The impact of SARS-CoV-2 variants on the likelihood of children identified as sources of infection in the NIH workforce: a cohort study

Abstract Background: Children (<18 years old) were not initially considered significant sources of infection (SOIs) for SARS-CoV-2. Risk mitigation strategies were thus prioritized for adults, and vaccination was inaccessible for children until mid-2021. Emergence of novel variants led to significant increases in COVID-19 cases in both children and adults. Whether these emergence events and increased vulnerability of unvaccinated children had a synergistic effect resulting in increased caseloads in adults requires further exploration. Methods: A retrospective cohort study was conducted among 3,545 workers diagnosed with COVID-19. Case details were compiled during contact investigations. Variants of concern were identified following sequencing of biological samples collected through employer-based testing programs. Logistic regression was performed to compare the odds of having a child SOI based on the dominant variant in the workforce. Results: One-fourth (24.5%) of the cohort reported having a child in-residence; 11.2% identified a child as their SOI. In Alpha-dominant months, the odds of having a child SOI were 0.3, and the child SOI was likely older (5-17 years old). The odds of having a child SOI increased to 1.3 and 2.2 in Delta- and Omicron-dominant months, respectively. The odds of having younger child SOIs (<5 years old) were significantly higher in Omicron-dominant months. Conclusions: Children were highly likely to acquire the virus and posed a significant risk of transmission to their adult caretakers during Delta- and Omicron-dominant months. Without proper mitigation strategies in both the home and the workplace, child-associated transmission can threaten operations in the forms of staff shortages. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This work was supported in part by the Division of Intramural Research (DIR) of the NIAID/NIH ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Analysis was conducted using deidentified data that were collected for public health purposes and determined as exempted from IRB as assessed by both National Institutes of Health IRB and George Washington University IRB. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors