Maternally transmitted anti-measles antibodies, and susceptibility to disease among infants in Chandigarh, India: A prospective birth cohort study.

Prior to the age of measles vaccination, infants are believed to be protected against measles by passively transferred maternal antibodies. However, the quantity and quality of such protection have not been well established in the Indian setting. We undertook this study to characterize the transfer and decline in maternal anti-measles antibodies among infants, and determine their susceptibility to measles. In this population-based, birth-cohort study, we enrolled pregnant women and their newborn infants, from a catchment area of 30 Anganwadis in Chandigarh, India. We collected maternal blood at delivery, and infant blood samples at birth, and 3, 6, and 9 months of age. Anti-measles IgG antibodies were measured using quantitative ELISA. We assessed antibody decline using log-linear models. In total, 428 mother-infant dyads were enrolled, and data from 413 dyads were analyzed. At birth, 91.5% (95% CI: 88.8, 94.2) of infants had protective antibody levels, which declined to 26.3% (95% CI: 21.0%, 31.9) at 3 months, 3.4% (95% CI: 0.9, 5.9) at 6 months, and 2.1% (95% CI: 0.1, 4.1) at 9 months. Younger mothers transferred lower levels of antibodies to their infants. We concluded that the majority of infants are susceptible to measles as early as three months of age, much earlier than their eligibility to receive measles vaccination.

Measles seroprevalence in persons over one year of age in Chandigarh, India.

Measles continues to result in focal outbreaks in India, despite over three decades of universal infant vaccination. The aims of this study were to examine measles immunity in the population of Chandigarh, India, and to compare immunity by vaccination vs. natural infection. In a cross-sectional study of individuals 1-60 years selected from 30 communities within Chandigarh during 2017-2018, measles immunity was assessed using serological surveys. Seropositivity was compared across demographic groups, and by prior history of vaccination and natural history of infection. Among those 1-20 years old, measles seropositivity, and histories of measles vaccination or prior measles diagnosis were separately assessed as outcomes in logistic regression models, with demographic factors as independent variables. Among 1690 participants, 94% were seropositive, and 6% had borderline or negative antibody levels. Of those positive, 30% had prior vaccination, 16% had a history of natural infection, and 54% had an unknown history. Over 50% of individuals among those >20 years old, had unknown history of immunity. In the multivariable regression models, vaccination was more common in younger ages (P < .0001), and in males compared to females (P = .0220), and in those with more education (P < .0001). The majority of the population was seropositive, and seropositivity increased with age. Older age groups were more likely to be protected because of previous natural infection, whereas younger age groups were protected by vaccination. There was inequity in vaccination coverage by gender, and maternal education status.

Measles Vaccination Immunogenicity and Association with Caste in Chandigarh, India.

Measles affects those of lower socioeconomic status disproportionately. This study evaluated the impact of measles vaccination on antibody titers 3 months after vaccination across different socioeconomic groups, with a focus on caste. In total, 169 infants in Chandigarh, India, had serum samples collected immediately prior to vaccination at 9 months of age and 3 months later. Overall, 126 infants (76%) were seropositive (antibody titers > 12 mIU/mL), 26 (16%) were borderline (8-12 mIU/mL), and 14 (8%) were seronegative (< 8 mIU/mL). Seropositivity (versus borderline/seronegative infants) was 0.78 times as high among individuals from the historically marginalized scheduled castes/scheduled tribes compared with the others caste grouping (95% CI, 0.62-0.98). Antibody response was not tied to anthropometric measures but was attenuated among scheduled castes/scheduled tribes with higher incomes. This study provides observational evidence that social structures can be associated with individual immune responses.

Analysis of reasons for loss to follow up in a prospective study in Chandigarh, India and impact from telecom changes.

