Screening plans for SARS-CoV-2 based on sampling and rotation: an example in the school setting

Abstract

Screening plans for prevention and containment of SARS-CoV-2 infection should take into account the epidemic context, the fact that undetected infected individuals may transmit the disease, and that the infection spreads through outbreaks, creating clusters in the population. In this paper, we compare the performance of six screening plans based on poorly sensitive individual tests, in detecting infection outbreaks at the level of single classes in a school context. The performance evaluation is done by simulating different epidemic dynamics within the class during the five weeks following the day of the first infection. The plans have different costs in terms of number of individual tests required for the screening and are based on recurrent evaluations on all students or subgroups of students in rotation. Especially in scenarios where the rate of contagion is high, at an equal cost, testing half of the class in rotation every week appears to be better in terms of sensitivity than testing all students every two weeks. Similarly, testing one-fourth of the students every week is comparable with testing all students every two weeks, despite the first one is a much cheaper strategy. In the presence of natural clusters in the population, testing subgroups of individuals belonging to the same cluster in rotation may have a better performance than testing all the individuals less frequently. The proposed simulations approach can be extended to evaluate more complex screening plans than those presented in the paper.

“Scuola Sicura”: a school screening program to prevent the spread of COVID-19 among students in Piedmont, Italy

“…Screening was offered in addition to other mitigation strategies against the spread of SARS-CoV-2 in schools. The organization of screening was based on simulations and designed to maximize efficiency and outcome 14 and to reduce the number of rhino-pharyngeal swab tests that each child could undergo. This is in line with recommendations by the U.S. Centers for Disease Control that school screening may be useful in containing spread of the virus when community transmission is high or moderate, when offered frequently, when the test results are obtained rapidly, and measures for response to identification of positive cases are clearly defined.…”

“…Each class was subdivided into four groups on the basis of participant students; one group each week underwent screening, yielding one test per student per month. 14 The minimum proportion of students per class required for the class to be enrolled was 25%. Missed screening appointments were not rescheduled.…”

“Scuola Sicura”: a school screening program to prevent the spread of COVID-19 among students in Piedmont, Italy

“…Screening was offered in addition to other mitigation strategies against the spread of COVID-19 in schools. The organization of screening was based on simulations and designed to maximize efficiency and outcome 14 and to reduce the number of rhino-pharyngeal swab tests that each child could undergo. This is in line with the recommendations by the U.S. Centers for Disease Control that school screening may be useful in containing spread of the virus when community transmission is high or moderate, when offered frequently, when the test results are obtained rapidly, and measures for response to identification of positive cases are clearly defined.…”

“…Screening was offered in addition to other mitigation strategies against the spread of COVID-19 in schools. The organization of screening was based on simulations and designed to maximize efficiency and outcome 14 frequently, when the test results are obtained rapidly, and measures for response to identification of positive cases are clearly defined. 15 Program adherence Although 70% of the schools in Piedmont participated in the program, student adherence, which was on a voluntary basis, was 19.5% of the total target population, lower than expected.…”

“…Within each of these, participants were subdivided into four groups; one group each week underwent screening, yielding one test per student per month. 14 Screening was managed independently by the twelve Local Health Units (LHU) in Piedmont in collaboration with the schools. The school principal's offices handled communication with the families, collected informed consent, and provided the lists of participating classes and students to the LHU.…”