I've just finished the walk about a week ago, and hope my experience/mistake can be of some help to future pilgrims. I spent a day or two in Madrid before and after walking the last 100 km to Santiago. The night before I started the walk, I realized that I was feeling sick (sore throat, cough, headache, general weakness, etc.). However, I simply pushed on and stayed in private rooms. It was a lot more challenging than I had anticipated because of the sickness, but I still was able to walk the last 100 km in 5 days (instead of 4 days I originally planned) and was feeling somewhat better by the time I arrived in Santiago. After coming back to Madrid from Santiago the next day, I took the airport express bus to the Madrid airport and flew back home. Within a day after coming back home, I became very sick and had to stay in the bed for 5-6 days.
In hindsight, it seems this is what happened. I contracted a mild/moderate form of cold virus in the crowded buses/ subway in Madrid before the walk, and after the walk while in Madrid I then again contracted some respiratory virus, this time a rather virulent one. I noticed that people in the bus/subway were coughing without covering their months and practically no one wore masks. This one lady in particular on the bus was coughing loud frequently while having a conversation with her friend during the entire ride to the airport.
If I had been aware of the high probability of getting sick from riding public transportation in Spain, I would definitely have worn a mask (not any masks, but the N-95 mask) and may have used either taxi or Uber instead. Almost nothing seems more important than not getting sick immediately prior to starting the walk.
In hindsight, it seems this is what happened. I contracted a mild/moderate form of cold virus in the crowded buses/ subway in Madrid before the walk, and after the walk while in Madrid I then again contracted some respiratory virus, this time a rather virulent one. I noticed that people in the bus/subway were coughing without covering their months and practically no one wore masks. This one lady in particular on the bus was coughing loud frequently while having a conversation with her friend during the entire ride to the airport.
If I had been aware of the high probability of getting sick from riding public transportation in Spain, I would definitely have worn a mask (not any masks, but the N-95 mask) and may have used either taxi or Uber instead. Almost nothing seems more important than not getting sick immediately prior to starting the walk.