Simulated identification of silent COVID-19 infections among children and estimated future infection rates with vaccination

Abstract

ImportanceA significant proportion of COVID-19 transmission occurs silently during the pre-symptomatic and asymptomatic stages of infection. Children, while being important drivers of silent transmission, are not included in COVID-19 vaccination campaigns given their exclusion from clinical trials thus far.ObjectiveTo investigate the impact of a targeted approach to identifying silent infections among children as a proxy for their vaccination.DesignThis study used an age-structured disease transmission model to simulate the synergistic impact of interventions in reducing attack rates over the course of one year.SettingA synthetic population representative of the demographics of the United States (US).ParticipantsSix age groups of 0-4, 5-10, 11-18, 19-49, 50-64, 65+ years old, stratified for their population size based on US census data.ExposuresVaccination of adults, self-isolation of all symptomatic cases within 24 hours of symptom onset, and detection of silent infections.Main Outcomes and MeasuresVaccination of adults was implemented to reach a 40% coverage over the course of one year with a vaccine efficacy of 95% against symptomatic and severe COVID-19. Without vaccination of children, we determined the proportion and speed that would be required for identifying silent infections among this age group to suppress future attack rates below 5%.ResultsA targeted approach that identifies 20.6% and 28.6% of silent infections among children within 2 or 3 days post-infection, respectively, would be required to bring attack rates under 5% with vaccination of adults. If silent infections among children remained undetected, achieving the same attack rates would require an unrealistically high vaccination coverage (at least 82%) of this age group, in addition to the base-case 40% vaccination coverage of adults. The results were robust in sensitivity analyses with respect to vaccine efficacy against infection and reduced susceptibility of children to infection.Conclusions and RelevanceIn the absence of vaccine availability for children, a targeted approach to rapid identification of silent COVID-19 infections in this age group can significantly mitigate disease burden. Without measures to interrupt transmission chains from silent infections, vaccination of adults is unlikely to contain the outbreaks in the near term.Key PointsQuestionWhat is the impact of a targeted strategy for identification of silent COVID-19 infections among children in the absence of their vaccination?FindingsIn this modelling study, we found that identifying 20-30% of silent infections among children within three days post-infection would bring attack rates below 5% if only adults were vaccinated. If silent infections among children remained undetected, achieving the same attack rate would require an unrealistically high vaccination coverage (at least 82%) of this age group, in addition to vaccination of adults.MeaningRapid identification of silent infections among children can replicate effects of their vaccination.

COVID-19 in Children: Where do we Stand?

“…The US CDC and other public health authorities recommend persons 12 years and older should get vaccinated with the Pfizer-BioNTech COVID-19 vaccine ( 87 ). An age-structured disease transmission model found that in a base-case scenario with an effective reproduction number R e = 1.2 and in the absence of vaccine availability for children, rapid identification of silent infections in this age group is required to mitigate disease burden ( 88 ). Vaccination of adults is unlikely to contain COVD-19 outbreaks soon without measures to interrupt transmission chains from silent infections ( 88 ).…”

“…An age-structured disease transmission model found that in a base-case scenario with an effective reproduction number R e = 1.2 and in the absence of vaccine availability for children, rapid identification of silent infections in this age group is required to mitigate disease burden ( 88 ). Vaccination of adults is unlikely to contain COVD-19 outbreaks soon without measures to interrupt transmission chains from silent infections ( 88 ). Vaccination of children and adolescents is recommended to protect them against COVID-19, but mostly to contribute to the achievement of herd immunity across all age groups ( 89 ).…”

Vaccinating Children Against COVID-19 is Essential Prior to the Removal of Non-Pharmaceutical Interventions

“…They describe this as a proxy for their vaccination, as vaccines were not available at the time for children. They found specific interventions for children were required in addition to adult vaccination to control disease outbreaks in the broader community [ 13 ]. While this study highlighted the need for targeted intervention strategies for children during the time when vaccines were unavailable, it did not explicitly consider their vaccination status.…”