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Background: Pakistan has a well-established Expanded Program on Immunization (EPI) however vaccine-preventable diseases still account for high infant and child mortality rates. This study describes the differential vaccine coverage and determinants of vaccine uptake in rural Pakistan., Methods: From October 2014 to September 2018, we enrolled children younger than 2 years of age from the Matiari Demographic Surveillance System in Sindh, Pakistan. Socio-demographic and vaccination history were collected from all participants. Vaccine coverage rates and timeliness were reported. Socio-demographic variables for missed and untimely vaccination were studied in multivariable logistic regression., Results: Of the 3140 enrolled children, 48.4 % received all EPI recommended vaccines. Only 21.2 % of these were age appropriate. Around 45.4 % of the children were partially vaccinated, and 6.2 % were unvaccinated. Highest coverage was seen for the first dose of pentavalent (72.8 %), 10-valent Pneumococcal Conjugate Vaccine (PCV10) (70.4 %) and Oral Polio Vaccine (OPV) (69.2 %) and the lowest coverage was for measles (29.3 %) and rotavirus (1.8 %) vaccines. Primary caretakers and wage earners with a higher level of education were protective against missed and untimely vaccination. Enrollment in the 2nd, 3rd and 4th study year was negatively associated with being unvaccinated whereas distance from a major road was positively associated with non-adherence to schedule., Conclusion: Vaccine coverage was low among children in Matiari, Pakistan, and majority received delayed doses. Parents' education status and year of study enrollment was protective against vaccine dropout and delayed vaccination whereas geographical distance from a major road was a predictor. Vaccine promotion and outreach efforts may have had a beneficial impact on vaccine coverage and timeliness., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background: Rotavirus vaccination introduction in routine immunization is under consideration in Pakistan. Data on the baseline epidemiology of intussusception will inform surveillance strategies for intussusception after rotavirus vaccine introduction in Pakistan. We describe the epidemiology of intussusception-associated hospitalizations among children <2years of age in Karachi, Pakistan., Methods: We conducted a retrospective chart review for July 01, 2012 through June 30, 2015 at the National Institute of Child Health (NICH) and Aga Khan University Hospital (AKUH) Karachi. At AKUH, the International Classification of Disease, ninth revision, code 560.0 for intussusception was used to retrieve intussusception case records. At NICH, daily Operation Theater, Emergency Room, and surgical daycare log sheets and surgical ward census sheets were used to identify cases. Records of children who fulfilled eligibility criteria and the Brighton Collaboration level one case definition of intussusception were selected for data analysis. We used structured case report forms to extract data for the descriptive analysis., Results: We identified 158 cases of confirmed intussusception; 30 cases (19%) were from AKUH. More than half (53%) of the cases occurred in children aged 6-12months, followed by 35% among those aged <6months. Two-thirds (106/158) of the cases were male. The most common presenting complaints were vomiting and bloody stool. At NICH, almost all (93%) were managed surgically, while at AKUH, ∼57% of the cases were managed with enemas. Three deaths occurred, all from NICH. Cases occurred without any seasonality. At NICH, 4% (128/3618) of surgical admissions among children aged <2years were attributed to intussusception, while that for AKUH was 2% (30/1702)., Conclusion: In this chart review, intussusception predominantly affected children 0-6months of age and occurred more commonly in males. This information on the baseline epidemiology of intussusception will inform post-vaccine introduction adverse event monitoring related to intussusception in Pakistan., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Intussusception is the invagination of one segment of the bowel into a distal segment, characterized by symptoms of bloody stool, vomiting, and abdominal pain. Previous studies have found regional differences in incidence but the etiology of most intussusception cases is unknown. Rotavirus vaccines were associated with a slightly of increased risk of intussusception in post-licensure evaluations in high- and middle-income countries, but not in low income African countries. To describe the baseline epidemiology of intussusception in young children prior to rotavirus vaccine implementation, active sentinel hospital surveillance for intussusception in children < 2 years of age was conducted in 4 low income Asian countries (Bangladesh, Nepal, Pakistan and Vietnam). Over a 24-month period, 15 sites enrolled 