Vaccine Academy › Vaccine School › Special use
Content current as of October 12, 2026. AI-assisted draft; not yet reviewed by a licensed pharmacist. Current CDC schedules: immunization schedules.
- The disease and why it matters
- Video and figures
- Get CE credit
- Products available
- Who should get it
- Dosing and schedule, including catch-up
- Administration
- Storage and handling
- Contraindications and precautions
- Safety and adverse events
- Special populations
- Counseling pearls for the pharmacy counter
- Common patient questions
- References
The disease and why it matters
Anthrax is a serious infectious disease caused by Bacillus anthracis bacteria (or other Bacillus species that produce anthrax toxin), occurring naturally in soil and commonly affecting domestic and wild animals around the world; it is not contagious, and exposure and illness in the United States are rare, though people can also be exposed during a bioterrorism event. [1]
People can contract anthrax by contact with infected animals or contaminated animal products (meat, wool, hides, hair), by consuming contaminated food or water, by exposure in a laboratory that handles B. anthracis, or in a bioterrorism attack. [1]
Mortality even with treatment ranges from less than 2% for cutaneous anthrax to 45% for inhalation anthrax and 92% for anthrax meningitis; B. anthracis is a tier 1 select agent and one of the bioterrorism agents considered most likely to be used because it is relatively easy to acquire, mass produce and disseminate as spores via aerosolization. [2]
Cutaneous anthrax, the most common form, occurs when spores get into the skin (usually through a cut or scrape) and typically develops 1 to 7 days after exposure; without treatment up to 20% of people with cutaneous anthrax die, and with appropriate antibiotic treatment almost all survive. [1]
Video and figures
Video
Get CE credit
No free accredited CE activities for this topic have been confirmed yet.
RxEvidence is not an accredited continuing education provider and does not award CE credit. These are links to activities offered by others.
Products available
Two anthrax vaccines are licensed: BioThrax (anthrax vaccine adsorbed, AVA), approved for pre-exposure prophylaxis in persons at high risk of exposure and for post-exposure prophylaxis in conjunction with antibacterial drugs, and CYFENDUS (anthrax vaccine adsorbed, adjuvanted), indicated only for post-exposure prophylaxis; both are for persons 18 through 65 years of age. [3] [4]
| Vaccine | Manufacturer (FDA page) | Use | Route and dose | Initial U.S. approval |
|---|---|---|---|---|
| BioThrax (AVA) | Emergent BioDefense Operations Lansing LLC [5] | Pre- and post-exposure prophylaxis, ages 18 through 65 | Intramuscular or subcutaneous; each dose 0.5 mL [3] | 1970 [3] |
| CYFENDUS (AVA with CpG 7909 adjuvant) | Emergent BioDefense Operations Lansing LLC. [6] | Post-exposure prophylaxis only, ages 18 through 65 | Intramuscular; two 0.5 mL doses two weeks apart [4] | 2023 [4] |
Cyfendus contains the same active ingredient as BioThrax with a CpG 7909 adjuvant that BioThrax does not contain; the efficacy of both vaccines for post-exposure prophylaxis is based solely on studies in animal models of inhalational anthrax. [4] [3]
The BioThrax label is revised 11/2025 while the FDA BioThrax product page is marked content current as of 07/06/2023 (its earliest approval letter in the set retrieved is dated November 5, 2025); the Cyfendus page is marked content current as of 11/06/2025. The 2019 ACIP report describes AV7909 (the antecedent of Cyfendus) as an investigational vaccine. [3] [5] [6] [2]
Who should get it
CDC / ACIP (MMWR Recommendations and Reports, 2019)
As of December 1, 2019
ACIP previously recommended AVA pre-exposure prophylaxis (PrEP) for persons at high risk for exposure to B. anthracis (for example members of the U.S. military deployed to areas designated by DoD as high risk, laboratory workers who work with high concentrations of B. anthracis, and farmers, veterinarians and livestock handlers who might handle infected animals or contaminated animal products); because of the lack of a quantifiable risk, emergency and other responders are not recommended to receive routine PrEP, but may opt to receive the vaccine on a voluntary basis. [2]
CDC VIS (January 8, 2020 edition)
As of January 8, 2020
The VIS says anthrax vaccine is approved by FDA and recommended for adults 18 through 65 years of age who are at risk of exposure, including certain laboratory workers who work with Bacillus anthracis, people who handle potentially infected animals or their carcasses, and some military personnel (determined by the Department of Defense). [7]
For people with suspected or known exposure, ACIP recommends AVA for adults aged 18 to 65 years given in conjunction with a course of antimicrobials to prevent infection after exposure to aerosolized B. anthracis spores; the vaccine and prophylactic antibiotics should be given immediately to patients who might have been exposed. [2] [1]
Persons not included in the FDA-approved post-exposure indication (children, pregnant women, nursing mothers and adults 66 years and older) would receive AVA for post-exposure prophylaxis under appropriate emergency use regulatory provisions. [2]
