Krystexxa®?

Krystexxa® (generic name tixagevimab/cilgavimab) is a combination of two monoclonal antibodies that target the spike protein of SARS‑CoV‑2, the virus that causes COVID‑19.

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What is Krystexxa® used for?

1. Pre‑exposure prophylaxis (PrEP)

   • For adults and children 12 years and older who have not yet been vaccinated or who cannot mount an adequate immune response to vaccination (e.g., immunocompromised individuals).
   • Administered as a single intramuscular (IM) injection (usually 300 mg of each antibody, 600 mg total) or a 150 mg/150 mg dose for certain indications.

2. Post‑exposure prophylaxis

   • For individuals who have had close contact with a confirmed COVID‑19 case and are at high risk of severe disease (e.g., immunocompromised).
   • Dose and timing are similar to PrEP.

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How does it work?

• The two antibodies, tixagevimab and cilgavimab, bind to distinct, non‑overlapping sites on the viral spike protein, neutralizing the virus and preventing it from entering human cells.
• They have been engineered to reduce the risk of viral escape and to provide a long‑lasting protective effect (typically several months).

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Dosage & Administration

Indication	Dose	Administration	Frequency
PrEP (unvaccinated or immunocompromised)	300 mg tixagevimab + 300 mg cilgavimab (600 mg total)	Single IM injection (deltoid or gluteal)	One‑time, can be repeated if indicated (e.g., after 6 months)
Post‑exposure	Same as PrEP	Same	One‑time

• The injection can be given at home or in a healthcare setting; trained staff may administer it.

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Who can receive Krystexxa®?

• Adults and adolescents ≥12 years weighing ≥40 kg (or ≥12 kg for the 150 mg/150 mg dose).
• Immunocompromised patients, such as those with B‑cell disorders, on B‑cell‑depleting therapies, or undergoing transplant.
• Vaccinated individuals can receive Krystexxa® if they are at high risk of severe disease and have a poor antibody response.

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Contraindications

• Known hypersensitivity to any component of the product.
• No contraindication based on pregnancy or breastfeeding, but data are limited; discuss with a healthcare provider.

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Common Adverse Reactions

Symptom	Frequency (in clinical studies)
Injection‑site pain, redness, swelling	~10‑20 %
Headache	<5 %
Fatigue	<5 %
Nausea, vomiting	<5 %
Rare allergic reactions (anaphylaxis)	<1 %

Most reactions are mild and resolve within a few days. If you develop a severe allergic reaction (difficulty breathing, swelling of the face/neck), seek emergency care immediately.

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Important Safety Information

• Drug Interactions: No known clinically significant interactions. However, other monoclonal antibodies or immunotherapies may affect overall immune status.
• Vaccines: It can interfere with the immune response to other vaccines; wait at least 1–2 months after Krystexxa® before receiving vaccines that require a robust antibody response.
• Pregnancy & Lactation: Limited data; use only if benefits outweigh risks. Discuss with your provider.

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Storage & Handling

• Store at 2–8 °C (refrigerated); do not freeze.
• Reconstitute with the supplied diluent immediately before use.
• Use within the manufacturer’s recommended window after reconstitution (typically 24–48 h).

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How does Krystexxa® compare to other COVID‑19 prophylactics?

• Monoclonal antibody combinations (e.g., tixagevimab/cilgavimab) target the virus directly and are effective even in people who cannot mount a vaccine response.
• Vaccines (mRNA, viral vector, inactivated) induce an endogenous immune response and are the first line of defense for most people.
• Antiviral pills (e.g., Paxlovid) are used for treatment after infection, not for prevention.

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What to do if you receive Krystexxa®?

1. Observe the injection site for pain, redness, or swelling. Apply a cool compress if needed.
2. Report any symptoms such as fever, rash, shortness of breath, or anaphylaxis to your healthcare provider or call 911.
3. Follow up with your clinician to discuss any ongoing risk of COVID‑19 exposure and whether repeat dosing is needed.

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Bottom line

Krystexxa® is a powerful, antibody‑based prophylactic for individuals who are at high risk for severe COVID‑19 and have a weak or absent vaccine‑induced immune response. It is administered as a single intramuscular injection and provides protection for several months. Always discuss with a qualified healthcare professional to determine if it’s the right option for your situation.