No.
This madness needs to stop. Let's just hope this is=some obedient virtue-signal offer type thing you often see in Japanese culture. Japan is 80% vaccinated. And they currently are rocking it in terms of Covid-19.
If you are vulnerable to Covid-19, don't go near the marathon. Everyone else, carry on. I don't think we should be concerned about healthy vaccinated marathon runners running outdoors. If they want to do it, so be it.
https://www.washingtonpost.com/world/2021/12/22/japan-covid-omicron-falling-cases/