An Update on Immunotherapy for Environmental (inhaled) Allergies
Allergic rhinitis, better known as 'hayfever', affects at least a third of New Zealanders. No one really knows why, but allergies to things like pollen, house dust and even cat’s fur, have become a lot more common in the last 50 years or so.
Symptoms include a watery, runny nose; itchy red, watery eyes and nose; a blocked nose; bouts of sneezing; and often needing to clear the throat. Some people can also get skin symptoms such as hives, and even asthma attacks.
Many ‘hayfever’ sufferers don’t actually realise how much of an impact it is having on their health and quality of life. We may put up with the itchy eyes and constant runny nose during the day as ‘normal’ but annoying. Sneezing is a concern because of the distraction it causes – and these days because of the worried looks we get in this new COVID-19 era - however, we don’t often connect our constantly-blocked nose as the cause of our headaches, or ongoing tiredness from poor sleep.
In children, these symptoms can have a long-lasting effect. Studies have shown that lack of sleep reduces their ability to concentrate and learn at school; and may adversely affect their behaviour and development. Long term, this can reduce their overall education attainment, and potentially, employment opportunities, income, and well-being as adults.
Uncontrolled hay fever may also increase the risk of sinusitis and commonly leads to worse asthma control as the nose is important for humidifying, filtering and warming the air that goes to our lungs.
While medications such as cortico-steroid nasal sprays and antihistamines can be effective in reducing symptoms in most cases, allergic rhinitis is a chronic condition. It may therefore continue through your lifetime, and symptoms occur whenever you are exposed to the allergens concerned. Given avoiding most environmental allergens is difficult, medications will usually need to be taken on a daily basis.
Specific Allergen Immunotherapy (AIT)
Specific Allergen Immunotherapy (AIT) is often recommended by specialists for the treatment of allergic rhinitis due to allergy to pollen, dust mite or animal dander when:
How does it work?
Three years of AIT can result in at least five to 10 years of benefit. Symptoms may sometimes return after this time, and patients may choose to have a repeat AIT course if desired.
There are two different forms of AIT:
Pros and Cons:
For some forms of SCIT, side-effects include localised swelling at the site of the injection, which can be treated with non-sedating oral antihistamines or ice packs. More serious reactions (such as anaphylaxis) are uncommon. However, predicting who might have serious reactions is difficult. Patients are normally advised to remain in their doctor's surgery for at least 30 minutes after the injection(s).
The safety profile for SLIT for environmental allergens is reported as excellent, although patients sometimes experience transient mouth or abdominal symptoms.
Given the length of time AIT takes, compliance with the treatment can be an issue. For both methods, the treatment involves regular doses for at least three years and up to five years. SCIT needs to be performed at a doctor’s surgery and the course of treatment can be disrupted if the patient is not able to attend once a month for any period of time. This is not an issue for those on SLIT, where the daily dose can be taken at home, although compliance has actually been found to be poor compared to SCIT.
For both SCIT and SLIT, cost may be an issue. No products available in New Zealand are currently funded by PHARMAC [unlike bee and wasp venom immunotherapy which is fully Pharmac-funded].
Injection immunotherapy is less expensive than sublingual immunotherapy and currently costs around $700 (incl GST) for a year’s treatment for the single allergen kits. For the multiple allergen kits, the yearly cost is around $900 but that allows up to three allergens to be given in the one injection. Note, the clinic costs for giving the injections also has to be added (if done in private practice, although if done by the local paediatric hospital service, this may be free of charge). Special ultrafine syringes come with the vaccine and are free of charge.
Sublingual (by mouth) immunotherapy costs about $260 per three months per allergen. Grass pollen allergies can be treated for half the year at half the cost but house dust mite or other year-round allergies, like cat, require treatment continually, so this will cost approximately $1125.00 per year for each allergen (max 2).*
*All immunotherapy costs estimated as of October 2020