Common variable immune deficiency (CVID) is the name for a group of
conditions that affect how the body’s immune system makes antibodies and
fights infections.

If you have CVID you are unable to make protective antibodies and therefore
become susceptible to infections. Both males and females can be affected by
CVID. The clinical features of CVID can vary from mild in those who suffer only
from infections to severe in those with disease-related complications.

Antibodies belong to a particular type of protein called immunoglobulin, which
is normally found in blood and body fluids. There are three major types of
immunoglobulin, known as:

  • Immunoglobulin G (IgG) – the most abundant and common immunoglobulin, found in blood and tissue fluids. IgG functions mainly against bacteria and some viruses.
  • Immunoglobulin A (IgA) – found in blood, tears and saliva. IgA protects the tissues of the respiratory, reproductive, urinary and digestive systems.
  • Immunoglobulin M (IgM) – found in the blood, IgM functions in much the same way as IgG but is formed earlier in the immune response.

All types are made up of antibodies against the germs that an individual has met
during the course of his or her life.

People with CVID have either low levels of immunoglobulin in their blood or none
at all; they are unable to make functional antibodies of the IgG or IgA types,
though some patients do make IgM antibodies. This means those affected can’t
fight infection against mainly bacteria, but also viruses, parasites and fungi, as
well as people with a fully working immune system. Patients may have severe,
persistent or repeated infections, often from the same germ. These infections
often particularly affect the ears, sinuses, chest, lungs or gut – places that come
into daily contact with infectious agents.

CVID covers a range of different deficiencies. The disorder is called ‘variable’
because of the extent and type of immune deficiencies. Furthermore, the clinical
course varies from patient to patient. In some patients, there is a decrease in
both IgG and IgA in the blood; in others, levels of all three major immunoglobulin types, IgG, IgA and IgM, may be decreased.

Since CVID patients are susceptible to bacterial infections due to missing
antibodies, the aim of treatment is to replace those antibodies with purified
immunoglobulins from the blood of healthy donors. Immunoglobulin therapy,
combined with antibiotics for breakthrough infections, means that people with
CVID can live relatively normal lives with no restrictions on employment. Many
patients with CVID work in healthcare or on farms.

The immunoglobulin therapy aims to prevent both infections and the
development of chronic lung disease. The outlook for patients with CVID
depends on how much damage has occurred to their lungs or other organs
before diagnosis and how successfully infections can be prevented in the future
by immunoglobulin therapy.

This page was reviewed by the Medical Advisory Panel April 2013. Revised July 2015.