OBJECTIVE: Mobile phones are used in research studies, to enroll and follow-up participants, collect data, and implement mHealth initiatives. We conducted a longitudinal study in a birth cohort, where infants were required to make four scheduled visits by 12 months of age. Families of those failing to attend scheduled follow-up visits, were contacted telephonically to ascertain the reasons, which were categorized as: not interested to continue participating, migrated, phone disconnected due to telecom change, or other reason. RESULTS: A total of 413 mother-infant dyads were enrolled. The overall attrition was 56%, with majority occurring at the first follow-up visit. This temporally coincided with a telecom service provider announcing strong incentives to switch providers. Attrition monotonically decreased at subsequent visits. The reasons were: moved away (13%), no longer interested (8%), phone disconnected (7%), and multiple other reasons (28%), the majority of whom had unreachable phones. Those who remained in the study and those lost to follow-up were similar on most demographic variables. Among common reasons for attrition in cohort studies, we experienced a new dimension introduced by telecom changes. These findings underscore the need to consider unexpected reasons for attrition in longitudinal studies, and design more robust methods to follow-up participants.

Immunization status of children in Nepal and associated factors, 2016.

BACKGROUND: Nepal has made substantial improvements in childhood immunization uptake. However, vaccination levels are still below the country-specific Sustainable Development Goal target of 94.8% coverage by 2025 for children aged 12-23 months who received all immunizations recommended in the national immunization schedule by their first birthday. A better understanding of the predictors of full immunization can inform successful programmatic interventions to improve coverage while also guiding resource allocation to ensure all children are fully vaccinated. This study estimates childhood immunization coverage in Nepal and characterizes the association between immunization status and various sociodemographic predictors. METHODS: Data from the 2016 Nepal Demographic and Health Survey were used to examine the immunization status of children aged 12-23 months. Immunization status was categorized as fully immunized (receiving all recommended doses), under-immunized (receiving at least one, but not all, recommended doses), and un-immunized (not receiving any doses of any vaccine). Associations between full and under-immunization and potential sociodemographic predictors were assessed using logistic regression. RESULTS: Among 976 children, 78.2% were fully immunized, 21% were under-immunized, and 0.8% were un-immunized. Retention of an immunization card was significantly associated with full immunization status. Mothers who had completed a formal education above secondary school and mothers who were working at time of interview had increased odds of full immunization. Birthing in an institutional setting was also associated with higher odds of full immunization. CONCLUSIONS: Overall, immunization coverage in Nepal is relatively high, although it varies by dose and sociodemographic factors. Almost 25% of Nepalese children were not fully immunized, leaving them at increased risk for vaccine-preventable disease related morbidity and mortality. Nepal must continue focused efforts to reach every child and minimize the equity gap; programs may focus on advocating for the use of immunization cards, education and empowerment for girls, and delivery in institutional settings.

Impact of Multiple Risk Factors on Vaccination Inequities: Analysis in Indian Infants Over 2 Decades.

INTRODUCTION: Several authors have explored the effect of individual risk factors on vaccination inequity in Indian infants. This study explores the combined impact of >1 risk factor on the probability of full vaccination. METHODS: The proportion of fully vaccinated infants (aged 1-2 years) was calculated from the National Family Health Survey conducted during 1997-1998 (National Family Health Survey-2, n=10,211), 2005-2006 (National Family Health Survey-3, n=9,582), and 2015-2016 (National Family Health Survey-4, n=48,715). Full vaccination was defined as receiving Bacille Calmette‒Guerin (1 dose); diphtheria, pertussis, tetanus (3 doses); oral polio (3 doses); and measles (1 dose) vaccines. The association between full vaccination status and 6 factors (infant sex, birth order, family wealth status, maternal education level, residence type, and religion) was analyzed individually, followed by the combined impact of ≥1 of the first 4, using logistic regression models. RESULTS: The AORs for full vaccination in the 3 surveys, respectively, were 1.09, 1.13, and 1.00 for male versus female infants; 0.68, 0.71, and 0.88 for birth order >1 versus birth order 1; 1.54, 1.96, and 1.20 for greater wealth versus lowest wealth stratum; 2.21, 2.27, and 1.27 for any maternal education versus none; 1.08, 1.10, and 1.08 for Hindu versus other religion; and 1.51, 1.10, and 0.88 for urban versus rural residence. The respective ORs of full vaccination in the 3 surveys by the number of risk factors were as follows: 1.26, 1.54, and 1.27 for 3 risk factors; 2.41, 3.23, and 1.68 for 2 risk factors; 4.42, 6.45, and 2.18 for 1 risk factor; and 7.32, 9.84, and 2.61 for no risk factor. CONCLUSIONS: The presence of multiple risk factors had a cumulative negative impact on infant vaccination in India. Despite an improvement over 2 decades, significant inequities persist. SUPPLEMENT INFORMATION: This article is part of a supplement entitled Global Vaccination Equity, which is sponsored by the Global Institute for Vaccine Equity at the University of Michigan School of Public Health.

Vaccination assessments using the Demographic and Health Survey, 2005-2018: a scoping review.

OBJECTIVE: To characterise studies which have used Demographic and Health Survey (DHS) datasets to evaluate vaccination status. DESIGN: Scoping review. DATA SOURCES: Electronic databases including PubMed, EBSCOhost and POPLINE, from 2005 to 2018. STUDY SELECTION: All English studies with vaccination status as the outcome and the use of DHS data. DATA EXTRACTION: Studies were selected using a predetermined list of eligibility criteria and data were extracted independently by two authors. Data related to the study population, the outcome of interest (vaccination) and commonly seen predictors were extracted. RESULTS: A total of 125 articles were identified for inclusion in the review. The number of countries covered by individual studies varied widely (1-86), with the most published papers using data from India, Nigeria, Pakistan and Ethiopia. Many different definitions of full vaccination were used although the majority used a traditional schedule recommended in the WHO's Expanded Programme on Immunisation. We found studies analysed a wide variety of predictors, but the most common were maternal education, wealth, urbanicity and child's sex. Most commonly reported predictors had consistent relationships with the vaccination outcome, outside of sibling composition. CONCLUSIONS: Researchers make frequent use of the DHS dataset to describe vaccination patterns within one or more countries. A clearer idea of past use of DHS can inform the development of more rigorous studies in the future. Researchers should carefully consider whether a variable needs to be included in the multivariable model, or if there are mediating relationships across predictor variables.

Demographics of Vaccine Hesitancy in Chandigarh, India.

The impact of vaccine hesitancy on childhood immunization in low- and middle-income countries remains largely uncharacterized. This study describes the sociodemographic patterns of vaccine hesitancy in Chandigarh, India. Mothers of children <5 years old were sampled from a two-stage cluster, systematic sample based on Anganwadi child care centers in Chandigarh. Vaccine hesitancy was measured using a 10-item Vaccine Hesitancy Scale, which was dichotomized. A multivariable logistic regression assessed the association between socioeconomic factors and vaccine hesitancy score. Among 305 mothers, >97% of mothers thought childhood vaccines were important, effective, and were a good way to protect against disease. However, many preferred their child to receive fewer co-administered vaccines (69%), and were concerned about side effects (39%). Compared to the "other caste" group, scheduled castes or scheduled tribes had 3.48 times greater odds of vaccine hesitancy (95% CI: 1.52, 7.99). Those with a high school education had 0.10 times the odds of vaccine hesitancy compared to those with less education (95% CI: 0.02, 0.61). Finally, those having more antenatal care visits were less vaccine hesitant (≥4 vs. <4 visits OR: 0.028, 95% CI: 0.1, 0.76). As India adds more vaccines to its Universal Immunization Program, consideration should be given to addressing maternal concerns about vaccination, in particular about adverse events and co-administration of multiple vaccines.

Vaccination timeliness among newborns and infants in Ethiopia.

