Kids Need to be in School. Here is one way to do it (safely).

President Trump was correct about one thing.  We need to send the kids back to school in the fall.

But it is unbelievably negligent for him to suggest doing so without a plan to contain the virus.



Let's look at the data:
  • According to the American Academy of Pediatrics, children represent 8.2% of all available Covid-19 cases in the state of Maryland (Reference)
There is little doubt about the contagiousness of these kids, especially in an indoor environment where aerosol transmission predominates.  

I did a quick statistical analysis:
  • On July 9, Maryland had 463 positive test cases (7-day moving average positivity rate was 5.2%) (reference). 
  • Using the above assumptions for case rate of children and Maryland's July 9 test numbers, a school containing 600 students will have a 79% chance of having at least one contagious student.  
  • If Maryland reaches the virus prevalence levels that we had back in April again, that same school will have a 93% chance of containing contagious student(s).  
  • If we reach where Florida is today in terms of virus prevalence, there is a 100% chance the school will have more than one contagious student.  
  • With Florida's numbers, an average classroom will have an 86% chance of having at least one student out of 30 with Covid-19.
It is clear that the virus prevalence will change throughout the school year and we will need a means of measuring and controlling the risk if we are going to send the kids to school.

Virtual Learning
Since there is a good chance that Covid-19 will be prevalent in our area during the next school year, an ideal scenario would be to have 100% of the students learn virtually, at home, and be totally safe.  But this is not possible or practical for many families, especially dual wage earners.  

And, it is probably not healthy for students to spend another school year in isolation, with no social experiences (yes I believe the virus will be with us for the entire school year).

In addition, many families lack the resources to have internet connectivity and electronic devices, which would preclude virtual learning experiences for these folks.

For these reasons, I'd recommend keeping mandatory virtual learning for only when the virus prevalence is high - say above 5%.

Learning Pods
There is a way to allow kids to go to school during moderate virus prevalence (say when the test positivity rates are between 1% and 5%), as long as the risk of infection can be isolated to a smaller number of students. 

Say there are 600 students in an elementary school.  Dividing up those kids into 10 pods (of 60 students each) and keeping them as isolated as possible would confine any infections to that pod.  See the tables below for an example of how that can be done.  





As you can see, the start times would need to be staggered.  Busses would be uniquely assigned to pods, which would be organized by neighborhood to simplify the bus routing.  And bathroom schedules (with cleaning in between usage of each pod of students) would need to be adhered to.

Cafeterias would have to be pick-up (brown bag) only.  Note that lunchtimes at school are especially risky times for potential virus transmission and eating in the classroom would partially mitigate this issue.  

All after school activities and gym classes would need to be cancelled.

Frequent testing of students should be mandatory.  Any positive test results in a pod would mean those 60 students would need to be at home for the next 14 days, learning virtually.  And then retested before going back into the school.

Enforcement of mask-wearing inside the school would be helpful in mitigating the virus transmission risk within a pod. (Although I'd imagine that it might be difficult to get a six year old to properly wear a mask for 7 hours a day.)

There is good evidence that other social distancing measures, implemented in schools, can be very effective at quelling transmission of the virus.  For example, operating a school with reduced capacity and increased distances between desks is recommended.  In addition, increased ventilation will be very important as well (reference).  

Of course, families with the means to do so might choose home schooling during this period which would provide the same protection as a virtual learning environment - and reduce the load for the pods system.  

Implementing the system
Ideally, this should be implemented at as local a level as possible.  The test positivity rates for the population should be measured at the county level, or at the school district level if large enough to have a good statistical basis.

Here is one implementation, using a red / yellow / green scheme:


If the Covid-19 test positivity rate in the county (or school district) exceeds 1%, then the pods system would be implemented (code yellow).  If the positivity rate exceeds (say) 5%, then all learning would go 100% virtual (code red).  Once the prevalence returns to below 1% (for some period of time) then the school system could return to business as usual.

All of these modes must be implemented with a rigorous, statistically verified testing regimen.  The turn around time for the tests must be rapid - say within 48 hours - for the system to work.

I would recommend the use of a 7 day moving average for the positivity rates (or perhaps a measurement with even more inertia) to avoid frequent stopping and restarting the pods system.

I will add that school districts are starting to figure this out.  Montgomery County (MD) just put out their plan which seems sensible to me (reference).  Missing from their plan, however, is a testing regimen with thresholds of when to return to virtual learning.  

This is going to be a tough year for all of us.  There is no doubt that schools could potentially represent one of the biggest sources of transmission for Covid-19 and it is essential that school districts adopt sensible measures to control and bound the risks.

The scheme presented here is only one of many potential ways to skin this cat.

Finally, here is a very well-researched article with data from around the world for those interested in learning more about the topic of opening schools in the fall (reference).

Acknowledgements
I am not at all experienced in teaching or dealing with school resources such as buses.  Hardiest thanks to Jessica Krasnick and Jerry Riecke for providing much needed professional assistance for this blog post.

The opinions expressed herein as well as any errors are solely mine.




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