Subhash Chandir

The feasibility of using mobile-phone based SMS reminders and conditional cash transfers to improve timely immunization in rural Kenya ☆

BACKGROUND Demand-side strategies could contribute to achieving high and timely vaccine coverage in rural Africa, but require platforms to deliver either messages or conditional cash transfers (CCTs). We studied the feasibility of using short message services (SMS) reminders and mobile phone-based conditional cash transfers (CCTs) to reach parents in rural Western Kenya. METHODS In a Health and Demographic Surveillance System (HDSS), mothers with children aged 0-3 weeks old were approached to determine who had access to a mobile phone. SMS reminders were sent three days prior to and on the scheduled day of immunization for 1st (age 6 weeks) and 2nd doses (age 10 weeks) of DTP-HepB-Hib (Pentavalent) vaccine, using open-source Rapid SMS software. Approximately

Effect of food coupon incentives on timely completion of DTP immunization series in children from a low-income area in Karachi, Pakistan: A longitudinal intervention study

2.00 USD was sent as cash using mPESA, a mobile money transfer platform (2/3 of mothers), or airtime (1/3 of mothers) via phone if the child was vaccinated within 4 weeks of the scheduled date. Follow-up surveys were done when children reached 14 weeks of age. RESULTS We approached 77 mothers; 72 were enrolled into the study (26% owned a phone and 74% used someone elses). Of the 63 children with known vaccination status at 14 weeks of age, 57 (90%) received pentavalent1 and 54 (86%) received pentavalent2 within 4 weeks of their scheduled date. Of the 61 mothers with follow-up surveys administered at 14 weeks of age, 55 (90%) reported having received SMS reminders. Of the 54 women who reported having received SMS reminders and answered the CCT questions on the survey, 45 (83%) reported receiving their CCT. Most (89%) of mothers in the mPESA group obtained their cash within 3 days of being sent their credit via mobile phone. All mothers stated they preferred CCTs as cash via mobile phone rather than airtime. Of the 9 participants who did not vaccinate their children at the designated clinic 2(22%) cited refusals by husbands to participate in the study. CONCLUSION The data show that in rural Western Kenya mobile phone-based strategies are a potentially useful platform to deliver reminders and cash transfers. Follow-up studies are needed that provide evidence for the effectiveness of these strategies in improving vaccine coverage and timeliness.

The Differential Impact of Coadministered Vaccines, Geographic Region, Vaccine Product and Other Covariates on Pneumococcal Conjugate Vaccine Immunogenicity

This study introduced food/medicine vouchers as an incentive to mothers of infants visiting Expanded Program on Immunization (EPI) centers in a low socio-economic area. The timely completion of diphtheria, tetanus and pertussis vaccines combined (DTP) series immunization rates between intervention and control cohorts were compared. The DTP up-to-date immunization coverage at 18 weeks of age increased two-fold (RR 2.20, 95% CI: 1.95-2.48, p<0.001) in the incentive cohort compared to the no-incentive cohort. While increasing immunization coverage is a complex structural and behavioral process, food/medicine coupon may improve routine immunization coverage in developing countries.

Effect of Buffer on the Immune Response to Trivalent Oral Poliovirus Vaccine in Bangladesh: A Community Based Randomized Controlled Trial