BACKGROUND: We characterize the risk factors for delayed polio dose 1, diphtheria-tetanus-pertussis (DTP) dose 1, pentavalent dose 1, and measles dose 1 in Ethiopian infants. We also examine the interaction between institutional delivery and demographic factors on the birth doses of the BCG and polio vaccines to better understand factors influencing vaccination. METHODS: Using the 2011 Ethiopia Demographic and Health Survey, we calculated the distribution of the study population across different demographic and vaccination characteristics. We computed acceleration factors using a multivariable accelerated failure time model with a Weibull distribution to account for left and right censoring. For the birth doses, we further specified an interaction term between institutional delivery and every other a priori specified independent variable to test whether institutional delivery modifies sociodemographic disparities in vaccination timeliness. RESULTS: Low wealth status, home delivery, and ethnicity are risk factors for delayed vaccination of polio 1, DPT 1, pentavalent 1, and measles 1. Religion is a risk factor for measles 1 vaccination delay and rural residence are risk factors for delayed DPT1 and polio 1 doses. For birth doses of polio and BCG, institutional delivery attenuated many sociodemographic disparities in vaccination delay, except for urbanicity, which showed rural dwellers with more delay than urban dwellers with an institutional vs home birth. CONCLUSIONS: Less delayed vaccination among children with institutional deliveries highlights the importance of perinatal care and the potential for promoting healthy behaviors to parents. Persistent disparities between urban and rural residents, even among those with institutional births, can be targeted for future interventions. Timely vaccination is key to prevention of unnecessary childhood mortality.

Childhood vaccination in Kenya: socioeconomic determinants and disparities among the Somali ethnic community.

OBJECTIVES: Kenya has a significant refugee population, including large numbers of Somali migrants. This study examines the vaccination status of Kenyan children and sociodemographic predictors of vaccination, including Somali ethnicity. METHODS: Using the 2014 Kenyan Demographic and Health Survey, we calculated the proportion of non-vaccinated, under-vaccinated, and fully vaccinated children, defining full vaccination as one dose Bacille Calmette-Guerin, three doses polio, three doses pentavalent, and one dose measles. We assessed associations among various factors and vaccination status using multinomial logistic regression and explored the effect of Somali ethnicity through interaction analysis. RESULTS: The study sample comprised 4052 children aged 12-23 months, with 79.4% fully, 19.0% under-, and 1.6% non-vaccinated. Among Somalis, 61.9% were fully, 28.7% under-, and 9.4% non-vaccinated. Somalis had significantly greater odds of under- and non-vaccination than the Kikuyu ethnic group. Wealth and birth setting were associated with immunization status for Somalis and non-Somalis. CONCLUSIONS: Disparities persist in pediatric vaccinations in Kenya, with Somali children more likely than non-Somalis to be under-vaccinated. Health inequalities among migrants and ethnic communities in Kenya should be addressed.

Childhood full and under-vaccination in Nigeria, 2013.

BACKGROUND: Nigeria's government is challenged with vaccinating the world's third largest birth cohort within a culturally and socioeconomically diverse country. This study estimated full childhood immunization coverage in Nigeria and characterizes the association between vaccination status and urbanicity, region of residence, ethnicity, and other factors. METHODS: In 2013, households throughout Nigeria were enrolled in the Demographic and Health Survey which included questions about vaccination. We defined full vaccination of a child as having received a single dose of bacillus Calmete-Guerin (BCG), one dose of measles-containing vaccine (MCV), three doses of diphtheria, pertussis, tetanus (DPT), and four doses of oral polio vaccine (OPV). Using a multinomial logistic regression model, full vaccination and under-vaccination versus non-vaccination was regressed onto various demographic and socioeconomic characteristics. RESULTS: Among 5759 children 1 year of age, 25.5% were fully vaccinated, 47.9% were under-vaccinated, and 26.6% had not received any vaccinations. Children were more likely to be fully vaccinated if they belonged to wealthier families, resided in southern regions of the country, were Christian, belonged to the Igbo or Yoruba ethnic group, had mothers who made ≥5 antenatal care visits, delivered at an institution, or were more highly educated. CONCLUSIONS: Full vaccination among children in Nigeria is exceptionally low by global standards and certain groups, such as Muslims and individuals in northern regions who are higher risk of non- or under-vaccination should be targeted by vaccination programs. Providing a wide range of health care services for mothers and pregnant women could improve full vaccination of children.

Vaccination status of children aged 1-4 years in Afghanistan and associated factors, 2015.

