Feasibility of SARS-CoV-2 Surveillance Testing Among Children and Childcare Workers at German Day Care Centers: A Nonrandomized Controlled Trial

Abstract

Importance: Closure of day care centers has been implemented globally to contain the COVID-19 pandemic but has negative effects on children's health and psychosocial well-being.

Objective: To investigate the feasibility of surveillance among children and childcare workers and to model the efficacy of surveillance on viral spread prevention.

Design, setting, and participants: This nonrandomized controlled trial was conducted at 9 day care centers in Wuerzburg, Germany, from October 2020 to March 2021. Participants included children attending day care, childcare workers, and household members. Participating day care centers were assigned to different surveillance modules in a nonrandomized feasibility study. A mathematical model for SARS-CoV-2 spread in day care centers was developed to identify optimal surveillance.

Interventions: Modules 1, 2, and 3 involved continuous surveillance of asymptomatic children and childcare workers by SARS-CoV-2 polymerase chain reaction testing of either midturbinate nasal swabs twice weekly (module 1) or once weekly (module 2) or self-sampled saliva samples twice weekly (module 3). Module 4 involved symptom-based, on-demand testing of children, childcare workers, and their household members by oropharyngeal swabs. All participants underwent SARS-CoV-2 antibody status testing before and after the sampling period. Questionnaires on attitudes and perception of the pandemic were administered in weeks 1, 6, and 12. Mathematical modeling was used to estimate SARS-CoV-2 spread in day care centers.

Main outcomes and measures: The primary outcomes were acceptance of the respective surveillance protocols (feasibility study) and the estimated number of secondary infections (mathematical modeling).

Results: Of 954 eligible individuals (772 children and 182 childcare workers), 592 (62%), including 442 children (median [IQR] age, 3 [2-4] years; 214 [48.6%] female) and 150 childcare workers (median [IQR] age, 29 [25-44] years; 129 [90.8%] female) participated in the surveillance. In total, 4755 tests for SARS-CoV-2 detected 2 infections (1 childcare worker and 1 adult household member). Acceptance for continuous surveillance was highest for biweekly saliva testing (150 of 221 eligible individuals [67.9%; 95% CI, 61.5%-73.7%]) compared with biweekly (51 of 117 individuals [43.6%; 95% CI, 35.0%-52.6%]) and weekly (44 of 128 individuals [34.4%; 95% CI, 26.7%-43.0%]) midturbinate swabbing (P < .001). Dropout rates were higher for midturbinate swabbing (biweekly, 11 of 62 participants [18%]; once weekly, 11 of 55 participants [20%]) than for saliva testing (6 of 156 participants [4%]). Mathematical modeling based on study and literature data identified biweekly testing of at least 50% of children and childcare workers as minimal requirements to limit secondary infections.

Conclusions and relevance: In this nonrandomized controlled trial, surveillance for SARS-CoV-2 in 9 German day care centers was feasible and well accepted. Mathematical modeling estimated that testing can minimize the spread of SARS-CoV-2 in day care centers. These findings enable setup of surveillance programs to maintain institutional childcare.

Trial registration: German Registry for Clinical Trials Identifier: DRKS00023721.

Figure 1.. Overview of Study Design

Children and childcare workers (CCWs) from day care centers (DCCs) were allocated (per DCC) to 1 of 4 surveillance modules, with respiratory sampling (laboratory analysis by polymerase chain reaction) planned for a period of 12 weeks. Blood sampling (finger prick test) for seroprevalence was conducted before and after the sampling period. Respiratory sampling was accompanied by psychosocial questionnaires at weeks 1, 6, and 12, and qualitative interviews were performed for a representative subsample of participants. As an additional service outside the regular testing schedule, on-demand testing was offered also for symptomatic DCC children and CCWs from modules 1, 2, and 3.

Figure 2.. General Overview of the Pandemic Activity in Wuerzburg During the Study Period

A, Top panel shows 7-day incidence per week for Germany, and bottom panel shows data for the city of Wuerzburg. B, Graphs shows rate of attendance of children in participating day care centers (DCCs) during the observation period. Data are the average attendance rate on Wednesdays of at least 8 of 9 DCCs.

Figure 3.. Day Care Center (DCC) Infection Spread Model

A, Structure of the virtual DCC. Arrows indicate interactions between different groups. B, State-based model with states depicted in boxes and state transitions as arrows that are defined by their corresponding transition rates. C, Distribution of number of secondary cases after introduction of an index case for each scenario 1 and scenario 3. CCW indicates childcare worker. Transition rates i, p, s, and τ are labeled with subscripts: im, infected-to-immune; inter, intergroup infection; intra, intragroup infection; iq, infected-to-quarantined/isolated; qi, quarantined-to-infected; qs, quarantined-to-susceptible; si, susceptible-to-infected; sq, susceptible-to-quarantine.