G Letter

What is gelatin

Gelatin is a protein product derived from collagen. It is added to some vaccines to act as a stabiliser to ensure they remain effective after manufacture. The type of gelatin used in vaccines (usually porcine in origin) is different from the gelatin used in foods (usually bovine in origin) and is highly purified.

Gelatin allergy

The incidence of anaphylaxis to gelatin is extremely low. Some individuals with an allergy to gelatin will react to the ingestion of gelatin. Others react only when a vaccine containing gelatin is injected or with the use of intraoperative hemostatic agents (e.g. surgical Gelfoam®).

Gelatin and vaccines

Gelatin in vaccines can cause allergic reactions therefore people with severe allergies to gelatin should avoid gelatin-containing vaccines.

Patients who report allergic reactions to the ingestion of gelatin should seek expert advice before receiving any vaccine containing gelatin.

Vaccines licensed in Australia which contain gelatin (porcine)

• MMRII® (measles-mumps-rubella)
• ProQuad® (measles-mumps-rubella-varicella)
• Varivax® (varicella)
• Zostavax® (varicella-zoster)
• Rabavert® (rabies)
• Merieux® (rabies)
• Vivotif® (typhoid)

If you have any concerns regarding a gelatin allergy and immunisation, please discuss with a healthcare professional or immunisation specialist.

Resources

• Children’s Hospital of Philadelphia: Vaccine Ingredients – Gelatin
• MVEC: Porcine gelatin and vaccines
• World allergy organisation: Ask the expert MMR vaccine
• Australian Immunisation Handbook: Components of vaccines used in Australia

What is it?

People with G6PD deficiency do not have enough of an enzyme (chemical) called glucose-6-phosphate dehydrogenase (G6PD). It is a genetic disorder which predominantly occurs in males.

Without G6PD, red blood cells are destroyed when exposed to certain foods, infections, medicines or chemicals. Red blood cells breaking down in excess can result in haemolytic anaemia (reduced number of red blood cells), jaundice (yellow skin or eyes), shortness of breath and other symptoms.

G6PD is an inherited condition and cannot be spread from one person to another. Managing G6PD deficiency involves avoiding foods and medications that can trigger the episodes of the condition.

G6PD deficiency and vaccines

Vaccination is an important way of preventing the potential triggers that viral and bacterial infections can be in people with G6PD deficiency. Vaccines have not been identified as a medication to avoid. People with G6PD deficiency can be safely immunised in community settings without the need for additional monitoring.

G6PD deficiency and COVID-19 vaccines

Like routine vaccines, COVID-19 vaccines can be safely administered to people with G6PD deficiency. Clinical trials and real-world evidence have not identified any specific concerns regarding COVID-19 vaccines and people with G6PD deficiency.

There is no evidence that a particular brand of COVID-19 vaccination is preferred for people with G6PD deficiency. 

Resources

• The RCH kids health information: G6PD
• Healthdirect: G6PD deficiency

Background

Guillain-Barre Syndrome (GBS) is an autoimmune condition whereby the body’s own immune system can attack the nerves, damaging the myelin (insulating layer) and sometimes the axon (nerve fiber). This damage can result in symptoms of muscle weakness, altered sensation, numbness and paralysis.

The rate of GBS is approximately 2 in every 100,000 people per year. The syndrome is often triggered following a viral or bacterial illness usually occurring 1-3 weeks prior to symptoms developing. As an example, ‘wild-type’ influenza and campylobacter are infections known to be associated with GBS.

Symptoms usually start in the lower extremities and progress up the body over a few days or weeks. There is no known cure but therapies include intravenous immunoglobulin. Most cases spontaneously recover although this may take from 6 months to 2 years. Approximately 10-15 percent of GBS cases can result in permanent disability.

GBS and influenza vaccines

Influenza vaccination has been identified as a possible cause following H1N1 containing vaccines, but the evidence is variable and at a very low rate, definitely lower than the rate of GBS caused by ‘wild type’ influenza. As per the AusVaxSafety clinical resources flow chart  [see resources], influenza immunisation is generally not recommended for people with a history of GBS occurring within 6 weeks of receiving a previous influenza vaccine. However specialist immunisation advice should be sought to discuss the potential benefit of vaccination and the risk for GBS recurrence post vaccination or GBS recurrence post influenza disease. There are no concerns administering influenza vaccines to patients who have a history of developing GBS more than 6 weeks following an influenza vaccine.

GBS and meningococcal vaccines

There is no increased risk of developing GBS after receiving meningococcal vaccinations. People with a history of GBS can safely receive meningococcal vaccines. It is also safe for them to receive all of the other routine National Immunisation Program (NIP) and travel vaccines as required.

GBS and COVID-19 vaccines

GBS has been reported to occur in individuals following both COVID-19 infection and COVID-19 vaccination. Intensive post-licensure surveillance and investigations by the TGA and other international vaccine regulators, has shown a growing body of evidence of a possible link between GBS and Vaxzevria (AstraZeneca). In response to this, GBS has been listed as a precaution for those receiving Vaxzevria.

Individuals who have previously been diagnosed with GBS can receive COVID-19 vaccines. Specialist advice from a treating neurologist or immunisation specialist may be considered to discuss the benefits and risks of vaccination.

GBS and Shingrix®

Preliminary data from the US suggests that there is a very rare risk of GBS ocurring in individuals who have received the shingles (herpes zoster) vaccine, Shingrix® (an additional 3-6 cases of GBS per million doses of vaccine administered). GBS has also been reported following shingles disease. The benefits of vaccination outweigh the risk of GBS.

Resources

• AusVaxSafety Clinical Resources: Approach to influenza vaccination in patients with a history of Guillain-Barre Syndrome
• Australian Immunisation Handbook: Influenza chapter
• Better Health Channel: Guillain-Barre Syndrome
• CDC: Vaccine Considerations for People with Underlying Medical Conditions