Many people have symptoms of a cold or the flu when they get the virus.
Others who have had the virus may never know it, because they had no symptoms. In more serious cases, CMV may result in a mild viral pneumonia. Almost everyone is susceptible to the virus, although males ages 18-26 seem to be the least likely to get it. And like other viruses, once you've had them, your body retains the antibodies. For example, the immune systems of premature babies are not yet fully developed.