Immunogenicity of Monovalent Type 2 Oral Poliovirus Vaccine
Condition: Poliomyelitis
MeSH terms: Poliomyelitis
Study type: Interventional
Phase: Phase 4

Summary: 
      This is an open-label phase IV, randomized controlled trial of mOPV2 alone and mOPV2 along
      with IPV. This trial will assess the impact on type 2 immunogenicity by reducing the interval
      between mOPV2 doses. The trial will also evaluate any difference in immunogenicity when the
      first dose of mOPV2, in a two dose schedule with a four week interval, is administered
      simultaneously with IPV.
    

Detailed description: 
      The Strategic Advisory Group of Experts on Immunization (SAGE) has recommended a phased
      cessation of OPVs starting with serotype 2 (OPV2). This is because the last case of type 2
      wild poliovirus (WPV2) was reported in 1999 and type 2 vaccine poliovirus is associated with
      the highest risk of causing paralysis due to reversion to vaccine derived poliovirus (VDPV),
      in which the reverted virus acquires not only the ability to cause paralysis but also the
      ability to transmit from person-to-person. Withdrawal of OPV2 will be done through the
      replacement worldwide of trivalent OPV (tOPV) with bivalent (types 1 and 3) OPV (bOPV) for
      use in routine immunization and in campaigns.

      After the tOPV to bOPV switch, there will be strict biosafety requirements for the use of
      vaccines containing OPV2. Trivalent OPV will no longer exist and use of monovalent OPV2
      (mOPV2) will be limited to responding to a type 2 outbreak. To respond to poliovirus type 2
      outbreaks, the Global Polio Eradication Initiative has proposed delivering using mOPV2 in
      campaigns conducted in the primary zone of the outbreak and IPV in campaigns conducted in
      areas adjacent to outbreak zone. Therefore, mOPV2 will be a critical component of response to
      poliovirus type 2 outbreaks.

      Typically, polio campaigns are conducted at an interval of 4 weeks. Recently, a clinical
      trial conducted by icddr,b and the U.S. Centers for Disease Control and Prevention (CDC) in
      Matlab and Mirpur in Bangladesh demonstrated non-inferiority of type 1 seroconversion after
      bOPV or mOPV1 at a 2 week interval compared to 4 weeks between doses. Based these findings,
      the Global Polio Eradication Initiative (GPEI) concluded that the immune response to "OPV is
      satisfactory when the interval between doses is shortened to 14 or even 7 days (in case of
      mOPV1)" and has used short-interval campaigns to deliver mOPV1 and bOPV in areas with
      security-limited access and for outbreak response. However, there are no data and no current
      or planned polio clinical trials are assessing the impact on immunogenicity of mOPV2 of a
      reduction in the interval between mOPV2 doses or of administration of mOPV2 in combination
      with IPV. Therefore, the findings from the trial proposed in this protocol have a direct and
      immediate implication on strategies to respond to type 2 polio outbreaks.

      Field site: The study will be carried out in urban slums in Mirpur and Mohakahli in Dhaka.
    

Intervention name(s): mOPV2 at 6 and 7 weeks of age; mOPV2 at 6 and 8 weeks of age; mOPV2 at 6 and 10 weeks of age; IPV at 6 weeks of age
Intervention type(s): Biological; Biological; Biological; Biological
Intervention description(s): Participants assigned to this intervention will receive a dose of monovalent oral type 2 polio vaccine (mOPV2) at 6 and 7 weeks of age; Participants assigned to this intervention will receive a dose of monovalent oral type 2 polio vaccine (mOPV2) at 6 and 8 weeks of age; Participants assigned to this intervention will receive a dose of monovalent oral type 2 polio vaccine (mOPV2) at 6 and 10 weeks of age; Participants assigned to this intervention will receive a dose of inactivated polio vaccine (IPV) 6 weeks of age
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Prevention
Keywords: Polio; Inactivated polio vaccine; oral polio vaccine; monovalent type 2 oral polio vaccine