What is primary immunodeficiency (PID)?

A PID is a disorder where the immune response is weakened or absent altogether. They are often genetic in origin i.e. inherited and result in a defect in one or more elements of the immune system. People with PID’s are prone to infections which may be frequent, more severe or last longer than in individuals who have a fully functioning immune system.

Diagnosis may occur at any stage of life with or without symptoms (increasing the risk of late or missed diagnosis). Some patients may not receive a diagnosis until reaching adulthood when they begin to present with clinical symptoms of a PID. Other PID’s are fatal without early diagnosis and treatment such as Severe Combined Immunodeficiency (SCID).

Depending on the type of PID some people manage their condition quite well with appropriate treatment while others live with lifelong chronic illness and complex medical issues.

The International Union of Immunological Societies (IUIS) Expert Committee has classified up to 430 inborn errors of immunity/primary immunodeficiencies in their 2019 update. While this may seem like a large number it’s important to recognise that individual PID’s are still considered a rare disease i.e. the number of affected people is 5 < 10,000.

What is secondary immunodeficiency (SID)?

SID’s occur when the immune system is weakened as a result of treatment for an illness (e.g. chemotherapy for treatment of cancer) or medications, or CAR T cell therapy.
Many of the treatment options and supports offered to PID patients are similar for SID patients.

Are immune deficiency and immunodeficiency the same?

Commonly used terms include immunodeficiency, immune deficiency, immunodeficiency disease or immune deficiency disorder.

What are the warning signs of a PID?

These warning signs are a guideline only. Many PID patients may experience the following signs and symptoms:

  1. Eight or more ear infections within one year
  2. Two or more serious sinus infections within one year
  3. Two or more months on antibiotics with little effect
  4. Two or more pneumonias within one year
  5. Failure of an infant to gain weight or grow normally
  6. Recurrent deep skin or organ abscesses
  7. Persistent thrush in mouth or elsewhere on skin after age one
  8. Need for intravenous antibiotics to clear infections
  9. Two or more deep seated infections such as sepsis, meningitis or cellulitis
  10. Family history of primary immunodeficiency
Are PID’s contagious?

No. PID’s are caused by defects in the genes controlling the immune system. People are born with PID’s; you cannot catch or become infected with a PID however they may be passed from a parent to a child depending on the type of condition. A genetic counsellor may assist with explaining this and the impact for you and your family in the future.

Where can I find more information about my particular PID?

IDFA has a range of information resources about immunodeficiency. We have hard copy and e-resources as well as links to other organisations in Australia and overseas which you may find useful.

Take a look at our Resources.

How are PID’s diagnosed?

Ongoing and persistent infections may be the first clinical sign of a suspected PID. Many people living with PID may also present with autoimmune complications. Your GP will refer you to an immunologist who can investigate further. Doctors will review your individual and family clinical history, run diagnostic blood tests (blood count, Immunoglobulin levels) and in some cases genetic testing.

What are my treatment options?

Immunoglobulin (Ig) replacement therapy
Ig therapy is one of the more common treatments among those living with a PID and helps protect patients from a range of infections. Ig’s (also known as antibodies) are necessary to fight infections caused by various germs and bacteria and come from plasma donated by healthy individuals. Donated plasma undergoes a rigorous screening process to ensure it is free from infectious disease. Ig therapy is an ongoing treatment and is administered by infusion either intravenously or subcutaneously.

IVIg – Intravenous immunoglobulin therapy is administered intravenously (ie injected into the vein) in hospital by a nurse every 2-4 weeks to maintain sufficient levels of immunoglobulin.

SCIg – Subcutaneous immunoglobulin therapy is self-administered by the patient at home, either using a pump or manually pushing after inserting a small needle under the skin Patients using SCIg therapy generally require more frequent infusions than those using IVIg therapy.

Infections are typically treated with antibiotics. In cases where infections don’t respond to standard medications, hospitalisation and treatment with intravenous antibiotics may be necessary. Some PID patients may need to take antibiotics long term (prophylactic antibiotics) to prevent infections from occurring as well as permanent damage.