Background: Antipneumococcal capsular polysaccharide antibody concentrations are used as predictors of vaccine efficacy against vaccine serotype (ST) pneumococcal disease among infants. While pneumococcal conjugate vaccines (PCV) are recommended globally, factors associated with optimal PCV immune response are not well described. We aimed to systematically assess local setting factors, beyond dosing schedule, which may affect PCV antibody levels. Methods: We conducted a literature review of PCV immunogenicity, abstracting data from published reports, unpublished sources, and conference abstracts from 1994 to 2010 (and ad hoc 2011 reports). Studies included in this analysis evaluated ≥ 2 primary doses of PCV before 6 months of age in non–high-risk populations, used 7-valent or higher PCV products (excluding Aventis-Pasteur and Merck products) and provided information on geometric mean concentration (GMC) for STs 1, 5, 6B, 14, 19F or 23F. Using random effects meta-regression, we assessed the impact of geographic region, coadministered vaccines and PCV product on postprimary GMC, adjusting for dosing schedule and ELISA laboratory method. Results: Of 12,980 citations reviewed, we identified 103 vaccine study arms for this analysis. Children in studies from Asia, Africa and Latin America had significantly higher GMC responses compared with those in studies from Europe and North America. Coadministration with acellular pertussis DTP compared with whole-cell DTP had no effect on PCV immunogenicity except for ST14, where GMCs were higher when coadministered with acellular pertussis DTP. Vaccine product, number of PCV doses, dosing interval, age at first dose and ELISA laboratory method also affected the GMC. Conclusions: PCV immunogenicity is associated with geographic region and vaccine product; however, the associations and magnitude varied by ST. Consideration of these factors is essential when comparing PCV immunogenicity results between groups and should be included in the evidence base when selecting optimal PCV vaccine schedules in specific settings.

Coverage, timeliness, and determinants of immunization completion in Pakistan: Evidence from the Demographic and Health Survey (2006–07)

BACKGROUND Polio eradication efforts have been hampered by low responses to trivalent oral poliovirus vaccine (tOPV) in some developing countries. Since stomach acidity may neutralize vaccine viruses, we assessed whether administration of a buffer solution could improve the immunogenicity of tOPV. METHODS Healthy infants 4-6 weeks old in Sylhet, Bangladesh, were randomized to receive tOPV with or without a sodium bicarbonate and sodium citrate buffer at age 6, 10, and 14 weeks. Levels of serum neutralizing antibodies for poliovirus types 1, 2, and 3 were measured before and after vaccination, at 6 and 18 weeks of age, respectively. FINDINGS Serologic response rates following 3 doses of tOPV for buffer recipients and control infants were 95% and 88% (P=.065), respectively, for type 1 poliovirus; 95% and 97% (P=.543), respectively, for type 2 poliovirus; and 90% and 89% (P=.79), respectively, for type 3 poliovirus. CONCLUSIONS Administration of a buffer solution prior to vaccination was not associated with statistically significant increases in the immune response to tOPV; however, a marginal 7% increase (P=.065) in serologic response to poliovirus type 1 was observed. CLINICAL TRIALS REGISTRATION NCT01579825.

Immune response to 1 and 2 dose regimens of measles vaccine in Pakistani children.

Background: Immunization coverage data and determinants for completion are not well described for Pakistan. This study determines immunization coverage rates and timeliness based on the 2006–07 Pakistan Demographic and Health Survey (DHS) and identifies determinants for completion of immunizations. Methods: DHS data from 9177 randomly selected households from across Pakistan were analyzed to assess immunization coverage and timeliness for children aged 0–5 years, and to investigate determinants of immunization completion through logistic regressions. Results: The proportion of children immunized for a third dose of the oral poliovirus vaccine (OPV3) was 80.3%, and combination diphtheria, tetanus, and pertussis vaccines (DTP3) was 55.9%. Measles coverage was 62.5%. Late immunizations were most likely to occur for third doses of the OPV (65.5%) and DTP series (65.5%). Early doses were most likely to be administered for measles (21.9%). The proportion of children not immunized for any vaccine was 6.2%. Receiving a dose of maternal tetanus was a major determinant for immunization completion for OPV3 (OR 1.35, 95% CI: 1.14–1.60), DTP3 (OR 2.54, 95% CI: 2.13–3.02), and measles (OR 2.78, 95% CI: 2.27–3.40). Other independent variables associated with improved immunization completion included higher household wealth and maternal education. Conclusion: Poor routine immunization coverage and timeliness were identified through the DHS in Pakistan. Encouraging maternal tetanus uptake among women of child-bearing age and greater integration of immunization services with antenatal care may help improve childhood immunization completion.

