My SIL and her family had it in July. Vitamin C, Vitamin D3 (you'll also want magnesium gluconate to get that to absorb well). She recommended a HOT epsom salt bath every day the first week HOT as you can stand. Apparently the hotter you can keep your body (beyond a fever, I wouldn't get in a hot bath if you're dealing with fevers) the less lung issues people in her church dealt with.
My BIL got it from his sister and all he had was a headache and lack of appetite and scratchy throat for 10 days.
My Brother and his family (family of 6) also had it in July it was out of their house with in 2 weeks and they didn't do anything special.
If we were to get it we'd start 1) vitamins 2) bone broth 3) elderberry syrup (but only the first few days) 4) rest rest rest and fluids.