Dosing and schedule, including catch-up
| Use | Source | Schedule |
|---|---|---|
| Pre-exposure prophylaxis (high risk) | BioThrax label | Intramuscular primary series at 0, 1 and 6 months; boosters 6 and 12 months after completing the primary series and at 12-month intervals thereafter; in persons at risk for hematoma after intramuscular injection, subcutaneous schedule at 0, 2, 4 weeks and 6 months with boosters 6 and 12 months after the primary series and every 12 months [3] |
| Pre-exposure prophylaxis (not currently high risk) | ACIP 2019 | A booster dose of AVA may be given every 3 years to persons not at high risk who have previously completed the 3-dose primary and 2-dose booster series and want to maintain protection [2] |
| Post-exposure prophylaxis, BioThrax | BioThrax label | Subcutaneous, 0.5 mL at 0, 2 and 4 weeks post-exposure, combined with antimicrobial therapy [3] |
| Post-exposure prophylaxis, CYFENDUS | CYFENDUS label | Two 0.5 mL doses intramuscularly two weeks apart, with recommended antibacterial drugs [4] |
ACIP (2019) says that if the PrEP schedule is interrupted the series does not need to be restarted and documentation of seroconversion is not required; after the priming series is completed, people can work in high-risk areas of exposure with appropriate personal protective equipment and biosafety measures, and a 30-day course of antimicrobial post-exposure prophylaxis is recommended if biosafety or respiratory protection measures are breached, regardless of whether PrEP was completed. [2]
For PEP, ACIP prefers the subcutaneous route (higher antibody concentrations at 4 weeks) but, during a large-scale emergency response, AVA may be given intramuscularly if the subcutaneous route poses significant challenges; if the schedule is interrupted the series does not need to be restarted, and doses inadvertently given intramuscularly do not need to be repeated. [2]
ACIP recommends dose-sparing PEP regimens if supply is insufficient (2 full doses expands supply by 50% and 3 half doses by 100%), with the 2-dose schedule at least 2 and at most 4 weeks apart; in immunocompetent adults 18 to 65 years antimicrobial post-exposure prophylaxis can be discontinued 42 days after starting the vaccine if AVA is given on schedule, otherwise antimicrobials continue for 60 days, and children, pregnant women, adults 65 years and older and immunocompromised persons continue antimicrobials for 60 days with AVA. [2]
Because the MMWR report pre-dates Cyfendus licensure, its antimicrobial-duration guidance is written for AVA; the Cyfendus label states that it is indicated for post-exposure prophylaxis in conjunction with recommended antibacterial drugs, and these pages do not give a Cyfendus-specific antimicrobial duration. [2] [4]
Administration
- BioThrax: shake the vial thoroughly so the suspension is homogeneous during withdrawal; administer pre-exposure doses intramuscularly into the deltoid muscle (over the deltoid if subcutaneous) and post-exposure doses subcutaneously over the deltoid muscle; discard the multiple-dose vial within 28 days after the stopper is first pierced. [3]
- CYFENDUS: gently swirl or roll the vial to ensure a homogeneous milky-white suspension and do not shake (to avoid foaming); inspect for particulate matter and discoloration; administer intramuscularly; discard the multiple-dose vial within 28 days after first puncture. [4]
Storage and handling
- BioThrax: store at 2 to 8 °C (36 to 46 °F); do not freeze (discard if frozen); do not use after the expiration date; write the discard date (28 days after the stopper is first pierced) on the vial and carton and keep refrigerated between uses. [3]
- CYFENDUS: store at 2 to 8 °C (36 to 46 °F); protect vials from light; do not shake; do not freeze (discard if frozen); do not use after the expiration date; discard the multiple-dose vial within 28 days after first puncture. [4]
Contraindications and precautions
| Vaccine | Statement |
|---|---|
| BioThrax | Severe allergic reaction (for example anaphylaxis) after a previous dose or a component, including aluminum; the vial stopper contains natural rubber latex and may cause allergic reactions in latex-sensitive individuals. [3] |
| CYFENDUS | Severe allergic reaction (for example anaphylaxis) after a previous dose of Cyfendus, BioThrax or any component; appropriate medical treatment must be available to manage possible anaphylactic reactions. [4] |
Safety and adverse events
BioThrax: the most common (more than 10%) local reactions in clinical studies were tenderness, pain, erythema, edema and arm motion limitation, and the most common (5% or more) systemic reactions were muscle aches, fatigue and headache. [3]
CYFENDUS: the most common (10% or more) injection-site reactions were tenderness (88.1%), pain (86.3%), arm motion limitation (63.7%), warmth (51.2%), induration (37.5%), itching (21.9%), swelling (19.7%) and erythema/redness (17.9%); the most common systemic reactions were muscle aches (75.2%), tiredness (67.1%) and headache (58.0%). [4]