Using Predictive Analytics to Identify Children at High Risk of Defaulting From a Routine Immunization Program: Feasibility Study

Measles is a significant problem in Pakistan despite vaccine coverage rates reported at 80%. The purpose of this study was to determine the serologic response in children after one dose of measles vaccine at 9 mo versus two doses at 9 and 15 mo of age. From March through December 2006, children were enrolled from immunization clinics and squatter settlements in Karachi. Blood samples were taken from children in Group A at 9–10 mo of age prior to measles vaccine and 8 to 11 weeks later; from children in Group B at 16–17 mo of age after receiving 2 doses of measles vaccine; and from children in Group C who had received at least one dose of measles vaccine by 5 y of age. After the first dose of measles vaccine, 107/147 (73%) of children in Group A were seropositive, 157/180 (87%) of children in Group B were seropositive after two doses and 126/200 (63%) of children in Group C were seropositive at 5 y of age. The post-vaccination geometric mean antibody concentrations were higher in females than males in groups A (irrespective of pre-vaccination antibody levels) and B. The serologic response to one and two doses of measles vaccine was lower in children in Karachi than has been reported in many other countries. Two doses of vaccine were significantly better than one dose. An in-depth investigation is needed to determine the reason for the lower-than-expected protection rates. Differences in immunogenicity between genders need to be further studied. Recent introduction of supplemental measles vaccine doses should help control measles in Pakistan.

Feasibility of using global system for mobile communication (GSM)-based tracking for vaccinators to improve oral poliomyelitis vaccine campaign coverage in rural Pakistan

Background Despite the availability of free routine immunizations in low- and middle-income countries, many children are not completely vaccinated, vaccinated late for age, or drop out from the course of the immunization schedule. Without the technology to model and visualize risk of large datasets, vaccinators and policy makers are unable to identify target groups and individuals at high risk of dropping out; thus default rates remain high, preventing universal immunization coverage. Predictive analytics algorithm leverages artificial intelligence and uses statistical modeling, machine learning, and multidimensional data mining to accurately identify children who are most likely to delay or miss their follow-up immunization visits. Objective This study aimed to conduct feasibility testing and validation of a predictive analytics algorithm to identify the children who are likely to default on subsequent immunization visits for any vaccine included in the routine immunization schedule. Methods The algorithm was developed using 47,554 longitudinal immunization records, which were classified into the training and validation cohorts. Four machine learning models (random forest; recursive partitioning; support vector machines, SVMs; and C-forest) were used to generate the algorithm that predicts the likelihood of each child defaulting from the follow-up immunization visit. The following variables were used in the models as predictors of defaulting: gender of the child, language spoken at the child’s house, place of residence of the child (town or city), enrollment vaccine, timeliness of vaccination, enrolling staff (vaccinator or others), date of birth (accurate or estimated), and age group of the child. The models were encapsulated in the predictive engine, which identified the most appropriate method to use in a given case. Each of the models was assessed in terms of accuracy, precision (positive predictive value), sensitivity, specificity and negative predictive value, and area under the curve (AUC). Results Out of 11,889 cases in the validation dataset, the random forest model correctly predicted 8994 cases, yielding 94.9% sensitivity and 54.9% specificity. The C-forest model, SVMs, and recursive partitioning models improved prediction by achieving 352, 376, and 389 correctly predicted cases, respectively, above the predictions made by the random forest model. All models had a C-statistic of 0.750 or above, whereas the highest statistic (AUC 0.791, 95% CI 0.784-0.798) was observed in the recursive partitioning algorithm. Conclusions This feasibility study demonstrates that predictive analytics can accurately identify children who are at a higher risk for defaulting on follow-up immunization visits. Correct identification of potential defaulters opens a window for evidence-based targeted interventions in resource limited settings to achieve optimal immunization coverage and timeliness.