Adjuvants are added to some vaccines to increase the ability of the antigen to stimulate the body's immune response (Centers for Disease Control & Prevention 2017). Substances used as adjuvants include aluminium salts (e.g. aluminium hydroxide) and mineral oils. It is not possible to tell visually which type of adjuvant is included in a particular vaccine. A product’s summary of product characteristics (SPC) lists all the ingredients, including adjuvants.
Mineral oils are derived from petroleum distillation. Oils used as adjuvants contain an optimal number of carbon atoms, representing a balance between an inadequate immune response (from an oil with a high carbon number) and an unacceptable rate of adverse reactions (from an oil with a low carbon number) (ExxonMobil 2017). Light paraffin oil is the mineral oil most commonly included in veterinary vaccines (VMD Product Database). Sometimes the SPC lists the adjuvant as liquid paraffin or light liquid paraffin, sometimes as ‘mineral oil’ and sometimes as a brand name (e.g. Amphigen Base, Drakeol, Montanide, Marcol). Hydrogenated polyisobutene is another mineral oil adjuvant.
Mineral oil is a tissue irritant. It can cause significant harm in the form of local damage and/or prolonged pain at self-injection sites, commonly the hand (Kennedy & Tetlow 2004; Jones 1996). Such injuries, if not permanent, have the potential to be disabling for some time. Case reports have described extensive chronic granulomatous inflammation in the thigh requiring major surgical debridement, and chronic inflammation and sterile abscess formation in the hand requiring surgical drainage and corticosteroids for eventual healing (Jones 1996). The available information does not indicate that risk is related to the quantity injected. Therefore all self-injection with mineral oil should be treated seriously and urgently. There is also the potential risk of infection or adverse effects from other vaccine constituents (Burke et al 2017).
The UK Veterinary Medicines Directorate (VMD) warns: “You must take particular care when using vaccines with a mineral oil adjuvant. It is very important to seek immediate medical attention if you injure yourself with the needle whilst using one of these products. Make sure you take the product information leaflet with you, so that you receive the correct medical attention.” (VMD 2014)
The SPCs of some products (e.g. Aftopur DOE foot and mouth vaccine) contain specific advice: “To the doctor: This product contains mineral oil. Even if small amounts have been injected, accidental injection with this product can cause intense swelling, which may, for example, result in ischaemic necrosis and even the loss of a digit. Expert, PROMPT, surgical attention is required and may necessitate early incision and irrigation of the injected area, especially where there is involvement of finger pulp or tendon.”
There is limited published evidence on the frequency of accidental self-injection (Burke et al 2017). In the UK there is no formalised mechanism for reporting self-injection events. However, over 30% of adverse events to veterinary medicines in humans reported to the VMD concern such incidents (Burke et al 2017). In other countries, rates of between 9 and 75 injuries per 100 person-years of practice have been reported (Burke et al 2017).
A report from the USA involved 199 vets who administered Mycobacterium paratuberculosis vaccine (containing mineral oil) to cattle; 19 reported self-injection events, 63% of which took place during the injection process. The reactions varied from a small nodule persisting for 4–6 months to painful inflammation of a finger persisting for 24 months (Patterson et al 1988).
Most of the mineral oil-containing vaccines are for food production animals, mainly cattle, chickens, pigs, sheep and salmon. There are two for goats; one for rabbits (rabbit haemorrhagic disease virus type 2 [RHDV-2]: Eravac*), one for pigeons, one for turkeys and one for dogs (Eurican herpes 205) (VMD product database). Most (but not all) of the products categorised as ‘emulsion for injection’ in the VMD product database contain mineral oil.
* water-based vaccines against RHDV2 are licensed in France (Filavac VHD KV+C) and Spain (Novarvilap). The VMD has stated that it will accept applications to import unauthorised medicines into the UK to treat RHDV2 if Eravac is not available or suitable. (Gov.UK)
- Be aware of the risks!
- Make sure you are familiar with any risks specified in the SPCs for all medicines you use.
- Review if any vaccines containing mineral oil in current use could be replaced with alternatives. In keeping with UK Health and Safety Executive (HSE) advice, decide which of the range of authorised treatments is best to prevent or control the condition in animals but poses the least risk to people and the environment; use less hazardous products where possible (HSE 2017)
- If use of a mineral oil-containing vaccine is unavoidable, perform a risk assessment. This should include ensuring that all staff members are aware of the risks and what to do in the event of accidental self-injection.
- Develop a safe injection technique. Remind yourself not to be distracted. Have a trained assistant or use the correct equipment to handle or restrain the animal. Uncap the syringe needle and use immediately. Inject the entire dose into the patient to avoid any significant volume remaining in the syringe. Do not recap the needle after use as this can result in self-injection (Burke et al 2017). Instead, immediately put it in a suitable sharps container for safe disposal. Gloves may be worn but are unlikely to be strong enough to prevent needle puncture. In practice, gloves can result in loss of dexterity needed for a slick injection technique to an animal which may be moving or liable to move.
- If there is any puncture of the skin, or possible injection of even a small quantity of the vaccine, seek hospital help immediately. Take the product information leaflet with you. Do not drive yourself in case you become unwell.
- Report the event: in the practice accident book; to the health & safety responsible person in the practice; to colleagues so they are aware; and the VMD via the online reporting form. (NB fax reports are no longer acceptable).
- Set up a clinical debriefing session for all relevant staff to identify lessons to learn and preventive actions. Share the knowledge with colleagues.
Some vaccines contain mineral oil, which can cause serious harm if self-injected. Self-injection injuries are not uncommon and are probably under-reported. In the event of self-injection, prompt assistance must be sought to prevent unnecessary damage. Veterinary medicine summaries of product characteristics (SPCs) contain important information about risks so should be read before use. If there are equivalent vaccines that do not contain mineral oil, and so carry less risk of harm, they should be preferred. Share knowledge about the risks of mineral oil self-injection with colleagues. If self-injection occurs, act promptly and ensure the relevant lessons are learned and shared.
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Goal of activity: Update knowledge; help clinical decision-making.
Authors/disclosures: Veterinary Prescriber editorial team/no conflict of interest.
Specific learning objectives: to improve knowledge and understanding of the risks associatied with mineral oil-containing vaccines and what you need to know to keep safe.
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Aftopur Doe. Summary of Product Characteristics. Essex: Merial Animal Health Ltd; September 2014.
Burke F et al. Needlestick and inoculation injuries in veterinary and animal workers. In Practice 2017; 39: 138-41.
Centers for Disease Control & Prevention. Vaccine Adjuvants. 2015 [updated 2016]. [Accessed 23 March 2017].
Exxon Mobil Corporation. White oils as adjuvants in animal vaccines. 2014. Available from [Accessed 23 March 2017].
Health and Safety Executive. Veterinary medicines. Safe use by farmers and other animal handlers. 2012. [Accessed 23 March 2017]
Jones DP. Accidental self inoculation with oil based veterinary vaccines. N Z Med J 1996;109: 363-5.
Kennedy KJ, Tetlow L. Test and teach. Chronic soft tissue inflammation following accidental inoculation with a sheep vaccine. Pathology 2008; 40: 711-3.
Patterson CJ et al. Accidental self-inoculation with Mycobacterium paratuberculosis bacterin (Johne's bacterin) by veterinarians in Wisconsin. J Am Vet Med Assoc 1988; 192:1197-9.
Veterinary Medicines Directorate: Pharmacovigilance in the United Kingdom Annual Review 2014. [Accessed 27 March 2017]