{"id":1049,"date":"2026-03-05T10:08:47","date_gmt":"2026-03-05T10:08:47","guid":{"rendered":"https:\/\/www.merckvaccines.com\/enflonsia\/?page_id=1049"},"modified":"2026-03-23T08:59:46","modified_gmt":"2026-03-23T08:59:46","slug":"frequently-asked-questions","status":"publish","type":"page","link":"https:\/\/www.merckvaccines.com\/enflonsia\/frequently-asked-questions\/","title":{"rendered":"FAQ"},"content":{"rendered":"\n\n
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Frequently asked questions for ENFLONSIATM<\/sup> (clesrovimab-cfor)<\/strong><\/strong><\/strong><\/mark><\/h1>

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FAQs for ENFLONSIA<\/h2><\/div>\n\n\n\n
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What is the indication and usage for ENFLONSIA?<\/h3><\/summary>
ENFLONSIA is indicated for the prevention of respiratory syncytial virus (RSV) lower respiratory tract disease in neonates and infants who are born during or entering their first RSV season.<\/span><\/div><\/details><\/div>\n\n\n\n
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What is the Selected Safety Information for ENFLONSIA?<\/h3><\/summary>
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Do not administer ENFLONSIA to infants with a history of serious hypersensitivity reactions, including anaphylaxis, to any component of ENFLONSIA.<\/p>\n\n\n\n

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Serious hypersensitivity reactions, including anaphylaxis, have been observed with other human immunoglobulin G1 (IgG1) monoclonal antibodies. If signs or symptoms of a clinically significant hypersensitivity reaction or anaphylaxis occur, initiate appropriate medications and\/or supportive therapy.<\/p>\n\n\n\n

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ENFLONSIA may interfere with some immunologically-based RSV diagnostic assays (i.e., rapid antigen tests) as observed in laboratory studies. Confirmation using a reverse transcriptase polymerase chain reaction (RT-PCR) assay is recommended when rapid antigen assay results are negative and clinical observations are consistent with RSV infection.<\/p>\n\n\n\n

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The most common adverse reactions were injection-site erythema (3.8%), injection-site swelling (2.7%), and rash (2.3%).<\/p>\n<\/div><\/details><\/div>\n\n\n\n

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What is the dosing for ENFLONSIA?<\/h3><\/summary>
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The recommended dose is 105 mg administered as a single intramuscular (IM) injection.<\/p>\n\n\n\n

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For neonates and infants born during the RSV season, administer ENFLONSIA once starting from birth. For infants born outside the RSV season, administer ENFLONSIA once prior to the start of their first RSV season considering 5 months duration of protection by ENFLONSIA.<\/p>\n\n\n\n

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For infants undergoing cardiac surgery with cardiopulmonary bypass during or entering their first RSV season, an additional 105 mg dose is recommended as soon as the infant is stable after surgery to ensure adequate clesrovimab-cfor serum levels.<\/p>\n<\/div><\/details><\/div>\n\n\n\n

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What are the contraindications of ENFLONSIA?<\/h3><\/summary>
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ENFLONSIA is contraindicated in infants with a history of serious hypersensitivity reactions, including anaphylaxis, to any component of ENFLONSIA.<\/p>\n<\/div><\/details><\/div>\n\n\n\n

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What are the warnings and precautions associated with ENFLONSIA?<\/h3><\/summary>
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Hypersensitivity Including Anaphylaxis – Serious hypersensitivity reactions, including anaphylaxis, have been observed with other human immunoglobulin G1 (IgG1) monoclonal antibodies. If signs or symptoms of a clinically significant hypersensitivity reaction or anaphylaxis occur, initiate appropriate medications and\/or supportive therapy.<\/p>\n\n\n\n

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RSV Diagnostic Test Interference – Clesrovimab-cfor may interfere with some immunologically-based RSV diagnostic assays (i.e., rapid antigen tests) as observed in laboratory studies. Confirmation using a reverse transcriptase polymerase chain reaction (RT-PCR) assay is recommended when rapid antigen assay results are negative and clinical observations are consistent with RSV infection.<\/p>\n<\/div><\/details><\/div>\n\n\n\n

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What are the most common adverse reactions of ENFLONSIA?<\/h3><\/summary>
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The most common adverse reactions were injection-site erythema (3.8%), injection-site swelling (2.7%) and rash (2.3%).<\/p>\n<\/div><\/details><\/div>\n\n\n\n

