When children are young, it may feel like they are constantly ill. Infants and toddlers often have near-daily runny noses, and fevers and cold symptoms seem to come monthly. Infections of the ears (otitis media), lower respiratory tract (bronchiolitis), skin (cellulitis), and GI tract (diarrhea) are distressingly common. For most children, mild infections are a right of passage and begin to subside after the first few years of life.

For some, however, recurrent infections signal something much more serious. Primary immunodeficiencies include a group of disorders in which the body’s immune system does not function normally. In total, this group of disorders includes more than 240 related issues, because there are many different parts to a functioning immune system. If just one part of the immune system is not working properly, it can lead to a whole host of issues. The severity of illness depends on the type of dysfunction and varies from being a mild inconvenience to potentially fatal. Primary immunodeficiencies are often inherited. They are not contagious but are lifelong.

Diagnosis of a primary immunodeficiency is often delayed until an infant or child is quite ill. Multiple hospitalizations for recurrent infections like pneumonia or severe gastrointestinal infections leading to growth failure are often the first clues that something is amiss. Often a child is not growing well and having unusual infections. One severe, life-threatening primary immunodeficiency is SCID—severe combined immunodeficiency— and is now being screened for as part of the newborn screening programs in all 50 states, as well as in the District of Columbia and Puerto Rico. Early diagnosis is essential in babies born with SCID and means the difference between life and death.

Selective IgA deficiency is perhaps the most common primary immunodeficiency. According to the American Academy of Allergy Asthma & Immunology, selective IgA deficiency is more common than both cystic fibrosis and sickle cell anemia. Unlike SCID, the symptoms of selective IgA deficiency can be so mild that a person may never be formally diagnosed with the disease. While general pediatricians are comfortable doing some screening tests, doctors such as allergists and immunologists are often involved in the diagnosis of a primary immunodeficiency.

Reviewed by Dr. Sara Connolly, April 2019


  • Infants and children are expected to have many mild illnesses each year.
  • Children with a primary immunodeficiency often have recurrent, difficult-to-treat infections or unusual infections.
  • Poor growth or loss of weight especially alongside recurrent infections might signal a primary immunodeficiency.


  1. Immune Deficiency Foundation. IDF SCID Newborn Screening Campaign.
  2. Immune Deficiency Foundation. Newborn Screening.
  3. Immune Deficiency Foundation. About Primary Immunodeficiencies.
  4. American Academy of Allergy Asthma & Immunology. PIDD Quiz.
  5. American Academy of Allergy Asthma & Immunology. Primary Immunodeficiency Disease.


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