Seroprevalence of anti-SARS-CoV-2 antibodies among children and their parents in Greece.

School closures were enforced as measures to restrain the COVID-19 pandemic, based on the assumption that young children may play a key role in SARS-CoV-2 spread. This study aims to determine the prevalence of SARS-CoV-2 IgG antibodies in children and corresponding parents, in order to improve surveillance and estimate the prevalence of asymptomatic or subclinical COVID-19 cases. A prospective multicenter study was conducted between March and June 2021 in Greece. Children admitted to the hospital or examined in outpatient clinics for reasons other than COVID-19 and their parents were tested for anti-Spike SARS-CoV-2 IgG in serum. A questionnaire about clinical and demographic data was completed. The study included 823 participants: 427 children and 396 corresponding parents. The overall seroprevalence was 16.4% in parents and 13.8% in children. Among families with ≥ 1 seropositive child or parent, the combination of a seropositive parent and a corresponding seronegative child was 29.6%, a seronegative parent and a corresponding seropositive child was 24.7%, and a seropositive child with a corresponding seropositive parent was 45.7%. Age, level of education, and school or work attendance were not significantly associated with increased seropositivity. On the contrary, ethnic minority of Roma, close contact with known COVID-19 case, previous symptoms consistent with COVID-19, and mass gatherings were risk factors for seropositivity. The spread of SARS-CoV-2 during a period of lockdown in Greece was low in children and comparable to adults most likely due to intrafamilial transmission. Accordingly, it is unlikely that children have boosted virus transmission. • In the earliest months of the pandemic, it was demonstrated that children had significantly lower seroprevalence rates than the older age groups, due to the fact that children had decreased exposure to the virus, because of early public health interventions, such as school and day care closure. • Later, further studies reported that children have similar incidence rate of SARS-CoV-2 infection compared to adults in households and community settings. • In this seroprevalence study, the spread of SARS-CoV-2 infection during a period of lockdown in Greece with the predominance of the Alpha-variant was particularly low in children and comparable to adults, most likely due to intrafamilial transmission. • These study findings will be useful for decisions regarding non-pharmaceutical interventions during the pandemic, and especially, to guide in designing and implementing appropriate containment measures for schools and social gatherings.

Dimopoulou D ，Kyritsi M ，Dadouli K ，Vergadi E ，Tsiligianni E ，Papadimitriou E ，Mavridi A ，Giannakopoulos S ，Tsiourvopoulou G ，Palyvou M ，Angeli E ，Brikos N ，Eleftheriou I ，Spoulou V ，Michos A ，Gkentzi D ，Siomou E ，Papaevangelou V ，Grivea I ，Syrogiannopoulos G ，Galanakis E ，Hadjichristodoulou C ，Tsolia M ... -  《-》

Prevalence of SARS-CoV-2 Infection in Children and Their Parents in Southwest Germany.

Tönshoff B ，Müller B ，Elling R ，Renk H ，Meissner P ，Hengel H ，Garbade SF ，Kieser M ，Jeltsch K ，Grulich-Henn J ，Euler J ，Stich M ，Chobanyan-Jürgens K ，Zernickel M ，Janda A ，Wölfle L ，Stamminger T ，Iftner T ，Ganzenmueller T ，Schmitt C ，Görne T ，Laketa V ，Olberg S ，Plaszczyca A ，Cortese M ，Bartenschlager R ，Pape C ，Remme R ，Huzly D ，Panning M ，Weigang S ，Giese S ，Ciminski K ，Ankerhold J ，Kochs G ，Schwemmle M ，Handgretinger R ，Niemeyer CM ，Engel C ，Kern WV ，Hoffmann GF ，Franz AR ，Henneke P ，Debatin KM ，Kräusslich HG ... -  《-》

SARS-CoV-2 seroprevalence among children in Greece during Omicron variant period.

The Omicron variant is associated with increased transmissibility, but evidence about the impact of Omicron in seropositivity of children is limited. This study aims to evaluate SARS-CoV-2 seroprevalence in children during the different variants' subperiods. A prospective multicenter seroprevalence study was conducted in 7 University public hospitals in Greece from November 2021 to August 2022 (3 subperiods: November 2021-February 2022, March 2022-May 2022, June 2022-August 2022). Children from different age groups, admitted to the hospital or examined in outpatient clinics for reasons other than COVID-19 were enrolled. Neutralizing antibodies (Nabs), anti-Spike (anti-S) and anti-nucleocapsid (anti-N) SARS-CoV-2 IgG in serum were evaluated. A total of 2127 children (males:57,2%; median age:4,8years) were enrolled. Anti-N IgG seropositivity increased from 17,8% in the first sub-period to 40,7% in the second sub-period and then decreased in the third sub-period (36,7%). Anti-S IgG seropositivity appeared to have an increasing trend over the study period, starting from 34,8% and reaching 80,7%. Children aged 1-4 years old have significantly higher anti-N IgG titers compared to children aged 0-1 years old (p < 0,001). Infants have significantly lower anti-S IgG titers compared to all other age groups (p < 0,001). Immunocompromised children and infants have the lowest seropositivity for NAbs.Conclusions During the Omicron period, seropositivity significantly increased, as a result of higher transmissibility. Neonates and infants have lower antibody titers compared to other age groups, while young children aged 1-4 years old present higher antibody titers, suggesting that this age group may mount a higher antibody response. Continuous surveillance seroprevalence studies are needed in children, in order to identify the true extent of SARS-CoV-2 and guide the planning of adequate public health measures.

Dimopoulou D ，Sotiri D ，Kousi D ，Loulou G ，Raptaki K ，Neofytou A ，Dasoula F ，Tampouratzi M ，Koloi A ，Eleftheriou E ，Vergadi E ，Papadimitriou E ，Zorbadaki I ，Mavridi A ，Miliordos K ，Steletou E ，Strempela M ，Fragkou PC ，Spoulou V ，Michos A ，Gkentzi D ，Papaevangelou V ，Ladomenou F ，Grivea I ，Syrogiannopoulos G ，Galanakis E ，Zaoutis T ，Tryfinopoulou K ，Tsolia MN ... -  《-》

Seroprevalence of SARS-CoV-2 Antibodies Among Children in School and Day Care in Montreal, Canada.

Zinszer K ，McKinnon B ，Bourque N ，Pierce L ，Saucier A ，Otis A ，Cheriet I ，Papenburg J ，Hamelin MÈ ，Charland K ，Carbonneau J ，Zahreddine M ，Savard A ，Fortin G ，Apostolatos A ，Haley N ，Ratté N ，Laurin I ，Nguyen CT ，Conrod P ，Boivin G ，De Serres G ，Quach C ... -  《JAMA Network Open》

Pre-Vaccine Positivity of SARS-CoV-2 Antibodies in Alberta, Canada during the First Two Waves of the COVID-19 Pandemic.

Charlton CL ，Nguyen LT ，Bailey A ，Fenton J ，Plitt SS ，Marohn C ，Lau C ，Hinshaw D ，Lutsiak C ，Simmonds K ，Kanji JN ，Zelyas N ，Lee N ，Mengel M ，Tipples G ... -  《Microbiology Spectrum》