(1):35–46.
   PubMed Web of Science ®Google Scholar
• Jara A, Undurraga EA, González C, et al. Effectiveness of an inactivated SARS-CoV-2 vaccine in Chile. N Engl J Med. 2021;385(10):875–884.
   PubMed Web of Science ®Google Scholar
• Lau Y-L, Duque JR, Wang X, et al. Immunogenicity and reactogenicity of SARS-CoV-2 mRNA and inactivated vaccines in healthy adolescents. Nat Commun. 2022: in press.
   Google Scholar
• UK Joint Committee on Vaccination and Immunisation (JCVI). JCVI statement on vaccination of children aged 5 to 11 years old. https://www.gov.uk/government/publications/jcvi-update-on-advice-for-covid-19-vaccination-of-children-aged-5-to-11/jcvi-statement-on-vaccination-of-children-aged-5-to-11-years-old. 2022.
   Google Scholar
• US Centers for Disease Control and Prevention. COVID-19 vaccines for children and teens. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/recommendations/children-teens.html?CDC_AA_refVal=https://www.cdc.gov/coronavirus/2019-ncov/vaccines/recommendations/adolescents.html. 2022.
   Google Scholar
• International League Against Epilepsy. COVID-19 vaccines and people with epilepsy. https://www.ilae.org/patient-care/covid-19-and-epilepsy/covid-19-vaccines-and-people-with-epilepsy. 2022.
   Google Scholar