Community Circulation Patterns of Oral Polio Vaccine Serotypes 1, 2, and 3 After Mexican National Immunization Weeks

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Journal of Infectious Diseases
Volume 209 Issue 11 June 1, 2014
http://jid.oxfordjournals.org/content/current

Community Circulation Patterns of Oral Polio Vaccine Serotypes 1, 2, and 3 After Mexican National Immunization Weeks
Stephanie B. Troy1,a, Leticia Ferreyra-Reyes2,a, ChunHong Huang3, Clea Sarnquist3, Sergio Canizales-Quintero2, Christine Nelson1, Renata Báez-Saldaña2, Marisa Holubar3, Elizabeth erreira-Guerrero2, Lourdes García-García2 and Yvonne A. Maldonado3
Author Affiliations
1Eastern Virginia Medical School, Norfolk, Virginia
2Instituto Nacional de Salud Pública, Cuernavaca, Morelos, México
3Stanford University School of Medicine, Stanford, California
Abstract
Background. With wild poliovirus nearing eradication, preventing circulating vaccine-derived poliovirus (cVDPV) by understanding oral polio vaccine (OPV) community circulation is increasingly important. Mexico, where OPV is given only during biannual national immunization weeks (NIWs) but where children receive inactivated polio vaccine (IPV) as part of their primary regimen, provides a natural setting to study OPV community circulation.
Methods. In total, 216 children and household contacts in Veracruz, Mexico, were enrolled, and monthly stool samples and questionnaires collected for 1 year; 2501 stool samples underwent RNA extraction, reverse transcription, and real-time polymerase chain reaction (PCR) to detect OPV serotypes 1, 2, and 3.
Results. OPV was detected up to 7 months after an NIW, but not at 8 months. In total, 35% of samples collected from children vaccinated the prior month, but only 4% of other samples, contained OPV. Although each serotype was detected in similar proportions among OPV strains shed as a result of direct vaccination, 87% of OPV acquired through community spread was serotype 2 (P < .0001).
Conclusions. Serotype 2 circulates longer and is transmitted more readily than serotypes 1 or 3 after NIWs in a Mexican community primarily vaccinated with IPV. This may be part of the reason why most isolated cVDPV has been serotype 2.