Introduction

Allergic reactions are reported to account for approximately 2–4% of all medical emergencies on commercial airline flights [1]. This number is likely to be higher, since acute asthma attacks are documented as a respiratory problem and not necessarily as a symptom of a severe allergic reaction [2]. In addition, two thirds of passengers do not inform flight crews of their allergic reaction during the flight [3]. When asked, 9% of peanut allergy sufferers reported experiencing an in-flight allergic reaction [4].

Severe allergic reactions on commercial flights are primarily caused by foods (peanuts, tree nuts, or seafood) and medications [1]. Anaphylactic shock is the most extreme form of allergic reaction. Within minutes, hives, swelling in the face and neck region, shortness of breath due to asthma, vomiting, and circulatory failure can develop, with fatal consequences. For some allergy sufferers, the thought of experiencing an allergic reaction of this kind while on a cramped aircraft without medical assistance is extremely frightening. This can also lead to disproportionate anxiety and challenges, particularly if no training and education on the causes and treatment of anaphylaxis have been provided [5].

People not suffering from allergies, on the other hand, often display no understanding for the potential risk to life posed by even small quantities of certain foods. Still today, individual case reports [6,7,8] attest to the unreasonable behavior of fellow travelers and considerable uncertainty among flight crews on how to deal with allergy sufferers due to a lack of appropriate information and structured guidelines from the airline. However, the in-flight risk of anaphylaxis could be significantly reduced by just a few simple measures taken by the patient themselves as well as the airline [9]. In 2016, the International Air Transport Association (IATA) published a communication, aimed at both allergy sufferers and airlines, containing recommendations on appropriate measures [10]. Air Canada and a number of other airlines have meanwhile largely adopted these guidelines [11].

To obtain information on the extent to which airlines operating in Germany have implemented the IATA recommendations and are now offering appropriate measures for passengers with severe allergies (e.g., peanut/nut allergy), the authors made a telephone inquiry to the German Federal Aviation Office (Luftfahrt-Bundesamt, LBA). They learned that there is no Germany-wide regulation and that those affected need to address their queries directly to the relevant airline. Travel agents and tour operators also need to contact the respective airline, or search through its website, in each individual case. The guidelines vary considerably here. Therefore, we conducted a written survey on this topic among the airlines operating in Germany.

Methods

In spring 2019, questionnaires (Table 1) were sent to 104 airlines operating in Germany. The questions could be answered quickly and simply by ticking a box. Airlines that failed to reply received two reminders within 3 months, with the questionnaire enclosed once again, both in German and English.

Table 1 Questionnaire sent to the airlines
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In a second step, the authors searched the airlines’ websites for information aimed at allergy sufferers. One cannot rule out the possibility that hidden information was overlooked and that not all airlines operating in Germany were recorded.

Results

The detailed results of the survey and online research are presented in Table 2. Data that came directly from the airlines are shown in normal type, while the information found by the authors is presented in italics. Table 2 provides information on 115 airlines. For 11 airlines, it became apparent only later that they also operate in Germany. These airlines did not receive questionnaires due to time constraints. As such, 104 airlines were contacted in writing up to three times with the questionnaire. Only four airlines returned their completed questionnaires. A total of 10 others responded in writing, albeit incompletely. The remaining airlines did not respond, despite two reminders.

Table 2 Results of the survey and online search
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Considerable variance was seen on the airlines’ websites. In all, 72/115 airlines provided information for allergy sufferers on their homepage, but mostly in insufficient detail. For 43 airlines, not even the search term “allergy” (or “Allergie”) produced any results on their websites.

