Showing papers by "Harish Verma published in 2016"

Fractional-Dose Inactivated Poliovirus Vaccine Immunization Campaign - Telangana State, India, June 2016.

Abstract: Wild poliovirus type 2 was declared eradicated in September 2015 (1). In April 2016, India, switched from use of trivalent oral poliovirus vaccine (tOPV; containing types 1, 2, and 3 polio vaccine viruses), to bivalent OPV (bOPV; containing types 1 and 3), as part of a globally synchronized initiative to withdraw Sabin poliovirus type 2 vaccine. Concurrently, inactivated poliovirus vaccine (IPV) was introduced into India's routine immunization program to maintain an immunity base that would mitigate the number of paralytic cases in the event of epidemic transmission of poliovirus type 2 (2,3). After cessation of use of type 2 Sabin vaccine, any reported isolation of vaccine-derived poliovirus type 2 (VDPV2) would be treated as a public health emergency and might need outbreak response with monovalent type 2 oral vaccine, IPV, or both (4). In response to identification of a VDPV2 isolate from a sewage sample collected in the southern state of Telangana in May 2016, India conducted a mass vaccination campaign in June 2016 using an intradermal fractional dose (0.1 ml) of IPV (fIPV). Because of a global IPV supply shortage, fIPV, which uses one fifth of regular intramuscular (IM) dose administered intradermally, has been recommended as a response strategy for VDPV2 (5). Clinical trials have demonstrated that fIPV is highly immunogenic (6,7). During the 6-day campaign, 311,064 children aged 6 weeks-3 years were vaccinated, achieving an estimated coverage of 94%. With appropriate preparation, an emergency fIPV response can be promptly and successfully implemented. Lessons learned from this campaign can be applied to successful implementation of future outbreak responses using fIPV.

Human Circulating Antibody-Producing B Cell as a Predictive Measure of Mucosal Immunity to Poliovirus

Abstract: Background The “gold standard” for assessing mucosal immunity after vaccination with poliovirus vaccines consists in measuring virus excretion in stool after challenge with oral poliovirus vaccine (OPV). This testing is time and resource intensive, and development of alternative methods is a priority for accelerating polio eradication. We therefore evaluated circulating antibody-secreting cells (ASCs) as a potential means to evaluate mucosal immunity to poliovirus vaccine. Methods 199 subjects, aged 10 years, and previously immunized repeatedly with OPV, were selected. Subjects were assigned to receive either a booster dose of inactivated poliovirus vaccine (IPV), bivalent OPV (bOPV), or no vaccine. Using a micro-modified whole blood-based ELISPOT assay designed for field setting, circulating poliovirus type-specific IgA- and IgG-ASCs, including gut homing α4β7+ ASCs, were enumerated on days 0 and 7 after booster immunization. In addition, serum samples collected on days 0, 28 and 56 were tested for neutralizing antibody titers against poliovirus types 1, 2, and 3. Stool specimens were collected on day 28 (day of bOPV challenge), and on days 31, 35 and 42 and processed for poliovirus isolation. Results An IPV dose elicited blood IgA- and IgG-ASC responses in 84.8 to 94.9% of subjects, respectively. In comparison, a bOPV dose evoked corresponding blood ASC responses in 20.0 to 48.6% of subjects. A significant association was found between IgA- and IgG-ASC responses and serum neutralizing antibody titers for poliovirus type 1, 2, 3 (p<0.001). In the IPV group, α4β7+ ASCs accounted for a substantial proportion of IgA-ASCs and the proportion of subjects with a positive α4β7+ IgA-ASC response to poliovirus types 1, 2 and 3 was 62.7%, 89.8% and 45.8%, respectively. A significant association was observed between virus excretion and α4β7+ IgA- and/or IgG-ASC responses to poliovirus type 3 among immunized children; however, only a weak association was found for type 1 poliovirus. Discussion Our results suggest that virus-specific blood ASCs, especially for type 3 poliovirus, can serve as surrogate of mucosal immunity after vaccination. Further studies are needed to evaluate the duration of such memory responses and to assess the programmatic utility of this whole blood-based mucosal ASC testing for the polio eradication program.

