Burden of SARS-CoV-2 and protection from symptomatic second infection in children
Authors: Kubale John , Balmaseda Angel , Frutos Aaron M , Sanchez Nery , Plazaola Miguel , Ojeda Sergio , Saborio Saira , Lopez Roger , Barilla Carlos , Vasquez Gerald , Moreira Hanny , Gajewski Anna , Campredon Lora , Maier Hannah , Chowdhury Mahboob , Cerpas Cristhiam , Harris Eva , Kuan Guillermina , Gordon Aubree 
Published: January 2022

AbstractImportanceThe impact of the SARS-CoV-2 pandemic on children remains unclear. Better understanding of the burden of COVID-19 among children and their protection against re-infection is crucial as they will be among the last groups vaccinated.ObjectiveTo characterize the burden of COVID-19 and assess how protection from symptomatic re-infection among children may vary by age.DesignA prospective, community-based pediatric cohort study conducted from March 1, 2020 through October 15, 2021.SettingThe Nicaraguan Pediatric Influenza Cohort is a community-based cohort in District 2 of Managua, Nicaragua.ParticipantsA total of 1964 children aged 0-14 years participated in the cohort. Non-immunocompromised children were enrolled by random selection from a previous pediatric influenza cohort. Additional newborn infants aged ≤4 weeks were randomly selected and enrolled monthly, via home visits.ExposuresPrior COVID-19 infection as confirmed by positive anti SARS-CoV-2 antibodies (receptor binding domain [RBD] and spike protein) or real time RT-PCR confirmed COVID-19 infection ≥60 days prior to current COVID-19.Main Outcomes and MeasuresSymptomatic COVID-19 cases confirmed by real time RT-PCR and hospitalization within 28 days of symptom onset of confirmed COVID-19 case.ResultsOverall, 49.8% of children tested were seropositive over the course of the study. There were also 207 PCR-confirmed COVID-19 cases, 12 (6.4%) of which were severe enough to require hospitalization. Incidence of COVID-19 was highest among children aged <2 years—16.1 per 100 person-years (95% Confidence Interval [CI]: 12.5, 20.5)—approximately three times that of children in any other age group assessed. Additionally, 41 (19.8%) symptomatic SARS-CoV-2 episodes were re-infections, with younger children slightly more protected against symptomatic reinfection. Among children aged 6-59 months, protection was 61% (Rate Ratio [RR]:0.39, 95% CI:0.2,0.8), while protection among children aged 5-9 and 10-14 years was 64% (RR:0.36,0.2,0.7), and 49% (RR:0.51,0.3-0.9), respectively.Conclusions and RelevanceIn this prospective community-based pediatric cohort rates of symptomatic and severe COVID-19 were highest among the youngest participants, with rates stabilizing around age 5. Reinfections represent a large proportion of PCR-positive cases, with children <10 years displaying greater protection from symptomatic reinfection. A vaccine for children <5 years is urgently needed.Key PointsQuestionWhat is the burden of COVID-19 among young children and how does protection from re-infection vary with age?FindingsIn this study of 1964 children aged 0-14 years children <5 years had the highest rates of symptomatic and severe COVID-19 while also displaying greater protection against re-infection compared to children ≥10 years.MeaningGiven their greater risk of infection and severe disease compared to older children, effective vaccines against COVID-19 are urgently needed for children under 5.