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

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. What is already known on this topic Increases in transmission trends related to SARs-CoV-2 Variants of Concern have been documented in the literature at the population level and in workplaces. What this study adds This study looks more closely at the role that children played in transmission to adult workers, and therefore their potential to seed transmission outside of the home. This interface of transmission has been neglected in the literature but is key for future policy development. How this study might affect research, practice, or policy Transmission of SARS-CoV-2 from children to their caretakers may cause significantly increased odds of infection in a worker population. This may have second order effects for staffing, particularly in workgroups with employees of childbearing age. Employers should consider this in the design of their policies for continuity of operations, telework, and leave.