The intent is noble. Here are the challenges to overcome in this:
1) Test error rate is roughly 30% in best case. Assuming a 1% positive rate in a sample size of 30,000, that yields 300 of which 90 go undetected. A multi-test approach can reduce this further but will still leave undetected cases on the table.
2) Points of infection for a big city marathon weekend are high. Using Boston as an example and using my personal experience from 2018 when I was there form Friday to Monday, these points include:
a) Trip to Boston (departure airport, flight, BOS)
b) Hotel
c) Restaurants where I dine.
d) BAA 5K
e) Expo
f) Church (blessing of the athletes service)
g) Bus ride
h) Village
i) Start line staging
j) Course
k) Finish area
l) Trip home (BOS, flight, arrival airport)
m) Any shop in Boston I frequent
n) Any ride on the T or Uber
o) Walking around the city
Even with testing at packet pickup and before, there are just so many opportunities to introduce infection in this case. Do we isolate the marathoners away from the general local population? I would be against that as part of what makes this so special IS the interaction with the local population who shower such love and respect on us who earned that spot.
I would move that if this level of testing is needed as well as huge levels of protection to make a big city marathon happen, the experience will be far less than what it was pre-COVID-19. Give that, it would be WORTH IT to hold off from Boston or any other big city marathon until there is no longer a need for extreme mitigation efforts to make it happen.
The idea is noble. I do appreciate this thoughtful effort as I would LOVE to run Boston this September! I just want to analyze this out to see if it would work, and there are numerous challenges to overcome.