One Full or Two Fractional Doses of Inactivated Poliovirus Vaccine for Catch-up Vaccination in Older Infants: A Randomized Clinical Trial in Bangladesh

• Published in: The Journal of infectious diseases Vol. 226; no. 8; pp. 1319 - 1326
• Main Authors: Aziz, Asma B, Verma, Harish, Jeyaseelan, Visalakshi, Yunus, Mohammad, Nowrin, Samarea, Moore, Deborah D, Mainou, Bernardo A, Mach, Ondrej, Sutter, Roland W, Zaman, Khalequ
• Format: Journal Article
• Language: English
• Published: United States Oxford University Press 17-10-2022
• Subjects: Aged; Antibodies, Viral; Bangladesh; Humans; Immunization Schedule; Infant; Major; Poliomyelitis - prevention & control; Poliovirus; Poliovirus Vaccine, Inactivated; Poliovirus Vaccine, Oral; Vaccination - methods; Bangladesh; Bangladesh; fractional IPV; inactivated poliovirus vaccine; older cohort; polio
• ISSN: 0022-1899; 1537-6613
• DOI: 10.1093/infdis/jiac205

The polio eradication endgame called for the removal of trivalent oral poliovirus vaccine (OPV) and introduction of bivalent (types 1 and 3) OPV and inactivated poliovirus vaccine (IPV). However, supply shortages have delayed IPV administration to tens of millions of infants, and immunogenicity data are currently lacking to guide catch-up vaccination policies.
We conducted an open-label randomized clinical trial assessing 2 interventions, full or fractional-dose IPV (fIPV, one-fifth of IPV), administered at age 9-13 months with a second dose given 2 months later. Serum was collected at days 0, 60, 67, and 90 to assess seroconversion, priming, and antibody titer. None received IPV or poliovirus type 2-containing vaccines before enrolment.
A single fIPV dose at age 9-13 months yielded 75% (95% confidence interval [CI], 6%-82%) seroconversion against type 2, whereas 2 fIPV doses resulted in 100% seroconversion compared with 94% (95% CI, 89%-97%) after a single full dose (P < .001). Two doses of IPV resulted in 100% seroconversion.
Our study confirmed increased IPV immunogenicity when administered at an older age, likely due to reduced interference from maternally derived antibodies. Either 1 full dose of IPV or 2 doses of fIPV could be used to vaccinate missed cohorts, 2 fIPV doses being antigen sparing and more immunogenic.
NCT03890497.