Anthrax vaccine

Anthrax is caused by a spore-forming anaerobe; humans become infected through contact with a sick animal, contaminated livestock products, or the remains of dead animals. In Russia, there are about 8,000 anthrax cattle burial sites, primarily in the Volga, Central, and Southern Federal Districts. The spores are highly resistant and can spread over long distances.

Anthrax occurs in cutaneous, intestinal and most severe pulmonary forms, the latter developing with inhalation infection. The incubation period is from several hours to 12 days. Mortality with untreated cutaneous form is 5-20%, with intestinal - 25-75%, pulmonary - even higher. Unlike animals, a sick person does not excrete the pathogen and therefore is not contagious to others, which limits the possibilities of using anthrax for bioterrorism purposes.

In Russia, isolated cases of anthrax are observed annually (3 in 2007). In the USA, the pathogen and its spores have been used for bioterrorism purposes. In Russia, vaccination is administered in enzootic areas. Two vaccines have been registered:

Anthrax vaccine, live, dry, for subcutaneous and scarification use — live spores of the STI vaccine strain, lyophilized in a 10% aqueous sucrose solution. Release form: 1.0 ml of vaccine in an ampoule (200 or 100 doses for subcutaneous or 20 or 10 doses for cutaneous vaccination, respectively) + 1.5 ml of solvent for cutaneous use — 30% glycerol solution. Anthrax vaccine is stored and transported at a temperature of 2-10° (at 25° — no more than 20 days).

The combined lyophilisate anthrax vaccine for subcutaneous administration is a mixture of live spores of the STI-1 vaccine strain and purified concentrated protective anthrax antigen (PA) adsorbed on aluminum hydroxide gel. The preparation is lyophilized in ampoules from an initial volume of 2 ml (10 doses). When adding 0.9% sodium chloride solution, a homogeneous suspension is formed. Release form: dry preparation (10 doses) in ampoules, solvent - saline solution in 6 ml ampoules. Liquid preparation of 5 ml (10 doses) - in ampoules or vials. The pack contains 5 ampoules (vials) of liquid vaccine or 5 ampoules of dry vaccine and solvent. The vaccine is stored at a temperature of 2-6 °, transported at 2-10 °. The shelf life of the dry vaccine is 3 years, the liquid vaccine - 2 years.

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Immunological properties of anthrax vaccine

Both vaccines are used in adolescents from 14 years of age and adults, they cause the formation of intense immunity lasting up to 1 year.

Anthrax vaccine administration and dosage

Scheduled vaccination is carried out by the cutaneous method in the first quarter of the year, i.e. before the most dangerous spring-summer season. Primary vaccination is carried out with both vaccines, revaccination is carried out once a year subcutaneously with a vaccine for subcutaneous and scarification use. The first three revaccinations are carried out by administering 0.5 ml (50±10 million spores), and all subsequent ones - every two years in a volume of 0.5 ml (5±1 million spores). Unscheduled vaccination is better done subcutaneously.

The live dry anthrax vaccine for subcutaneous and scarification use is used in 2 ways. Primary immunization (from the age of 14) - twice with an interval of 20-30 days. For all vaccinations, the cutaneous dose is 0.05 ml and contains 500 million spores, one subcutaneous dose of 0.5 ml - 50 million spores.

Vaccination by the cutaneous (scarification) method is performed on the outer surface of the middle third of the shoulder through 2 drops of the diluted vaccine at a distance of 3-4 cm, making 2 parallel incisions 10 mm long, followed by rubbing for 30 s. The contents of the ampoule are resuspended in a solvent immediately before use: 0.5 ml in an ampoule with 10 cutaneous doses, 1.0 ml with 20 doses. The administered vaccine, stored aseptically, is used within 4 hours.

Vaccination against anthrax by the subcutaneous route: the preparation is resuspended in 1.0 ml of sterile 0.9% sodium chloride solution, then transferred to a sterile vial with 99 ml of the same solution for an ampoule with 200 subcutaneous doses or with 49 ml for ampoules with 100 doses. The vaccine is administered subcutaneously in the area of the lower angle of the scapula in a volume of 0.5 ml.

Vaccinations with combined dry and liquid anthrax vaccine for subcutaneous use are carried out once. 5.0 ml of sterile saline solution is introduced into an ampoule (vial) with 10 doses, one dose (0.5 ml) contains 50±10 million spores and 0.35±0.05 mg of PA protein. The vaccine from an opened ampoule, stored aseptically, is used within 4 hours. The anthrax vaccine is administered into the area of the lower angle of the left shoulder blade.

Contraindications to vaccination against anthrax

In addition to the general contraindications for live vaccines, the following are taken into account:

• systemic connective tissue diseases;
• common recurrent skin diseases;
• diseases of the endocrine system.

The interval between anthrax vaccination and the administration of other anthrax vaccines should be at least one month.

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Reactions to anthrax vaccine

When applied topically, a local reaction appears after 24-48 hours in the form of hyperemia, a small infiltrate followed by crust formation. When both vaccines are administered subcutaneously, after 24-48 hours there may be a small hyperemia at the injection site, less commonly an infiltrate of up to 50 mm. A general reaction to the anthrax vaccine occurs rarely: on the first day, malaise, headache, temperature up to 38.5° and enlarged lymph nodes.

Post-exposure prophylaxis of anthrax

The causative agent of anthrax is resistant to co-trimoxazole and many cephalosporins; in case of suspected contact with it, adults are recommended to take ciprofloxacin or doxycycline, and children are recommended to take amoxicillin 80 mg/kg/day (up to 1.5 g/day).