SASEA Approach

The Safer at School Early Alert (SASEA) system was developed to provide daily, sustainable, anonymous, and school-wide COVID-19 monitoring for school and childcare sites using wastewater and surface samples rather than individual diagnostic tests.

Monitoring schools or childcare at the site and/or classroom level allows administrators and public health officials to deploy more resource and outreach intensive individual-level testing specifically when and where these are needed.

System goals

SASEA’s primary goal is to ensure that all students, staff, and their families feel safe at school, regardless of their neighborhood, race/ethnicity, or economic status. We have been developing and pilot-testing SASEA at 15 schools across San Diego County since November 2020. 

The Safer at School Early Alert system has four pillars:

  1. Mitigate the risk of in-person schooling by identifying cases before they become outbreaks
  2. Allow for the targeted deployment of PCR-diagnostic or antigen testing, including more intensive and tailored outreach to hesitant school communities.
  3. Alert schools to the need for more intensive risk mitigation measures (masking, ventilation) even in the absence of a known individual case through classroom-level environmental monitoring
  4. Provide long-term, ongoing monitoring for early identification of potential community outbreaks as vaccine uptake increases and community spread declines.

Evidence-based and validated

SASEA is an evidence-informed multi-pronged early alert system to detect asymptomatic COVID-19 cases before they become outbreaks in school and childcare settings.

The SASEA system was validated in communities that have borne the highest burden of COVID-19 related morbidity, mortality, and social-economic fallout and developed in partnership with 10 elementary schools and five childcare centers across the County of San Diego. Partner sites were chosen based on their equity score in the California Department of Public Health’s Healthy Places Index (HPI). Over the course of program development our team conducted 15 focus group discussions in Spanish and English and 5 key informant interviews, and fielded a bilingual (Spanish and English) survey with 300 staff and parents across participating sites to ensure that SASEA sufficiently considered the social, behavioral, cultural aspects of COVID-19 screening and testing.

SASEA System Components
SASEA System implementation components

SASEA consists of five implementation components

  1. Surface and Wastewater Monitoring
  2. Interpretation and Response
  3. Responsive Testing
  4. Diagnostic Positives: Quarantine/Isolation & Public Health Engagement
  5. Health Communications

These components are described briefly here, then elaborated in subsequent sections.

Component overviews 

1. Surface and Wastewater Monitoring

When a person is infected and shedding virus in their breath, pieces of the virus can escape their mask in the form of aerosols, which then settle on surfaces. These virus pieces can be detected by swabbing a small area of the floor each day before a classroom is cleaned.

Infected people also shed virus in their feces. Daily wastewater samples collected using an automated wastewater sampling robot can be analyzed for particles of the SARS-COV-2 virus (COVID-19).

Both the surface sample swabs and wastewater samples must be collected and transported to a lab for processing each day. Optimally, the samples are analyzed that evening/night or the next morning, and results are available within 24 hours of delivery to the lab.

Surface Sampling →

Wastewater Sampling →


2. Interpretation and Response

If either a wastewater or surface sample comes back positive, school or childcare leadership should consider that information along with the broader context when deciding on the next step. 

Responsive testing is typically necessary when there is a strong positive environmental sample (Cq value 35 or below). The campus community must be notified that responsive testing is imminent and that they need to redouble their commitment to COVID safety practices as responsive testing is deployed and while awaiting those results. 

Interpretation and Response →


3. Responsive Testing and Risk Mitigation

Responsive testing can be offered to either the full school community (in the case of a positive wastewater with no positive classroom surface swab), or to a specific classroom (in the case of a positive surface swab). The testing should be delivered at the school site during the school day. A critical requirement for responsive testing is to obtain consent to testing from as many members of the school community as possible.

Risk Mitigation →


4. Diagnostic Positives: Quarantine/Isolation & Public Health Engagement

Once a case has been identified, that person and any of their close contacts (sometimes deemed to be the whole stable classroom cohort) must be notified and supported to isolate (the case) or quarantine (contacts) safely. Public health authorities should be notified and can confer about contact tracing and quarantine/isolation questions. 

Diagnostic Positives: Quarantine/Isolation & Public Health Engagement →


5. Collaborate with Local Public Health Department

All positive test results should be reported to the local health department for case investigation and contact tracing efforts. 


← Back: Context for SASEA

Next: Component 1A: Surface Sampling →