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Poliovirus (inactivated) type 2 (MEF-1 strain) is an inactivated poliovirus component used in vaccines. It is one of three poliovirus strains — Type 1 (Mahoney), Type 2 (MEF-1), and Type 3 (Saukett) — that together form inactivated poliovirus vaccines (IPV).[5] The substance appears in the EU Clinical Trials Information System as part of fixed-dose combination products, including Tetravac, REPEVAX, and Hexyon.[3][1][2] It is authorised as a medicine in Finland, Poland, and the European Union, with Sanofi Pasteur Europe as the authorisation holder.
The MEF-1 strain is grown in vero cells, a continuous line of monkey kidney cells cultivated on microcarriers.[5] After growth, the virus is inactivated so it cannot cause disease, then purified and concentrated. When injected, the inactivated virus prompts the immune system to produce antibodies against poliovirus type 2 without causing infection. This protection is part of the broader immune response generated by combination vaccines that contain this component.
The substance is formulated as a suspension for injection and is given by intramuscular or intramuscular injection routes.[3][1][2] In the trials, the combination vaccines containing this component are administered as 0.5 ml injections. A paediatric formulation exists in at least one product record.
Four clinical trials in the registry involve this substance. Two are completed and two are authorised. The trials span Phase 2 and Phase 3.
The completed Phase 3 trial (2024-510787-23-00) enrolled 138 participants and investigated maternal pertussis immunization in Finland, measuring PT-specific IgG antibody geometric mean concentration in children at 4 years plus 28 days.[3] The second completed trial (2023-508416-35-00) enrolled 99 healthy adults and examined whether booster vaccination with Tdap-IPV reduces Bordetella pertussis colonisation after intranasal challenge.[1]
The authorised Phase 2 trial (2023-510465-10-00) enrolled 750 children, toddlers, and infants to describe the safety and immune response of MenPenta vaccine formulations, with the substance appearing as a comparator or auxiliary vaccine.[2] The authorised Phase 2 trial (NCT06989359) enrolled 45 participants and evaluates the safety and tolerability of ADX-038 in complement-mediated kidney disease, with the substance as an auxiliary vaccine.[4]
Primary outcomes across the trials include antibody geometric mean concentrations, colonisation rates, adverse events, and serum bactericidal antibody titres.
The IPOL label describes the vaccine as a sterile suspension of three inactivated poliovirus types, produced with enhanced potency.[5] The label does not provide a detailed side-effect profile in the supplied excerpt, so specific adverse events for this component are not listed here.
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