Cyfendus (anthrax vaccine adsorbed, adjuvanted) is a vaccine indicated for the post-exposure prophylaxis of anthrax disease following suspected or confirmed exposure to Bacillus anthracis in persons aged 18 through 65 years of age. It is administered in conjunction with recommended antibacterial drugs.

Anthrax is an infection caused by the Gram-positive, spore-forming bacteria called Bacillus anthracis, which occurs naturally in soil and commonly affects domestic and wild animals when they breathe in or ingest spores in contaminated soil, plants, or water. Humans can contract anthrax if they come in contact with infected animals or contaminated animal products.

The first anthrax vaccine was developed in the 1970s and vaccination of U.S. military personnel began in the 1990s due to increased concern about the use of anthrax as a biological weapon. Vaccination was also offered in 2001 to civilians who had been exposed to anthrax after intentional mailings of anthrax spores. Cyfendus is Emergent’s follow-up to its previous anthrax vaccine, BioThrax.

Cyfendus works by inducing antibodies against B. anthracis that may help protect the vaccinated person by neutralizing the cytotoxic and lethal toxins produced by the bacteria. It contains anthrax vaccine adsorbed (AVA) plus an additional adjuvant which elicits a rapid immune response so that two doses administered over 14 days provides adequate protection.

Cyfendus was FDA-approved on July 20, 2023.

Cyfendus may cause an allergic reaction, including anaphylaxis. Appropriate medical treatment must be available to manage possible anaphylactic reactions following administration.

Can cause fetal harm when administered during pregnancy. An observational study reported more birth defects in infants born to individuals vaccinated with BioThrax (an anthrax vaccine with the same active ingredient) in the first trimester compared to those born to individuals who had not yet been vaccinated. 

Cyfendus may not protect all vaccine recipients from anthrax disease.

The effectiveness of Cyfendus has only been studied in animals, it has not been studied in humans because there are not enough people who get the disease naturally, and it is not ethical to expose people to anthrax on purpose to find out how well the vaccine works.

The safety of Cyfenus has not been studied in children or young adults under the age of 18 years or in adults older than 65 years.

Cyfendus is given as an 0.5mL injection in your muscle, usually the deltoid muscle of your arm, by a healthcare provider. The second dose is administered two weeks later.

After getting the first dose, it is important to come back for the second dose two weeks later, otherwise, you will not be fully protected.

Cyfendus is given because you may have been exposed to anthrax. It is important that you also take antibacterial drugs as recommended by your healthcare provider.

Do not receive Cyfendus if you have a history of severe allergic reaction to any ingredient of the vaccine, including aluminum hydroxide, benzethonium chloride, formaldehyde, or CPG 7909, or have experienced a serious reaction with a prior Cyfendus or BioThrax vaccine.

To make sure Cyfendus is safe for you, tell your doctor if you:

• have immune problems, or take steroid or cancer treatments
• take any medications, including over-the-counter medicines and supplements
• are pregnant, could be pregnant, plan to get pregnant soon, or are nursing a baby.

Pregnancy

Cyfendus can cause fetal harm, including birth defects when administered during pregnancy. If you discover you were pregnant at the time you received Cyfendus, tell your healthcare provider right away.

Breastfeeding

It is not known if Cyfendus is excreted in human milk. Consider the developmental and health benefits of breastfeeding along with the mother's clinical need and any potential adverse effects on the breastfed child, or from the underlying maternal condition.

The most common side effects of Cyfendus are:

• pain/tenderness, warmth, hardness, itching, swelling, redness, and bruising at the injection site
• problems moving the arm in which you received the vaccine
• muscle aches
• tiredness
• headache
• fever.

These are not all the possible side effects of Cyfendus. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088. You may also report side effects directly to www.vaers.hhs.gov or Emergent BioSolutions at 1-800-768-2304 or [email protected].

Storage

Store at 2°C to 8°C (36°F to 46°F). Protect vials from light. Do not freeze. Discard if the product has been frozen.

To avoid foaming, DO NOT shake.

Do not use after the expiration date printed on the label.

The vial stoppers are not made with natural rubber latex.