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How do I order ENFLONSIA for the upcoming RSV season?<\/h3><\/summary>
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ENFLONSIA is available for ordering as a single dose syringe option, as well as a 10-pack syringe option.<\/p>\n\n\n\n

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You can order ENFLONSIATM<\/sup> (clesrovimab-cfor) directly from Merck and through Merck Authorized Distributors.<\/p>\n<\/div><\/details><\/div>\n\n\n\n

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Does ENFLONSIA come with pre-filled syringe(s)?<\/h3><\/summary>
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Yes. ENFLONSIA is available as a single dose, pre-filled syringe package or 10-pack pre-filled syringe option.<\/p>\n<\/div><\/details><\/div>\n\n\n\n

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Is ENFLONSIA included in the Vaccines for Children (VFC) Program?<\/h3><\/summary>
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Yes, ENFLONSIA is available via the Vaccines for Children (VFC) Program. Check with local program managers on state availability.<\/p>\n<\/div><\/details><\/div>\n\n\n\n

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When should an infant receive ENFLONSIA?<\/h3><\/summary>
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For neonates and infants born during the RSV season, they should receive the recommended dose of 105 mg starting from birth. For infants born outside the RSV season, administer ENFLONSIA once prior to the start of their first RSV season considering 5 months duration of protection by ENFLONSIA.<\/p>\n\n\n\n

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For infants undergoing cardiac surgery with cardiopulmonary bypass during or entering their first RSV season, an additional 105 mg dose is recommended as soon as the infant is stable after surgery to ensure adequate clesrovimab-cfor serum levels.<\/p>\n<\/div><\/details><\/div>\n\n\n\n

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Can ENFLONSIA be co-administered with other pediatric vaccines?<\/h3><\/summary>
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ENFLONSIA can be given concomitantly with childhood vaccines. When ENFLONSIA is administered concomitantly with injectable vaccines, it should be given using a separate syringe and at a different injection site. Do not mix ENFLONSIA with any vaccines or medications in the same syringe or vial.<\/p>\n\n\n\n

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There is no information regarding co-administration of ENFLONSIA with other immunoglobulin products. There are no data regarding substitution of ENFLONSIA for palivizumab once prophylaxis treatment is initiated with palivizumab for the RSV season.<\/p>\n<\/div><\/details><\/div>\n\n\n\n

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What is the CPT code for ENFLONSIA?<\/h3><\/summary>
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The CPT code for ENFLONSIA is 90382.1<\/sup><\/p>\n\n\n\n

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CPT, Current Procedural Terminology. <\/p>\n\n\n\n

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CPT is a registered trademark of the American Medical Association.<\/p>\n<\/div><\/details><\/div>\n\n\n\n

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What is the CVX code for ENFLONSIA?<\/h3><\/summary>
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The CVX code for ENFLONSIA is 332.1<\/sup><\/p>\n<\/div><\/details><\/div>\n\n\n\n

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What are the NDC codes for ENFLONSIA?<\/h3><\/summary>
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The NDC codes for ENFLONSIA are as follows:<\/p>\n\n\n\n

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105 mg\/0.7 mL single-dose Carton of 1:<\/p>\n\n\n\n

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– 10-Digit: 0006-5073-01<\/p>\n\n\n\n

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– 11-Digit: 00006-5073-01<\/p>\n\n\n\n

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105 mg\/0.7 mL single-dose Carton of 10:<\/p>\n\n\n\n

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– 10-Digit: 0006-5073-02<\/p>\n\n\n\n

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– 11-Digit: 00006-5073-02<\/p>\n\n\n\n

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NDC, National Drug Code<\/p>\n<\/div><\/details><\/div>\n\n\n\n

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Reference:<\/strong><\/h2><\/div>\n\n\n\n\n
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    \n
  1. Immunization Information Systems (IIS): CPT codes mapped to CVX codes. Centers for Disease Control and Prevention. Last reviewed November 26, 2025. Accessed January 6, 2026. https:\/\/www2a.cdc.gov\/vaccines\/iis\/iisstandards\/vaccines.asp?rpt=cpt<\/span><\/li>\n<\/ol>\n<\/div>\n\n\n\n\n
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