From January 1, 2009 through June 30, 2017 a total of 2,439 AVA-related adverse events were reported to VAERS, 329 (13.5%) of them serious, after approximately 8 million doses administered to approximately 1.9 million DoD service members; VAERS is a spontaneous reporting system and its data generally cannot be used to assess whether a vaccine caused an event. [2]
Special populations
Pregnancy: BioThrax and Cyfendus can cause fetal harm when administered to a pregnant individual; in an observational study there were more birth defects in infants born to individuals vaccinated with BioThrax in the first trimester compared with those vaccinated post-pregnancy or never vaccinated, while data from the BioThrax pregnancy exposure registry do not establish the presence or absence of vaccine-associated risks; the potential benefits of vaccination should be weighed against the potential risk to the fetus. [3] [4]
Lactation and age: it is not known whether Cyfendus is excreted in human milk, and its safety and effectiveness in individuals younger than 18 years have not been established. [4]
Counseling pearls for the pharmacy counter
- Anthrax is not spread from person to person; it spreads through breaks in the skin (cutaneous), by eating infected meat (ingestion), by inhaling spores (inhalation) and by injecting heroin (injection anthrax); all types can cause fever, chills, fatigue and headache and, untreated, severe illness including death. [7]
- Tell the vaccination provider about severe allergies or an allergic reaction after a previous dose, and about pregnancy; the vaccine can cause fetal harm. [3]
- If a severe allergic reaction occurs (hives, swelling of the face and throat, difficulty breathing, a fast heartbeat, dizziness or weakness), call 9-1-1; adverse reactions should be reported to VAERS, and the Countermeasures Injury Compensation Program may help pay for medical care for certain people seriously injured by the vaccine. [7]
Common patient questions
A laboratory worker handles high concentrations of B. anthracis. Which schedule?
The BioThrax label lists an intramuscular primary series at 0, 1 and 6 months with boosters 6 and 12 months after completion and at 12-month intervals thereafter; ACIP (2019) lists a priming series at 0, 1 and 6 months with boosters at 12 and 18 months and annually thereafter. [3] [2]
A first responder wants to maintain protection but is not at high risk. How often is a booster given?
ACIP says a booster dose can be given every 3 years to persons not at high risk who have previously completed the initial priming and booster series and want to maintain protection. [2]
After a suspected aerosol exposure, what is the vaccine schedule?
AVA 0.5 mL subcutaneously at 0, 2 and 4 weeks (or intramuscular in a large-scale emergency), with antimicrobials; Cyfendus is given as two intramuscular 0.5 mL doses two weeks apart with recommended antibacterial drugs. [2] [4]
Can BioThrax be given to a pregnant woman who has been exposed?
The label says it can cause fetal harm and the benefits of vaccination should be weighed against the potential risk to the fetus; the ACIP report says AVA would be made available for pregnant women for post-exposure prophylaxis under appropriate emergency use provisions. [3] [2]
References
- Centers for Disease Control and Prevention. Clinical overview of anthrax. Page dated February 5, 2026. Accessed October 12, 2026. https://www.cdc.gov/anthrax/hcp/clinical-overview/index.html. Accessed October 12, 2026.
- Bower WA, Schiffer J, Atmar RL, et al. Use of anthrax vaccine in the United States: recommendations of the Advisory Committee on Immunization Practices, 2019. MMWR Recomm Rep. 68(4):1-14. (The page header displays the publication date as "July 2, 1950", which appears to be an error; the title and suggested citation give the year as 2019.) Accessed October 12, 2026. https://www.cdc.gov/mmwr/volumes/68/rr/rr6804a1.htm. Accessed October 12, 2026.
- BioThrax (anthrax vaccine adsorbed): prescribing information, revised 11/2025. Emergent BioDefense Operations Lansing LLC. U.S. Food and Drug Administration. Accessed October 12, 2026. https://www.fda.gov/media/71954/download?attachment. Accessed October 12, 2026.
- CYFENDUS (anthrax vaccine adsorbed, adjuvanted): prescribing information, revised 11/2025. Emergent BioDefense Operations Lansing LLC. U.S. Food and Drug Administration. Accessed October 12, 2026. https://www.fda.gov/media/189503/download?attachment. Accessed October 12, 2026.
- U.S. Food and Drug Administration. BioThrax product page (content current as of 07/06/2023). Accessed October 12, 2026. https://www.fda.gov/vaccines-blood-biologics/vaccines/biothrax. Accessed October 12, 2026.
- U.S. Food and Drug Administration. CYFENDUS product page (content current as of 11/06/2025). Accessed October 12, 2026. https://www.fda.gov/vaccines-blood-biologics/vaccines/cyfendus. Accessed October 12, 2026.
- Centers for Disease Control and Prevention. Anthrax vaccine: what you need to know. Vaccine Information Statement, January 8, 2020. Accessed October 12, 2026. https://www.cdc.gov/vaccines/hcp/current-vis/anthrax.html. Accessed October 12, 2026.
For professional education. Check current labeling and guidance before acting. Not medical advice.
