What are the consequences of my kid having cmv infections?

Probably none: 50-80% of the population has been infected with cmv, mostly during childhood. A few people develop a mono like illness, e.g., fever, sore throat; but most are asymptomatic. Unless your kid has immune deficiency or an inter-current serious illness there is no reason to worry. If an adult develops immune deficiency the long ago infection can become active and serious.

Depends: If they get it from mom (first time infection) during pregnancy they can have brain damage or become deaf. Most have it in childhood where it is often similar to any other "virus" they have and get over.