Haematopoietic Stem Cell Transplant (HSCT) (a.k.a. bone marrow transplantation)
Stem cells are taken from bone marrow or cord blood of a healthy donor and transplanted into the PID patient to grow a new immune system. Stem cell transplantation is used to treat more severe types of PID’s such as Severe Combined Immunodeficiency (SCID) or Chronic Granulomatous Disease (CGD). HSCT is an involved procedure requiring long hospital admission and specific risks. While the aim of HSCT is curative, it is not always effective. Risks and benefits are explained in detail prior to treatment and consent.

Gene therapy
Gene therapy is a relatively new treatment and not yet widely available. Gene therapy replaces defective genes with working genes. A harmless virus is used to carry the genes into the body’s cells. In turn, the newly introduced genes trigger the production of healthy immune system enzymes and proteins. Increasing numbers of genes that cause PID are being discovered however gene therapy is still being refined.

Immunomodulatory drugs modify the response of the immune system and can be divided into two main groups: those that work by increasing the Immune system (immunostimulators) or those that work by suppressing the immune system (immunosuppressives). There are many different drugs within both categories and treatment depends on the specific needs caused by your PID.

People don’t believe me when I tell them I have a rare disease. How can I educate my family, friends, employer or school about my PID?

PID’s are rare and as a result, are not widely recognised in the general community. Explain that your condition leaves you more susceptible to infections and requires ongoing medical management. IDFA has plenty of resources freely available for you to download to support your case and to help you self-advocate.

Take a look at our Resources.

My PID/SID is impacting my ability to work, what can I do?

It depends on the severity of your illness; circumstances should be reviewed, and outcomes determined based on your individual case. Create a portfolio of information to support your case and if necessary, contact the Fair Work Commission to help you understand your rights and the rights of your employer. Once you have done this you can approach your employer and discuss alternative working arrangements such as working from home or amending/reducing your hours. Have an honest, open discussion and most of all remember to be positive.


Fair Work Commission – https://www.fwc.gov.au/

Fair Work Ombudsman – https://www.fairwork.gov.au/

Am I eligible for financial support eg NDIS support, carers payment?

This needs to be determined on a case-by-case basis by the relevant authorities. Our Links page has a list of useful website links for NDIS supports and carers payment etc.

Do I need to make changes to my child’s schooling?

Children and teenagers should be able to live as close to a normal life as possible with the right supports in place. These supports which include medical management, will vary over time so it’s important you have a healthcare plan and learning plan in place with the school. Communicate with the school regularly and provide them with information and resources about your child’s PID and any comorbidities. Your nurse specialist may be able to provide some formal education to the school so they may support your child’s learning.

What should I know about transitioning from paediatric to adult care?

Transition occurs when a PID child reaches the age of 16-18. After many years under the care of a paediatric immunologist and a healthcare team at a paediatric hospital the patient must transfer to an adult immunologist in an adult hospital. The environment is quite different and can take time to adjust. Some hospitals will offer the services of a Transition Co-ordinator to make the process as smooth as possible for the patient.

It’s important for parents/carers to empower their teenager through this process as they will become responsible for their own healthcare decisions once they turn 18. Encouraging your teenager to be actively involved in discussions and decisions concerning their treatments and various healthcare needs will boost their confidence.

From the age of 15 (approximately) it may be helpful if you accompany your child to clinic visits and then allow your child to spend some time without you in clinic, so they can practice speaking with health professionals and develop an understanding of what is expected of them in the future. Access to their own Medicare card may also be helpful. Ask your nurse specialist about resources for transitioning planning.

Where can I find support and connect with others living with PID’s or SID’s?

IDFA has a membership program available to patients living with a confirmed diagnosis of primary or secondary immunodeficiency. Carers of those patients are also eligible to become members. Through our membership you can access private Facebook groups and have access to IDFA patient meetings, conferences and more.