Almost all airlines that make reference to allergies emphasize that they are unable to guarantee an allergen-free environment or a completely “nut-free flight” and therefore do not accept responsibility for in-flight allergic reactions. Nevertheless, 26 airlines do not serve snacks containing peanuts or offer to refrain from doing so for passengers with allergies. A total of 31 airlines continue to sell snacks containing peanuts or nuts. No data is available for the remaining airlines. Four airlines said that they provided a buffer area where necessary, while 12 do not. There are no data for the other airlines. Six airlines reported operating priority boarding for allergy sufferers, enabling these passengers to wipe down their seating area with their own wet wipes. Interestingly, two Japanese airlines offer their own special seat-cleaning service on request. Most airlines explicitly require affected passengers to inform them in advance of any allergies. However, how and when this should be done varies widely. Many airlines require a medical clearance certificate or a preprinted form to be filled out. Sometimes, these certificates are only accepted if preformulated sentences are used and time limits are observed. Medications carried in hand luggage need to be declared and approved in some cases, and information is also requested when boarding. Documents often also need to be provided in English.

A total of 15 airlines state that they offer varying degrees of strictly allergen-free meals for peanut/nut allergy sufferers. However, it is often not clear from this internet-based information whether meals may also contain traces of allergens. If an airline does offer special nut-free meals, these need to be ordered between 24 and 48 h before the flight. Cabin announcements are only allowed with the cabin manager’s authorization. Only five airlines carry adrenaline autoinjectors.

In summary, there are major differences between the airlines in terms of their approach to allergy sufferers. On a positive note, a small number of airlines are now addressing this problem in a targeted manner and have introduced risk-reduction measures. Some airlines make reference to the IATA communication. However, several airlines that are IATA members provide no information for allergy sufferers on their websites.

Discussion

The results of this survey clearly show that more information and action is needed in order to minimize the risk of life-threatening in-flight anaphylaxis for severe allergy sufferers. This is a task not only for the many airlines and their staff, but also for passengers with allergies, who should likewise be encouraged to make appropriate preparations to ensure low-risk travel. The best way to ensure that these preparations are made is if the airline requests them prior to the flight. To this end, all airlines should make relevant information available on their websites.

However, the IATA recommendations issued in 2016 need to be updated. For example, the European Medicines Agency (EMA) has recommended since 2015 that patients carry two adrenaline autoinjectors [12]. One rationale behind this is that the effect of adrenaline can significantly diminish within as little as 1 h, and a persistent anaphylactic reaction requires a further adrenaline dose to be administered. In addition, there have been recent reports of autoinjector malfunction, hence, the recommendation to carry two autoinjectors.

Moreover, several studies show that the risk of anaphylaxis due to inhalation of an allergen-containing aerosol, e.g., when opening a pack of nuts at some distance, is extremely low, thereby calling into question the need for all passengers on an aircraft to avoid peanuts outside a small buffer area [13]. However, up to 25-fold higher amounts of peanut protein were detected on aircraft tray tables when peanuts were served as a snack [14]. Another investigation detected peanut particles in aircraft air conditioning systems [15]. Therefore, dispensing with peanut-/nut-containing snacks on commercial flights remains desirable when allergy sufferers are traveling; however, decontamination measures are taking the foreground, e.g., priority boarding for allergy sufferers to enable them to clean the seat upholstery, armrests, and table surfaces in the row with their booked seats using their own wet wipes. Of apparent importance is the information that soap-based commercial wipes are better for peanut allergen removal than alcohol-based disinfection [16]. In the particular context of air travel, the allergic patient needs the acceptance, cooperation, and support of the airline and its flight attendants.

In coordination with the Anaphylaxis Scientific Working Group of the Society for Pediatric Allergy and Environmental Medicine GPA e. V., the authors recommend that all airlines operating in Germany provide readily accessible information for allergy sufferers on their websites or provide information upon request. Flight and travel agencies should inform passengers about this in good time. In order to make a constructive contribution in this regard, the authors have updated the IATA recommendations and made them available in English (see below) and in German (see German version: Allergo Journal 8/2020, www.springermedizin.de/allergo-journal). Not all of the following recommendations have been validated by extensive studies and, thus, merely represent the best possible evidence at the present time.

