Achieving high immunogenicity against poliovirus with fractional doses of inactivated poliovirus vaccine in Ecuador-results from a cross-sectional serological survey

Gabriel Trueba, Vishali Jeyaseelan, Lazaro Lopez, Bernardo A. Mainou, Yiting Zhang, Alvaro Whittembury, Alfredo Jose Olmedo Valarezo, Gonzalo Baquero, Rosa Romero de Aguinaga, Lucia Jeannete Zurita Salinas, Maria Gabriela Santacruz Mancheno, Diana Elizabeth Medina Chacho, Emmanuelle Quentin, Ana Elena Chevez, Gloria Rey-Benito, Ondrej Mach

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Background: In January 2018, Ecuador changed its routine immunization schedule by replacing one full dose of inactivated poliovirus vaccine (IPV) administered intramuscularly at 2 months of age with two doses of fractional IPV (1/5th of full dose, fIPV) administered intradermally at 2 and 4 months of age; and bivalent oral poliovirus vaccine (serotypes 1 and 3, bOPV) continues to be used. We compared seroprevalence and titres of polio antibodies achieved by the past and the current immunization schedules. Methods: This was a cross-sectional serological survey in children in Ecuador who received bOPV and either one IPV dose in 2017 or two fIPV doses in 2018. One blood sample was collected between October 2020 and March 2021 and analysed for presence of poliovirus neutralizing antibodies at CDC, Atlanta by microneutralization assay. Findings: We obtained 321 analysable samples from 329 (97·6%) enrolled children (160 received IPV and 161 fIPV). For serotype 2, seroprevalence was 50·0% (CI95%= 44·2-55·8%) for IPV and 83·2% (CI95%=78·5-87·1%) for fIPV recipients (p<0·001). Median antibody titers for serotype 2 were significantly lower for IPV than for fIPV recipients (3·0, CI95%= 3 – 3·5 vs. 4·8, CI95%= 4·5 – 5·2, p<0·001). Seroprevalence for serotypes 1 and 3 was above 90% and was not significantly different between IPV and fIPV recipients. Interpretation: Ecuador achieved significantly better poliovirus serotype 2 immunogenicity with two fIPV doses than with one IPV dose, while preserving vaccine supply and reducing costs. Our data provide further evidence that fIPV is a beneficial and potentially a cost-effective option in polio immunization. Funding: WHO obtained funds for the study from Rotary International.

Original languageEnglish
Article number100235
JournalThe Lancet Regional Health - Americas
Volume11
DOIs
StatePublished - Jul 2022
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2022 World Health Organization.

Keywords

  • Ecuador
  • Fractional dose inactivated poliovirus vaccine
  • Poliomyelitis
  • Routine immunization
  • Seroprevalence assay

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