BACKGROUND: Childhood mortality in Afghanistan fell by half between 1990 and 2015, due in part to the government's commitment to improving pediatric immunization services. Although progress has been made, immunization coverage has nonetheless remained low with only 65% of children receiving the third dose of Diphtheria-Pertussis-Tetanus (DPT3) based on WHO estimates. This study aims to calculate the proportion of Afghan children aged 1-4 years who were fully vaccinated, under-vaccinated, or non-vaccinated with government-recommended Expanded Program on Immunization vaccines and identify predictors related to the family's sociodemographic status and maternal autonomy. METHODS: Data from the 2015 Afghanistan Demographic and Health Survey was used to calculate the proportion of children who were fully vaccinated (i.e. received all recommended vaccines), under-vaccinated (i.e. received some, but not all), and non-vaccinated (i.e. did not receive any vaccines) according to WHO guidelines. A multivariable multinomial logistic regression model generated odds ratios for under-vaccination and non-vaccination versus full vaccination, and examined associations between independent factors and full vaccination status. RESULTS: We found 40.6% of Afghan children age 1-4 were fully vaccinated, 42.4% under-vaccinated, and 17% non-vaccinated. Large disparities characterized immunization coverage among provinces and between urban and rural regions. Birthing in a government institution (vs. non-institutional setting), a higher number of antenatal care visits, and a visit to a health facility in the past 12 months were all associated with increased odds of full immunization. Factors related to maternal autonomy including maternal decision-making and maternal attitudes towards beating were also significantly associated with vaccination status. CONCLUSION: Approximately 60% of children in Afghanistan are under-vaccinated or non-vaccinated, leaving millions of children unnecessarily at risk for vaccine-preventable diseases. Engagement with community and religious leaders to create programs that increase women's autonomy and expand access to institutional delivery could lead to downstream increases in childhood vaccination coverage.

Causality assessment of serious and severe adverse events following immunization in India: a 4-year practical experience.

BACKGROUND: India has implemented the World Health Organization's revised Causality Assessment Protocol for adverse events following immunization (AEFI). We describe the number and types of serious/severe AEFIs, including deaths. RESEARCH DESIGN AND METHODS: Analysis of causality classification of reported serious/severe AEFIs from 1 January 2012 to 7 January 2016 was done. Classification includes (A) consistent with causal association to immunization; (B) indeterminate; (C) coincidental association; or (D) unclassifiable. We present descriptive statistics across each category. RESULTS: Analysis of causality assessment completed for 1037 reports of serious AEFIs: 499 (48%) were causally associated, 84 (8%) were indeterminate, 323 (31%) were coincidental, and 131 (13%) were unclassifiable. Of the 499 reports in the A category, the events were causally linked to vaccine product for 189 (18%), to immunization error for 135 (13%), and to immunization anxiety for 175 (17%). Among 279 reported deaths, more than half (55%; n = 153) were coincidental events and 37% were unclassifiable. CONCLUSIONS: Causality assessment of AEFI cases is an important component of vaccination programs and post-marketing surveillance of vaccines. Field reporting and investigation of AEFIs can be improved for many severe or serious reports, most of which are not causally linked to the vaccination program.

Predictors and Barriers to Full Vaccination among Children in Ethiopia.

Predictors of immunization status outside of large cities in Ethiopia are not well known, and Muslims have lower vaccination coverage. The aim of this study is to assess factors associated with full immunization among children 12-23 months in Worabe, Ethiopia, a Muslim-majority community. A cross-sectional study is conducted in summer 2016. Multivariable logistic regression was used to assess the significance of predictors of full immunization. Among 484 children, 61% are fully vaccinated. Children whose mothers had fewer antenatal care (ANC) visits have decreased odds of full vaccination (zero visits: odds ratio (OR) = 0.09; one visit: OR = 0.15; two visits: OR = 0.46; three visits: OR = 0.89). The most common reasons that the mother gave for not vaccinating the child are fear of side reactions (36%), being too busy (31%), or hearing rumors about vaccines (28%). Local interventions incorporating interventions with religious authorities could raise awareness in the community of the importance of childhood immunizations and ANC visits.