Role of Serial Polio Seroprevalence Studies in Guiding Implementation of the Polio Eradication Initiative in Kano, Nigeria: 2011–2014

Abstract: In 1988, the World Health Assembly resolved to eradicate poliomyelitis by 2000 [1]. Subsequently, the Global Polio Eradication Initiative (GPEI) was able to reduce the number of polio-endemic countries and wild poliovirus (WPV) cases from 125 and 350 000, respectively, in 1988 to 3 and 416, respectively, by 2013 [2]. Indigenous transmission of WPV types 2 and 3 (WPV2 and WPV3) has since been interrupted globally [3, 4]. Nigeria was one of 3 remaining polio-endemic countries in the world, alongside Afghanistan and Pakistan [5], but on 25 September 2015, following the historical interruption of transmission of WPV for 14 months, the World Health Organization (WHO) director general, Dr Margaret Chan, on behalf of the WHO, delisted Nigeria as a polio-endemic country after 17 years of the country's polio eradication effort. However, until 2012, Nigeria was the only country with transmission of all 3 poliovirus serotypes: WPV1, WPV3, and circulating vaccine-derived poliovirus type 2 (cVDPV2) [6], despite the conduct of multiple supplementary immunization activities (SIAs) and the use of more-immunogenic polio vaccines [7]. This indicated a substantial immunity gap, which led the country to determine how well children were protected against polio and where the remaining gaps driving persistent transmission were. Based on the recommendations in the GPEI 2010–2012 strategic plan [8] on the conduct of polio seroprevalence surveys (SPS), the Nigerian government, with GPEI partners, decided to implement polio SPS in the high-risk states of the country. The objective was to estimate the level of population immunity, measure the programmatic progress through repeat surveys, and provide valuable insight for development of innovative strategies to interrupt poliovirus transmission. Kano State has long been considered the epicenter of polio transmission in Nigeria and as one of the world's poliovirus sanctuaries [9, 10]. The state continues to be at high risk, such that even with substantial reduction in the recorded number of polio cases in Nigeria in 2014, it accounted for 5 of 6 WPV1 cases and 10 of 30 cVDPV2 cases in the country. By the recent joint WHO, Centers for Disease Control and Prevention (CDC), and Global Goods classification, 20 of the 38 local government areas (LGAs; 53%) at very high-risk (VHR) for polio transmission are from Kano State. All 8 urban LGAs of Kano Metropolitan Area (KMA)—Kano Municipal, Fagge, Nassarawa, Dala, Gwale, Tarauni, Ungogo, and Kumbotso—fall into this category. Based on this, Kano State, particularly the KMA (Figure ​(Figure1),1), was the natural first choice for the survey. Figure 1. A map of the study area, Kano Metropolitan Area, in Kano State, northern Nigeria. Abbreviation: LGA, local government area. Previous work has been done to measure and report the seroprevalence of polio serotypes among different age groups. Giwa et al reported that seroprevalence to poliovirus serotypes, although higher than values found in previous studies done in Nigeria, was lower than in the developed world [11]. This was corroborated by Iliyasu et al, who submitted that seroprevalence levels found in their survey, specific to Kano, were much lower than in corresponding serosurveys in Egypt and India [12, 13] and are insufficient to interrupt poliovirus transmission [14]. We present results of serial health facility–based polio seroprevalence surveys conducted in the 8 urban LGAs of KMA in Kano State, focusing on infants aged 6–9 months and comparing their seroprevalence levels in 2011, 2013, and 2014 to show how findings of these SPS have been used to review the polio eradication program in Nigeria and to subsequently develop innovative strategies for polio eradication.

Structural and Magnetic Properties of Dilute Ca²⁺ Doped Iron Oxide Nanoparticles

Abstract: Undoped and calcium substituted hematite (α-Fe₂O₃) nanoparticles are synthesized by surfactant-directed co-precipitation and post annealing method. The annealed nanoparticles were found to be in single phase in nature and crystallize in the rhombohedral structure with space group R3c as confirmed by Rietveld refinement of the X-ray diffraction (XRD) data. Average crystallite sizes are calculated to be 20 to 30 nm and 50 to 60 nm for the nanoparticles annealed at 400 and 600 °C respectively. Mossbauer spectra for all the nanoparticles could be fitted with a sextet corresponding to the single magnetic state of the iron atoms in its Fe³⁺ state in the hematite matrix. The FTIR and Raman spectra of all the samples correspond to specific modes of α-Fe₂O₃. UV-Vis spectra of annealed samples showed broad peaks in the range of 525-630 nm resulting from spin-forbidden ligand field transition together with the spin-flip transition among the 2t₂g states. The estimated band gap energies were in the range of 1.6 to 1.9 eV which are much lower than the reported values for nano hematite. From the room temperature magnetic hysteresis loop measurements, weak ferromagnetic behavior is observed in all undoped and Ca²⁺ doped hematite samples. Morin temperature (T(M)) is calculated to be 257 and 237 K for 1.45% doped samples with particle size 54 and 27 nm respectively. The sample with Ca content of 1.45 wt% when annealed at 400 °C showed that the particles were of different shapes which included both quasi spherical and rod shaped. On annealing the same sample at 600 °C, the nanorods collapsed to form bigger spherical and ellipsoidal particles.