It's interesting. The group of colleagues infected at the same time as me (6 of us in total, third week in March), two have asthma. Their symptoms were less severe than the rest of us. All in our 50s, varying degrees of fitness and health.
Also, I was worried about Mr HKP due to his asthma. As he didnt get infected from me, and as my stranger symptoms developed he recognised them in a "flu" he had earlier in March, we now think he most likely had the virus before me. I said before, he commutes to London by train so was high risk to exposure. He was not as ill as I was either.
So based on my experience, I would agree with this.
However - in the UK we still await antibody tests so I should say we cant be 100% clinically certain that we had it (would eat my hat tho, textbook symptoms all round).
I still make sure Mr HKP uses his daily puffer and keeps stocked up