The most beneficial treatment for CVID is to replace or provide protective antibodies. These protective antibodies are called immunoglobulins. The main protective immunoglobulin is called IgG or immunoglobulin G. Although there are other immunoglobulins that are also protective, such as IgA and IgM, the replaced immunoglobulin is almost exclusively IgG. Replacement of protective antibodies is the mainstay of treatment that reduces the number and severity of infections and often reduces the course of the infection. It is not conclusively known if replacement of protective antibodies reduces the other health effects seen in CVID.

Protective antibodies or immunoglobulin are replaced as an infusion either intravenously or subcutaneously. These protective antibodies are collected from many healthy donors and undergo an extensive process before available to be used in people with CVID to ensure its safety.

Even though these protective antibodies are generally the same, different processing lends to different brands available for infusion. A person with CVID may try different brands of immunoglobulin if they are experiencing side effects or feel ill with immunoglobulin infusions. In some cases the specialist will prefer one brand over another depending on other health conditions and should be discussed thoroughly. Many people with CVID tolerate infusions very well and choose whether they prefer intravenous infusions in a hospital, at their home with a qualified nurse or perform subcutaneous infusion at home on their own.

Having so many choices allows the person with CVID to adjust treatment to their lifestyle and particular needs.