845. Preventing Polio Post-eradication: Elucidating Polio Virus Shedding and Transmission Patterns in the Presence of IPV and OPV
Session: Oral Abstract Session: Global Diseases at Home and Abroad
Thursday, October 27, 2016: 2:15 PM
Room: 288-290

Background: As wild poliovirus is eradicated and countries switch from Oral Polio Vaccine (OPV) to Inactivated Polio Vaccine (IPV) per the WHO recommendations, preventing polio disease from circulating vaccine-derived poliovirus (VDPV) is a top priority. Mexico provides a natural environment to study poliovirus shedding and transmission patterns as it provides routine IPV immunization and twice annual OPV campaigns

                                                                                                             

Methods: We enrolled 450 households with children eligible for OPV before the February 2015 national immunization week (NIW); 150 households from three distinct communities near Orizaba, Mexico.  In each community, a different proportion of eligible children received OPV (10%, 30%, and 70%). Transmission was measured by RT-PCR detection of OPV in stool samples collected serially from vaccinated children, their household contacts, and other families in the community (Figure 1)

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Figure 1: Stool sample collection schema

Results: A total of 1,828 individuals from 450 households were enrolled; 7,833 stool samples have been analyzed to date, and 344 (4.4%) have been OPV positive. Most analyzed samples are from two of the communities through day 14 post-vaccination; therefore only those results are shown

Figure 2 shows shedding patterns from baseline to day 14 in the 10% and 70% vaccinated communities. A total of 176 individuals (9.6%) shed OPV, 80 of whom were not vaccinated. There was a significant difference in shedding proportion among non-vaccinees based on community OPV coverage:  7% versus 2% of non-vaccinees shed in the 70% versus 10% OPV vaccinated communities (p<.0001, chi square); no significant difference in shedding rates was found comparing vaccinated individuals in those two communities.  Among non-vaccinees, there was no difference in shedding based on age (<5, 5-18, >18 years)

Figure 2: Shedding patterns

Red: 70% OPV Community

Blue: 10% OPV Community

Conclusion: These results demonstrate a significant increase in shedding and community transmission of OPV related to increased levels of OPV vaccinated individuals, however community transmission was not age-related.  Further analysis of factors associated with persistence of OPV shedding and transmission are underway

Clea C. Sarnquist, DrPH, MPH1, Lourdes Garcia-Gacia, MD2, Leticia Ferreyra Reyes, MD2, Rogelio Montero-Campos, MS2, Luis Pablo Cruz-Hervert, MSc2, Jonathan Altamirano, MS1, Marisa Holubar, MD, MS3, Aisha Talib, MPP1, Natasha Purington, MS1, Meira Halpern, PhD1, Elizabeth Ferreira, MD2, Guadalupe Delgado, MPH2, Sergio Canizales Quintero, BA2 and Yvonne Maldonado, MD, FIDSA, FPIDS1, (1)Pediatrics, Stanford University School of Medicine, Stanford, CA, (2)Instituto Nacional de Salud P├║blica, Cuernavaca, Mexico, (3)Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA

Disclosures:

C. C. Sarnquist, None

L. Garcia-Gacia, None

L. Ferreyra Reyes, None

R. Montero-Campos, None

L. P. Cruz-Hervert, None

J. Altamirano, None

M. Holubar, None

A. Talib, None

N. Purington, None

M. Halpern, None

E. Ferreira, None

G. Delgado, None

S. Canizales Quintero, None

Y. Maldonado, None

Findings in the abstracts are embargoed until 12:01 a.m. CDT, Wednesday Oct. 26th with the exception of research findings presented at the IDWeek press conferences.