Parapoxvirus Infections in the Country of Georgia: A Case Series.

Infections caused by viruses of the parapoxvirus (PPV) genus, including orf and pseudocowpox viruses, are frequently seen in both humans and animals in many regions of the world. These infections are often misdiagnosed or neglected because of the lack of clinician awareness, inadequate diagnostic capacity, and their relatively mild disease presentation, which may result in affected individuals not seeking medical attention. Although PPV infections should be routinely considered in patients with cutaneous lesions, especially in those who have occupational exposure to farm animals, they are often excluded from the differential diagnosis because they are not perceived as serious, resulting in underestimation of the burden of disease. Since 2014, significant enhancements to Georgia's epidemiologic and laboratory capacity have made PPV surveillance and detection possible. In this study, we present information on 27 confirmed cases of PPV infection reported to Georgia's national surveillance system from January 2016 through January 2017.

Vaccination timeliness and co-administration among Kenyan children.

BACKGROUND: Timely administration of recommended vaccines requires children to have multiple vaccines co-administered in the first year of life. The objectives of this study were to estimate the proportion of timely vaccinations and the proportion of co-administered vaccines, and to assess the relationship between vaccine co-administration and vaccine timeliness in Kenyan children. METHODS: Using the 2014 Kenyan Demographic and Health Survey (DHS), we calculated the proportion of children who received co-administered and timely vaccine doses. Co-administration was defined as doses administered on the same day with dates recorded on vaccination cards. Vaccines were considered timely if given within four days before to four weeks after the recommended interval for administration. RESULTS: 10,385 children aged 1-4 years in the Kenyan 2014 DHS dataset had vaccination cards which comprised the study sample. Analysis revealed wide a range for receipt of timely doses, from 90.2% for OPV0 to 56.0% for Measles. Co-administration of the 6-week dose was associated with 2.81 times higher odds of a timely Penta dose 1 (95% CI: 2.28, 3.46) and birth-dose co-administration was associated with a substantial increase in timely BCG vaccination: AOR 7.43 (95% CI: 6.31, 8.75). CONCLUSIONS: Though vaccine coverage in Kenya was high, timely vaccination was markedly low, with resultant implications for population immunity and potential spread of communicable diseases in unvaccinated infants. Co-administration of vaccines, place of residence, wealth index, and child age were consistently related to the odds of timely vaccine receipt. These relationships reinforce the importance of dedicating resources to programs that educate low socio-economic groups about the importance of vaccine co-administration.

Socioeconomic factors associated with full childhood vaccination in Bangladesh, 2014.

OBJECTIVES: Childhood vaccination in Bangladesh has improved, but there is room for improvement. This study estimated full immunization coverage in Bangladeshi children and characterized risk factors for incomplete immunization. METHODS: Using the 2014 Bangladesh Demographic and Health Survey (DHS), full vaccination of children aged 12 to 24 months was examined; this was defined as the receipt of one dose of bacillus Calmette-Guérin (BCG), three doses of pentavalent vaccine, three doses of oral polio vaccine (OPV), and one dose of measles-containing vaccine (MCV). Associations between full vaccination and selected risk factors were assessed by logistic regression. RESULTS: Overall, 83% of children were fully vaccinated. BCG had the highest completion (97%), followed by OPV (92%), pentavalent vaccine (91%), and MCV (85%). Full vaccination coverage ranged from 64.4% in Sylhet to 90.0% in Rangpur and was lowest among non-locals of all regions (78.4%). Children who were in the lowest wealth quintile, who had mothers without antenatal care visits, or who had mothers without autonomy in healthcare decision-making were less likely to be fully vaccinated. CONCLUSIONS: Overall, full vaccination of children is high, but varies by vaccine type. Disparities still exist by wealth and by region. Maternal access to care and autonomy in healthcare decision-making are associated with higher vaccination coverage.

Factors Associated with Vaccination Status of Children Aged 12-48 Months in India, 2012-2013.

