Unfortunately, whatever decrease there may be in terms of colds, flu, etc. will be far more offset by the enormous increase in mental health problems.
All ages will be effected. I see on these threads far too may people showing increasing signs of OCD type behavior, washing hands every half an hour or so - over-use of disinfectant and bleach in their homes.
Far too many people will think that other human beings are dangerous to them and refuse to come to close to anyone when out.
Every cough and sneeze will be treated as if that person has leprosy - (unclean, unclean).
Many people will develop symptoms that mean that they will be scared to leave (what they think of) as the safety of their homes.
And, it could leave us more vulnerable to things like colds, etc. One of the main reasons why older people seem to catch these less than younger ones is that they have built up an immunity over the years. We need to have that natural immunity in our systems.