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Introduction Following the withdrawal of Sabin type 2 from trivalent oral poliovirus vaccine (tOPV) in 2016, the introduction of ≥1 dose of inactivated poliovirus vaccine (IPV) in routine immunization was recommended, either as 1 full dose (0.5mL, intramuscular) or 2 fractional doses of IPV (fIPV—0.1mL, intradermal). India opted for fIPV. We conducted a comparative assessment of IPV and fIPV. Methods This was a 4-arm, open-label, multicenter, randomized controlled trial. Infants were enrolled and vaccines administered according to the study design, and the blood was drawn at age 6, 14, and 18 weeks for neutralization testing against all 3 poliovirus types. Results Study enrolled 799 infants. The seroconversion against type 2 poliovirus with 2 fIPV doses was 85.8% (95% confidence interval [CI]: 80.1%-90.0%) when administered at age 6 and 14 weeks, 77.0% (95% CI: 70.5-82.5) when given at age 10 and 14 weeks, compared to 67.9% (95% CI: 60.4-74.6) following 1 full-dose IPV at age 14 weeks. Conclusion The study demonstrated the superiority of 2 fIPV doses over 1 full-dose IPV in India. Doses of fIPV given at 6 and 14 weeks were more immunogenic than those given at 10 and 14 weeks. Clinical Trial Registry of India (CTRI). Clinical trial registration number was CTRI/2017/02/007793. [ABSTRACT FROM AUTHOR]

Background The eradication of wild-type polioviruses in areas with efficient fecal-oral transmission relies on intestinal mucosal immunity induced by oral poliovirus vaccine (OPV). Mucosal immunity is thought to wane over time but the rate of loss of protection has not been examined. Methods We examined the degree and duration of intestinal mucosal immunity in India by measuring the prevalence of vaccine poliovirus in stool samples collected 4–28 days after a “challenge” dose of OPV among 47 574 children with acute flaccid paralysis reported during 2005–2009. Results Previous vaccination with OPV was protective against excretion of vaccine poliovirus after challenge, but the odds of excretion increased significantly with the time since the child was last exposed to an immunization activity (odds ratio, 1.39 [95% confidence interval .99–1.97], 2.04 [1.28–3.25], and 1.31 [1.00–1.70] comparing ≥6 months with 1 month ago for serotypes 1, 2, and 3, respectively). Vaccine administered during the high season for enterovirus infections (April–September) was significantly less likely to result in excretion, especially in northern states (odds ratio, 0.57 [95% confidence interval, .50–.65], 0.58 [.41–.81], and 0.48 [.40–.57] for serotypes 1, 2, and 3). Conclusions Infection with OPV (vaccine “take”) is highly seasonal in India and results in intestinal mucosal immunity that appears to wane significantly within a year of vaccination. [ABSTRACT FROM PUBLISHER]

Background: Despite intensified use of monovalent oral poliovirus type 1 vaccine and improved coverage of immunization campaigns, wild poliovirus type 1 persisted in Indian states of Uttar Pradesh and Bihar during 2006 to 2009.Methods: A serosurvey was conducted among cases of acute flaccid paralysis in the 25 high-polio-incidence districts of western Uttar Pradesh. Children were recruited by age group (6-11 months, 12-24 months, and 25-69 months) from among cases reported through the acute flaccid paralysis surveillance system between November 2008 and August 2009.Results: Seroprevalence for type 1 wild poliovirus was >96.4% for each age group. The seroprevalence of wild poliovirus types 2 and 3 increased with age, from 36.7% to 73.4% for type 2 and from 39.0% to 74.1% for type 3. In addition to the number of type-specific vaccine doses, father's level of education, being from a Muslim family, height for age, and female sex were the socioeconomic risk factors associated with seronegativity to poliovirus.Conclusions: The seroprevalence and risk factors identified in this study were consistent with the epidemiology of polio, and the findings were instrumental in optimizing vaccination strategy in western Uttar Pradesh with respect to the choice of OPV types, the frequency of supplementary immunization campaigns, and the urgency to improve routine immunization services. [ABSTRACT FROM AUTHOR]

Introduction. The objectives of this survey were to assess the seroprevalence of antibodies to poliovirus types 1 and 3 and the impact of bivalent (types 1 and 3) oral poliovirus vaccine (bOPV) use in immunization campaigns in northern India.Methods. In August 2010, a 2-stage stratified cluster sampling method identified infants aged 6–7 months in high-risk blocks for wild poliovirus infection. Vaccination history, weight and length, and serum were collected to test for neutralizing antibodies to poliovirus types 1, 2, and 3.Results. Seroprevalences of antibodies to poliovirus types 1, 2, and 3 were 98% (95% confidence interval [CI], 97%–99%), 66% (95% CI, 62%–69%), and 77% (95% CI, 75%–79%), respectively, among 664 infants from Bihar and 616 infants from Uttar Pradesh. Infants had received a median of 3 bOPV doses and 2 monovalent type 1 OPV (mOPV1) doses through campaigns and 3 trivalent OPV (tOPV) doses through routine immunization. Among subjects with 0 tOPV doses, the seroprevalences of antibodies to type 3 were 50%, 77%, and 82% after 2, 3, and 4 bOPV doses, respectively. In multivariable analysis, malnutrition was associated with a lower seroprevalence of type 3 antibodies.Conclusions. This study confirmed that replacing mOPV1 with bOPV in campaigns was successful in maintaining very high population immunity to type 1 poliovirus and substantially decreasing the immunity gap to type 3 poliovirus. [ABSTRACT FROM PUBLISHER]

Background. Moradabad district in Uttar Pradesh reported the highest number of paralytic polio cases in India during 2001–2007. We conducted a study in Moradabad in 2007 to assess seroprevalence against poliovirus types 1, 2, and 3 in children 6–12 and 36–59 months of age to guide future strategies to interrupt wild poliovirus transmission in high-risk areas.Methods. Children attending 10 health facilities for minor illnesses who met criteria for study inclusion were eligible for enrollment. We recorded vaccination history, weight, and length and tested sera for neutralizing antibodies to poliovirus types 1, 2, and 3.Results. Poliovirus type 1, 2, and 3 seroprevalences were 88% (95% confidence interval [CI], 84%–91%), 70% (95% CI, 66%–75%), and 75% (95% CI, 71%–79%), respectively, among 467 in the younger age group (n = 467), compared with 100% (95% CI, 99%–100%), 97% (95% CI, 95%–98%), and 93% (91%–95%), respectively, among 447 children in the older age group (P < .001 for all serotypes).Conclusions. This seroprevalence study provided extremely useful information that was used by the program in India to guide immunization policies, such as optimizing the use of different OPV formulations in vaccination campaigns and strengthening routine immunization services. Similar surveys in populations at risk should be performed at regular intervals in countries where the risk of persistence or spread of indigenous or imported wild poliovirus is high. [ABSTRACT FROM PUBLISHER]