Objectives India has more unvaccinated children than any other country despite provision of free vaccines through the government's Universal Immunization Program. In this study, we calculated the proportion of children aged 12-48 months who were fully vaccinated, under-vaccinated, or who had not received any vaccines. Childhood, household, and sociocultural factors associated with under-vaccination and non-vaccination were evaluated. Methods Using data from India's 4th District-level Health and Facility Survey, 2012-2013 (DLHS-4) and the 2012-2013 Annual Health Survey (AHS), we calculated the proportion of children who were non-vaccinated, under-vaccinated, or fully vaccinated with 1 dose of Bacillus Calmette-Guérin, 3 doses of oral polio vaccine, 3 doses of diphtheria-pertussis-tetanus, and 1 dose of measles-containing vaccine. The odds of full vaccination compared to non-vaccination and under-vaccination relative to various factors was assessed using a multivariable, multinomial logistic regression which accounted for survey design. Results Of 1,929,580 children aged 12-48 months, 59% were fully vaccinated, 34% were under-vaccinated, and 7% were non-vaccinated. Compared to children born in government institutions, children delivered in non-institutional settings with a skilled birth attendant present had higher odds of non-vaccination (OR 1.66) and those without a skilled attendant present had still greater odds of non-vaccination (OR 2.39) and under-vaccination (OR 1.11). Conclusions for Practice India's vaccination rates among children aged 12-48 months remains unacceptably low. The Indian government should encourage institutional delivery or birthing with a skilled attendant to ensure women receive adequate health education through antenatal care that includes the importance of childhood vaccination.

Dried blood spots: An evaluation of utility in the field.

BACKGROUND: Use of dried blood spots (DBS) offers advantages over serum samples in studies conducted in resource-poor settings. The aim of this study was to compare the number of adequate spots collected across different demographic groups. METHODS: Five DBS were collected from 3316 individuals aged 0-49 years in Tianjin, China for a measles antibody study; DBS were rated "adequate" or "inadequate." Linear regression, with the number of adequate DBS on a card as the outcome variable, was used to test for predictors of DBS adequacy. RESULTS: There were 0 adequate DBS for 23% of participants and 5 adequate DBS for 24%. Mean number of adequate DBS was 1.68 in infants (<12 months), 2.57 (1-9 years), 3.49 (10-29 years), 3.08 (30-49 years). The number of adequate DBS increased over the study; the mean number of adequate DBS for the five years 2011-2015 were 1.21, 2.52, 3.40, 2.22, and 3.62, respectively. DBS quality was not related to measles IgG antibodies. CONCLUSIONS: DBS are an alternative for adults and children but pose challenges in infants, and improve with experience. In a resource-limited environment or in a scenario where more invasive techniques like venipuncture may be less accepted by the study population, DBS can be the preferred technique to efficiently obtain serum specimens for analyte testing.

Measles Antibodies in Mother-Infant Dyads in Tianjin, China.

Background: Many measles cases in Tianjin, China, occur in infants whose mothers were born after widespread vaccination programs. We assessed age-specific decreases in maternal measles antibodies in infants and examined maternal and infant characteristics in relation to infant antibody titers. Methods: Infant and mother dyads were enrolled from a sample of immunization clinics in all Tianjin districts. Participants' antibody titers were measured from dried blood spots. A multivariable log-linear model regressed infant antibody titers onto infant and mother characteristics. Results: Among 551 infants aged ≤8 months, protective levels of measles antibodies were observed in infants whose mothers had measles titers ≥800 IU/mL (mean antibody titer, 542.5 IU/mL) or 400 to <800 IU/mL (mean, 202.2 IU/mL). Compared with infants whose mothers had no history of disease or vaccination, those with a history of disease had 1.60 times higher titers (95% confidence interval, 1.06-2.43). Conclusions: Limited vaccination programs in the 1980s have resulted in many Chinese women with inadequate protection against measles and an accordingly low efficiency of transplacental transmission to a fetus. Current vaccination programs, which target children aged 8 months through adolescence may be ineffective in controlling transmission of measles to infants.