I suggest you have a read of this:
A strong immune system can protect you against sickness. Learn which vitamins will keep your immune system strong, and how to get more of those nutrients in your diet.
health.clevelandclinic.org
Over the last 40 years, I have read a lot about nutrition and supplements. One supplement which I recently found interesting is monolaurin. It is contained in human breast milk for protecting the new born baby from viral infections. It's found in coconut milk and also available as a supplement. IMO, there's no risk in trying it. There is some info on the web on it and Amazon sells it.
That is my 2 cents.
I wish a prompt recovery to your wife. Have a good day!