1,415 intussusception cases, of which 70% were enrolled in Vietnam. Overall, 61% of cases were male and 1% (n = 16) died, ranging from 8% in Pakistan to 0% in Vietnam. The median age of cases enrolled ranged from 6 months in Bangladesh and Pakistan to 12 months in Vietnam. The proportion of cases receiving surgical management was 100% in Bangladesh, 88% in Pakistan, 61% in Nepal, and 1% in Vietnam. The high proportion of males and median age of cases around 6 months of age found in this regional surveillance network are consistent with previous descriptions of the epidemiology of intussusception in these countries and elsewhere. Differences in management and the fatality rate of cases between the countries likely reflect differences in access to healthcare and availability of diagnostic modalities. These baseline data will be useful for post-rotavirus vaccine introduction safety monitoring., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Background: Maternal vaccines against pertussis are not yet recommended in the developing world. Besides unclear burden estimates, another concern is that transplacental transfer of maternal pertussis antibodies could result in attenuation of the immune response to whole cell pertussis (DTwP) primary vaccination series in infants. This study was taken up to determine whether higher levels of maternal pertussis antibodies attenuate immune response of infants to DTwP vaccination series given at 6-10-14 weeks of age., Methodology: A total of 261 pregnant women and their infants from four low-income settlements in Karachi, Pakistan were enrolled in this study. The study endpoints were infant antibody titers for Pertussis toxin (PTx), Filamentous hemagglutinin antigen (FHA), Pertactin (PRN) and Fimbriae type 2/3 (FIM) - from birth through 18 weeks of age. Cord blood or pre-vaccine pertussis antibody titers indicate the concentration of maternal antibodies transferred to infants. Linear regression models were used to determine the association between higher maternal antibody titers and infant immune response to DTwP vaccine. Geometric Mean Ratio (GMR) was calculated as the ratio of infant antibody titers at specified time points against the maternal antibody titers at the time of delivery., Results: At eighteen weeks of age, the adjusted β regression coefficient for PTx was 0.06 (95% CI: -0.49-0.61), FHA 0.02 (95% CI: -0.26 -0.29), PRN 0.02 (95%CI -0.38- 0.43), and FIM 0.17 (95%CI: -0.21-0.54). Among infants who received at least two doses of DTwP vaccine, higher maternal antibody titers did not have any attenuating effect on infant post-immunization antibody titers against all four pertussis antigens., Conclusion: Maternal pertussis antibodies did not attenuate infant's immune response to pertussis antigens in DTwP primary vaccine given at 6-10-14 weeks of age., (Copyright © 2018 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Since its inception in 1978, Pakistan's Expanded Programme on Immunization (EPI) has contributed significantly towards child health and survival in Pakistan. However, the WHO-estimated immunization coverage of 88% for 3 doses of Diptheria-Tetanus-Pertussis vaccine in Pakistan is likely an over-estimate. Many goals, such as polio, measles and neonatal tetanus elimination have not been met. Pakistan reported more cases of poliomyelits in 2011 than any other country globally, threatening the Global Polio Eradication Initiative. Although the number of polio cases decreased to 58 in 2012 through better organized supplementary immunization campaigns, country-wide measles outbreaks with over 15,000 cases and several hundred deaths in 2012-13 underscore sub-optimal EPI performance in delivering routine immunizations. There are striking inequities in immunization coverage between different parts of the country. Barriers to universal immunization coverage include programmatic dysfunction at lower tiers of the program, socioeconomic inequities in access to services, low population demand, poor security, and social resistance to vaccines among population sub-groups. Recent conflicts and large-scale natural disasters have severely stressed the already constrained resources of the national EPI. Immunization programs remain low priority for provincial and many district governments in the country. The recent decision to devolve the national health ministry to the provinces has had immediate adverse consequences. Mitigation strategies aimed at rapidly improving routine immunization coverage should include improving the infrastructure and management capacity for vaccine delivery at district levels and increasing the demand for vaccines at the population level. Accurate vaccine coverage estimates at district/sub-district level and local accountability of district government officials are critical to improving performance and eradicating polio in Pakistan., (Copyright © 2013 Elsevier Ltd. All rights reserved.)