Mresvia (Single-Stranded 5' Capped Mrna Encoding The Respiratory Syncytial Virus Glycoprotein F Stabilized In)

Mresvia is an mRNA vaccine that targets the respiratory syncytial virus (RSV) to prevent infection.

• Prevention of RSV infection: Provides immunity against respiratory syncytial virus in infants, older adults, and other at‑risk populations.
• Seasonal prophylaxis: Reduces incidence of RSV‑related lower respiratory tract disease during the RSV season.
• Hospitalized patients at risk: Helps lower RSV‑related complications in high‑risk hospitalized individuals.

• Mresvia delivers single‑stranded, 5′‑capped messenger RNA encoding the RSV F glycoprotein into host muscle cells after intramuscular injection. The mRNA is translated by cellular ribosomes, producing the F protein antigen in situ. This antigen is presented to the immune system, stimulating both B‑cell–mediated antibody production and T‑cell responses, thereby establishing protective immunity against subsequent RSV exposure.

Mresvia, like other vaccines, may be associated with local and systemic reactions.

Common Side Effects

• Injection site pain: Mild to moderate discomfort at the injection site.
• Redness or swelling: Localized erythema or edema that resolves within a few days.
• Fever: Transient low‑grade fever occurring within 24‑48 hours.
• Headache or fatigue: Generalised tiredness or mild headache post‑vaccination.

Serious or Rare Side Effects

• Anaphylaxis: Severe allergic reaction requiring immediate medical attention.
• Guillain‑Barré syndrome: Rare neurological disorder presenting with muscle weakness.
• Myocarditis or pericarditis: Inflammation of heart muscle or surrounding tissue.
• Thrombocytopenia: Low platelet count that may cause abnormal bleeding.
• Seizures: Uncommon neurologic event, especially in febrile infants.

Before administering Mresvia, certain precautions should be observed.

• Screen for severe allergic reactions: Avoid administration in individuals with known hypersensitivity to any vaccine component.
• Observe after injection: Monitor for at least 15 minutes for immediate reactions.
• Pregnancy considerations: Use only if the expected benefit outweighs potential risk; consult a healthcare provider.
• Immunocompromised patients: May have reduced response; evaluate risk‑benefit carefully.
• Concurrent vaccines: May be given with other vaccines at different anatomical sites.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze or shake.

Mresvia may interact with certain medical products or conditions.

Major Interactions (Avoid)

• Live attenuated vaccines: Concomitant use may interfere with immune response; avoid simultaneous administration.
• Immunosuppressive therapy: May diminish vaccine efficacy; avoid if possible during active immunosuppression.
• Severe allergic reaction to a previous dose: Contraindicated.

Moderate Interactions (Monitor Closely)

• Antipyretics (acetaminophen, ibuprofen): May mask fever; use as needed.
• Other injectable vaccines: May increase local reactogenicity; separate injection sites.
• Blood products within 4 weeks: Could affect immune response; monitor patient closely.