One element of the IATA recommendations that has not been adopted is the advice on aircraft emergency kits, since flight crew are not authorized to administer adrenaline in the form of an injectable solution. Although supplementing aircraft kits with adrenaline autoinjectors is evaluated positively [17], these are generally not available and the personnel are not trained in their use. Thus, the authors deem it all the more important to make passengers aware that they themselves need to ensure that they have sufficient emergency medication and are also able to use it accordingly. Children up to the age of 12–14 years need to be accompanied by a trained person [18]. It is also absolutely essential to provide information on the type and severity of the allergy in good time prior to booking a flight. The European Union air passenger rights stipulate that a passenger can be denied boarding if the airline has not been informed in advance of any severe allergies [19]. The following is the authors’ recommendation for an information sheet for passengers:

Information for passengers with severe allergies

To avoid in-flight medical emergencies, passengers are advised to fully comply with the following instructions.

Before travel

  1. 1.

    You should inform your physician of your intention to travel; he/she should check that your emergency kit is complete and has sufficient dose(s). An emergency kit consists of two adrenaline autoinjectors, one second-generation histamine‑H1 receptor antagonist, a systemic glucocorticoid, and, for asthmatics, also an emergency asthma spray. None of these medications should reach their expiry date before the return journey. Your physician needs to issue you with an emergency plan with instructions on allergy diagnosis, dose and route of administration of medications, as well as the need to take these on board; for travelling abroad, this plan should also be in English. Your physician should check whether you (as well as accompanying persons in the case of allergic children) are currently able to use the adrenaline autoinjector. Allergic children should never travel unaccompanied by a trained adult unless they have reached the age of 12–14 years and have demonstrated their ability to self-administer emergency treatment.

  2. 2.

    Taking out travel cancellation and travel interruption insurance, as well as travel health insurance, is recommended.

  3. 3.

    You must inform the airline of the risk of a severe allergic reaction in good time before booking. You should express the wish that, in order to reduce your risk on the flight:

    • For food allergies: you be granted priority boarding in order to clean seat upholstery, arm rests, and table surfaces in your row of seats with your own wipes (soap-based cleansing wipes are better for removing, e.g., residual nut than alcohol-based disinfectant wipes).

    • For peanut/nut allergies: no peanut-/nut-containing products should be sold or served.

    • The flight crew request that passengers in your immediate vicinity (a buffer area of at least one row of seats in front of and behind your seat) do not open or consume products containing peanuts/nuts (or the specific allergen). Since the risk of a severe allergic reaction from inhaling nut powder alone is very low, it does not appear necessary to inform all passengers unless such a reaction has occurred in the past.

  4. 4.

    If available, the person traveling should order allergen-free meals in good time. The airline cannot guarantee that these foods, or foods brought onto the aircraft by other passengers, are allergen-free. It is safer to bring your own food, whereby you need to check whether this is also permissible on connecting flights.

  5. 5.

    The airline should issue you with confirmation of the above-mentioned arrangements for presentation at check-in. If you do not inform the airline of your allergy until you are at the check-in, you may be denied boarding for safety reasons.

On the day of travel

  1. 1.

    Allow yourself plenty of time to go over your medications and special arrangements with security staff at the check-in. Although medications, including adrenaline autoinjectors, can be put through the scanner, they should always remain close to you and not stored, e.g., in the hand luggage compartment.

  2. 2.

    Ideally, those accompanying the allergy sufferer should clean arm rests, seats, and seat backs with wet wipes. Seat-back pockets should not be used, since food remnants that collect here are difficult to remove. You should also avoid using airline blankets or pillows.

  3. 3.

    You should request the flight crew to ask other passengers in the buffer area not to consume foods containing the relevant allergen. If no buffer area has been set up, you yourself can ask—but not demand—fellow passengers in your immediate vicinity to do so. You may need to ask to swap seats.

  4. 4.

    The flight crew should be immediately informed of any allergic reactions in order to request medical assistance and make other on-board emergency medications or oxygen available.