Component 2: Interpretation and Response

Once the results of the wastewater and surface testing are available, school/childcare leadership must then decide quickly what actions are warranted by the information. Once actions are determined, they need to be explained to staff and families. 

How does it work?

Once the school or child care learns of a positive finding on a surface swab or wastewater,  decisions need to be made about (1) whether to schedule responsive testing and for which individuals; (2) whether to immediately quarantine a room with one or more positive surface swabs; (3) whether to activate intensified COVID safety practices; and (4) how and when to communicate about the findings. To facilitate the decision making, sites using SASEA should have designated individuals for receiving the results and making decisions and a dashboard for tracking results over time.

Decision-making team

Environmental findings are not the same as positive diagnostic test. They are not person-specific, and there are currently no official county, state, or federal guidelines to guide a school or child care center’s decision-making in response to a surface or wastewater positive. Ideally sites using the SASEA system should have at least two people involved in these decisions – the principal or site director and a COVID lead. At our partner school sites in San Diego we have developed risk index that considers:

  1. The viral load of the positive wastewater sample (i.e., how infectious the person may be)
  2. The viral load of the positive surface samples 
  3. If there was a known positive case on campus in the previous 5 days or previous 6-10 days
  4. The background rate of viral spread in the school’s zipcode 
  5. The percentage of students and staff who have consented to and regularly participate in individual diagnostic testing:

The more risk indicators are present, the more additional layers of protection schools should consider enacting before response testing is deployed, and while waiting for results.

SASEA results dashboard

Each day’s results should be considered in the context of results from the past week or so, since repeated findings suggest greater urgency and wider testing. A results dashboard can be created and maintained in one of two of ways:

  1. Create a dashboard that automatically updates itself as soon as new results are uploaded. This can be done using Tableau, ArcGis, or open source options such as AirTable. Tableau model can be viewed here.
  2. Manually enter daily environmental signal results sent from the lab onto an Excel Sheet or google sheet. Tracking template coming soon.

Whether to schedule responsive testing

Environmental findings must be considered in the context of degree of community spread in the immediate neighborhood, environmental findings on the same day or the few days prior, and any diagnostic positives in the school/child care. Some SASEA sites think of environmental findings as blinking red lights – the more lights, the more vigorous the response. Others lean toward responding to each environmental finding vigorously. In all cases, judgment must be applied. We recommend immediately scheduling COVID testing for the classroom(s) with positive surface swabs and/or for the entire school in the case of positive wastewater without a concurrent positive surface swab.

Whether to quarantine a room with one or more positive surface swabs

If consent rates for a classroom with a positive surface swab are not high, the decision-making team may decide it’s prudent to quarantine the room on the basis of the surface swab finding since response testing would be unlikely to identify the source of the COVID. While this step is available, it is obviously better for both the infected person and the school community as a whole to identify specific cases if possible.

Activating intensified COVID safety practices

When a potential infection has been identified via environmental monitoring, sites should ensure extra precautions are taken until the positive person is diagnosed and isolated. This could include ensuring high levels of ventilation via HEPA filters, opening doors and windows, and engaging in double masking and/or utilizing higher quality and better fitting face masks such as N95s or certified KN95s. Schools may also choose to use outdoor teaching facilities at this time, if this is a viable option.  

How and when to communicate findings to school community

Each site will need to decide on the best methods to routinely communicate environmental results to the school community. Full transparency and rapid communication are vital to ensure ongoing cooperation, increase diagnostic testing uptake, and keep staff, children, and families feeling safer at school. We recommend that schools provide a minimum of weekly updates of environmental monitor findings. We also recommend sending notifications immediately when environmental signaling suggests there may be a potential case on campus via email, physical letter, or other methods that are commonly used and acceptable at that school site. Health communication materials should be sent alongside notification, to help  families navigate uncertainty and risks (see Component 5: Health Communication).


  • Time to receive, consider and take action on findings
  • Communication channels to staff and families
  • Trust among staff and families that leadership is taking actions to keep them safe
  • Staff with the skillset and time to manage environmental findings dashboard


  • Communication with families can be challenging, COVID is complex, and environmental screening is novel. Templates for phone conversations, email and signage are available in our resources section.


  • Time

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Next: Component 3A: Responsive Testing →