641. Differential Circulation Patterns of Oral Polio Vaccine Serotypes 1, 2, and 3 after Mexican National Immunization Weeks
Session: Oral Abstract Session: Vaccines for all Ages
Friday, October 4, 2013: 9:15 AM
Room: The Moscone Center: 200-212
Background: With prolonged community circulation, oral polio vaccine (OPV) can mutate into circulating vaccine-derived poliovirus (cVDPV), which may cause poliomyelitis outbreaks.  With wild poliovirus nearing eradication, preventing cVDPV by understanding OPV community circulation is increasingly important.  Mexico, where OPV is given to children </=5 years of age only during biannual national immunization weeks (NIWs), provides a natural setting to study OPV community circulation.

Methods: 216 children and household contacts in Veracruz, Mexico, were enrolled, and monthly stool samples and questionnaires collected for one year.  2005 stool samples underwent RNA extraction, reverse transcription, and real time PCR to detect OPV serotypes 1, 2, and 3.

Results: Fifty of 130 (38%) samples collected from subjects who had received OPV within the previous month contained detectable OPV: 8 contained all three serotypes, 15 contained two serotypes, and 27 contained one serotype.  Similar proportions of the 50 positive samples contained each serotype: 22 (44%) vs 29 (58%) vs 30 (60%) samples each for serotypes 1, 2, and 3 respectively.  Of the remaining 1875 samples collected from subjects who had not received OPV within the previous month, 80 (4%) contained detectable OPV, among which 12 represented persistent shedding since the subject received OPV (4 with serotype 2, 6 with serotype 3, and 2 with serotypes 2 and 3).  Of the remaining 68 samples, which were assumed to represent community OPV acquisition and not direct vaccination, 4 contained two serotypes and 64 contained one serotype.  A significantly higher proportion of these 68 positive samples contained serotype 2: 4 (6%) vs 58 (85%) vs 10 (15%) samples each for serotypes 1, 2, and 3 respectively (p<0.0001).  Further, all three serotypes were seen in similar proportions directly after an NIW, but only serotype 2 was detected more than 4 months after an NIW (through 7 months after the NIW).

Conclusion: Although all three OPV serotypes are shed early by vaccinated children in roughly equivalent amounts, serotype 2 circulates longer and at a significantly higher rate than serotypes 1 or 3 in the community.  This may be part of the reason why most isolated cVDPV has been serotype 2.

Stephanie Troy, MD1, Leticia Ferreyra-Reyes, MD2, ChunHong Huang, MS3, Sergio Canizales-Quintero2, Christine Nelson1, Renata Báez-Saldaña, MD2, Elizabeth Ferreira-Guerrero, MD2, Lourdes García-García, MD2 and Yvonne Maldonado, MD, FIDSA4, (1)Eastern Virginia Medical School, Norfolk, VA, (2)Instituto Nacional De Salud Pública, Cuernavaca, Mexico, (3)Stanford University School of Medicine, Stanford, CA, (4)Pediatrics, Stanford University School of Medicine, Stanford, CA


S. Troy, None

L. Ferreyra-Reyes, None

C. Huang, None

S. Canizales-Quintero, None

C. Nelson, None

R. Báez-Saldaña, None

E. Ferreira-Guerrero, None

L. García-García, None

Y. Maldonado, None

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