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Desensitization

Desensitization

Allergic vaccination

Allergen-specific immunotherapy (specific IT)

these three denominations are synonyms.

Indication

Desensitizations are well tolerated, even by children. It can be undertaken at any age, as from 6 years old.

This treatment is an excellent alternative to medication. It is specially appreciated when medication is not an option or not desired.

Vaccination can cure allergies to pollens, cat dander, house dust-mites, bee or wasp venoms, etc. Extracts used for vaccination contain no other medication which might require metabolisation (no anti-histamin for instance).

Desensitization is the only known treatment option that modifies allergy disease process, with a possible chance of curing the disease whereas other therapies merely suppress the symptoms.

Objectives

  • Desensitizations have been carried out for a long time
  • The extracts used have tremendously improved over the past 15 years and results are excellent (significant improvement of symptoms for most patients, complete recovery for 60 to 70% )
  • Symptoms are nearly always improved and the progression or aggravation of allergies is put to a stop
  • The purpose of desensitizations is to obtain final and complete recovery, i.e. absence of allergic reaction(s) when in contact with the incriminating allergen
  • Desensitizations are mostly indicated to reduce severity of asthma as well as improve life quality
  • Multi-allergens desensitizations reduces chance of developing new sensitisations
  • Concerning wasp or bee venoms, the objective is to prevent a potentially life-threatening reaction in case of sting (since desensitization induces a tolerance and halts allergy progress)
  • This treatment reduces the immune system’s reactivity (Ige antibodies will no longer react during contact)
  • After a desensitization, medication is hardly necessary (possibly during high pollen peaks only)

Results

  • Desensitizations can reduce the need for medication, severity of symptoms or eliminate hypersensitivity
  • Improved quality of life
  • Reduction of days off school / work
  • Reduction of allergic asthma
  • Long-term remission of allergic symptoms
  • Obvious results can be noted as from the first year of desensitization :
    • Patients allergic to pollens mention feeling much better and being able to enjoy outdoor activities during spring
    • Patients allergic to house dust-mites breathe better, their nose is no longer blocked and their sleep improves
    • Cat-allergic patients suffer fewer symptoms
    • Wasp or Bee allergic patients no longer need to worry outdoors, in case of a sting
    • Improved resistance to viruses
  • Generally speaking, the quality of life improves in such a manner that this overrules the treatment’s inconvenience (regular injections)

Methods of desensitization

  • Subcutaneous injections (under the skin) with standard allergen extracts are highly efficient, with obvious improvement and potentially complete recovery. Extracts’ quality, quantity and purity are controlled and constant. This treatment also helps prevent any further allergies.
  • Sub lingual drops or tablets (under the tongue) are less effective. They must be taken daily, also during a number of years.

Description of a desensitization by injections

  • Needles are very thin and sterile
  • Subcutaneous injections are made in the fat at the back of the upper arm. You can hardly feel them (not very painful)
  • Patients must stay in the clinic during the 30 minutes following their desensitization shot, in case a reaction were to occur (which is rare). During this 30 minutes wait, you can rest, read, drink something in the waiting room. The nurses keep a close eye on possible reactions and inform the Doctor in case of need. After this delay, delayed allergic reactions which could occur are extremely rare and normally not dangerous.

Organisation

  • In any desensitization, there is a first period of “induction” during which the patient is vaccinated weekly with increasingly larger doses of allergen with the aim of inducing immunologic tolerance to a “normal” level. For pollens, induction can begin in September, so as to be ready for the following pollinic season. For house dust-mites or cats, induction can be carried out at any time in the year.
  • After induction is completed a “maintenance” phase begins, by monthly booster injections, during 3 to 5 years. This maintenance period enables to keep the level of tolerance and force it into the immune system’s memory. These monthly shots are relatively easily organised and can be arranged around holidays or travels.
  • We have two desensitization protocols:
    • Yearly : results are in proportion with quantity injected and length of treatment. Highly efficient
    • Pre-seasonal (autumn-early spring) : only for pollens. Less efficient due to smaller quantities injected and shorter treatment
  • A special note for pollen desensitization : during pollinic season, doses are reduced for comfort, and increased back to maintenance dose after pollination

Length of treatment

Between 3 and 5 years, so as to register the long-term result in the immune system memory (long-term remission of allergic symptoms)

  • Minimum treatment : 3 years
  • Additional 2 years (recommended by OMS – WHO) indicated if treatment is considered efficient and if symptomns have lessened : in this case 2 additional years will consolidate the results and the risk of recurrence is reduced significantly.
  • Apart from the induction period (once a week injections) the desensitization is fairly easy to organise and does not require much time (30 minutes once a month).

There are no particular side effects to this treatment apart from the potential allergic reaction. No metabolic risks or side effects to organs.

In case of pregnancy, it is possible to continue maintenance doses of vaccination, but never increased (due to risk of allergic reaction which would require additional medication).

Possible side effects

  1. Local reaction: not an allergic reaction, but rather an inflammatory reaction post-injection or a granuloma due to the product. This can be a little painful and require local treatment (cold-pack, antihistaminic, analgesic). Unpredictable and not automatic, most desensitized patients never suffer from them.
  2. Anaphylactic reaction: these rare allergic reactions are under strict control. They appear during the 30 minutes following the injection, whilst still in the clinic, and are immediately taken care of by the MD. Possible reactions range from urticaria, angio-oedema, rhinitis, conjunctivitis, asthma, eventually leading to weakness or faintness in the worst case scenario.
  3. Prevention: A few antihistaminic tablets in the purse, as well as a bronchodilatator for asthmatic patients are required. Other medication can remain at home. A prescription with all necessary medication in case of need is provided each year.

Spirometry (lung function) & breathing tests: to detect asthma and check treatment results. Preferably carried out during pollination. Normally once a year or more for severe asthma. Spirometry is two-fold: normal expiration measurement followed by a bronchodilatation (medication); then a second measurement after 20 minutes (for evidence of bronchial inflammation).

Health check-up / blood test : useful for treatment results follow-up and also to prevent other ailments.

CHILDREN

  • Allergies can appear at all age. We usually avoid desensitizations before the age of 6, unless the family is very allergic (in which case it is possible as from 4 years old)
  • Children cope surprisingly well with this treatment, apart from initial fear of the first injections
  • As soon as they understand their treatment, they usually come by themselves for their injections (i.e. just after school)
  • They are pleased to feel better and no longer suffer from their allergies. They can breathe more easily and play outdoors with their friends without trouble
  • No ill effects on their growth

PREGNANCY

  • No toxicity for the foetus. Injections may continue during pregnancy
  • No side effects on breast-feeding nor for the baby
  • During pregnancy, however, vaccination doses will not be increased for fear of anaphylactic reaction which would require medication and could upset the mother-to-be
  • If the patient agrees to continue her desensitization during her pregnancy, only the acquired maintenance dose is continued
  • For pollens, it will simply be increased after giving birth.
  • In case the patient prefers to halt her treatment during pregnancy, it will be possible to implement it back after the baby is born (no problems during breast feeding)

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