Immunization coverage and immunity to diphtheria and tetanus among children in Hyderabad, India

Trends in Urban Immunization Coverage in India: A Meta-Analysis and Meta-Regression

OBJECTIVES

To assess the gaps and trends in child immunization coverage among urban and rural areas in India, and compare the success of immunisation program in each.

METHODS

PubMed, Scopus, and Crossref, and Google Scholar electronic databases were searched on October 9, 2019, and March 21, 2020, for studies that measured and reported immunization coverage indicators in India. Random-effects meta-analyses and meta-regressions were conducted.

RESULTS

The authors' search identified 545 studies, and 2 were obtained by expert suggestion. Among these 68 studies and 6 surveys were included. They found that full immunization coverage has grown yearly at 2.65% and 0.82% in rural and urban areas, respectively whereas partial immunization coverage declined by -2.44% and -0.69%, respectively. Percentage of nonimmunized children did not show a statistically significant trend in either.

CONCLUSION

While rural immunization coverage has seen a large increase over the past two decades, the progress in urban areas is weak and negligible. This was largely attributable to a focus on minimizing dropouts in rural areas. However, a lack of significant reduction in unimmunized children may indicate left-out children or pockets in both rural and urban areas. The poor performance of immunization programs in urban areas, coupled with a larger impact of COVID-19, warrants that India urgently adopts urban-sensitive and urban-focused policies and programs.

Immunity against diphtheria among children aged 5-17 years in India, 2017-18: a cross-sectional, population-based serosurvey

BACKGROUND

Diphtheria is re-emerging as a public health problem in several Indian states. Most diphtheria cases are among children older than 5 years. In this study, we aimed to estimate age-specific immunity against diphtheria in children aged 5-17 years in India.

METHODS

We used residual serum samples from a cross-sectional, population-based serosurvey for dengue infection done between June 19, 2017, and April 12, 2018, to estimate the age-group-specific seroprevalence of antibodies to diphtheria in children aged 5-17 years in India. 8309 serum samples collected from 240 clusters (122 urban and 118 rural) in 60 selected districts of 15 Indian states spread across all five geographical regions (north, northeast, east, west, and south) of India were tested for the presence of IgG antibodies against diphtheria toxoid using an ELISA. We considered children with antibody concentrations of 0·1 IU/mL or greater as immune, those with levels less than 0·01 IU/mL as non-immune (and hence susceptible to diphtheria), and those with levels in the range of 0·01 to less than 0·1 IU/mL as partially immune. We calculated the weighted proportion of children who were immune, partially immune, and non-immune, with 95% CIs, for each geographical region by age group, sex, and area of residence (urban vs rural).

FINDINGS

29·7% (95% CI 26·3-33·4) of 8309 children aged 5-17 years were immune to diphtheria, 10·5% (8·6-12·8) were non-immune, and 59·8% (56·3-63·1) were partially immune. The proportion of children aged 5-17 years who were non-immune to diphtheria ranged from 6·0% (4·2-8·3) in the south to 16·8% (11·2-24·4) in the northeast. Overall, 9·9% (7·7-12·5) of children residing in rural areas and 13·1% (10·2-16·6) residing in urban areas were non-immune to diphtheria. A higher proportion of girls than boys were non-immune to diphtheria in the northern (17·7% [12·6-24·2] vs 7·1% [4·1-11·9]; p=0·0007) and northeastern regions (20·0% [12·9-29·8] vs 12·9% [8·6-19·0]; p=0·0035).

INTERPRETATION

The findings of our serosurvey indicate that a substantial proportion of children aged 5-17 years were non-immune or partially immune to diphtheria. Transmission of diphtheria is likely to continue in India until the immunity gap is bridged through adequate coverage of primary and booster doses of diphtheria vaccine.

FUNDING

Indian Council of Medical Research.

Epidemiology of Diphtheria in India, 1996-2016: Implications for Prevention and Control

Diphtheria is an acute disease caused by exotoxin-producing Corynebacterium diphtheriae. Globally, diphtheria has been showing a declining trend due to effective childhood vaccination programs. A substantial proportion of global burden of diphtheria is contributed by India. Hospital-based surveillance studies as well as diphtheria outbreaks published in last 20 years (1996-2016) indicate that diphtheria cases are frequent among school-going children and adolescents. In some Indian states, Muslim children are affected more. As per the national level health surveys, coverage of three doses of diphtheria vaccine was 80% during 2015-2016. Information about coverage of diphtheria boosters is not routinely collected through these surveys, but is expected to be low. Few studies also indicate low diphtheria immunity among school-going children and adults. The strategies for prevention of diphtheria need to focus on improving coverage of primary and booster doses of diphtheria vaccines administered as a part of Universal Immunization Program as well as introducing diphtheria vaccine for school-going children.

A Case-control Study of Diphtheria in the High Incidence City of Hyderabad, India

BACKGROUND

India accounts for approximately 72% of reported diphtheria cases globally, the majority of which occur in the state of Andhra Pradesh. The aim of this study is to better understand lack of knowledge on diphtheria vaccination and to determine factors associated with diphtheria and low knowledge and negative attitudes.

METHODS

We performed a 1:1 case-control study of hospitalized diphtheria cases in Hyderabad. Eligible case patients were 10 years of age or older, resided within the city of Hyderabad and were diagnosed with diphtheria per the case definition. Patients admitted to the hospital for nonrespiratory communicable diseases and residing in the same geographic region as that of cases were eligible for enrolment as controls

RESULTS

: There were no statistical differences in disease outcome by gender, education, economic status and mean room per person sleeping in the house in case and control subjects. Not having heard of diphtheria (adjusted odds ratio: 3.56; 95% confidence intervals: 1.58-8.04] and not believing that vaccines can prevent people from getting diseases (adjusted odds ratio: 3.99; 95% confidence intervals: 1.18-13.45) remained significantly associated with diphtheria on multivariate analysis.

CONCLUSION

To reduce the burden of diphtheria in India, further efforts to educate the public about diphtheria should be considered.

Strategies for Coordination of a Serosurvey in Parallel with an Immunization Coverage Survey

A community-based immunization coverage survey is the standard way to estimate effective vaccination delivery to a target population in a region. Accompanying serosurveys can provide objective measures of protective immunity against vaccine-preventable diseases but pose considerable challenges with respect to specimen collection and preservation and community compliance. We performed serosurveys coupled to immunization coverage surveys in three administrative districts (woredas) in rural Ethiopia. Critical to the success of this effort were serosurvey equipment and supplies, team composition, and tight coordination with the coverage survey. Application of these techniques to future studies may foster more widespread use of serosurveys to derive more objective assessments of vaccine-derived seroprotection and monitor and compare the performance of immunization services in different districts of a country.

Diphtheria Re-emergence: Problems Faced by Developing Countries

In the pre-vaccination era, diphtheria was a leading cause of childhood mortality. With the introduction of routine childhood immunization, paediatric care and improved hygiene status the disease has been almost completely eradicated in many developed countries. On the contrary developing countries, still account for 80-90% of the global burden. Retrospective analysis of 52 cases of diphtheria over a period of 12 years at a tertiary referral hospital was carried out. They were analyzed for mortality and morbidity trends, immunization status, microbiological confirmation rates and antidiphtheritic serum (ADS) administration. Incidence in those over 5 years was 59.61%. Only 11.54% cases were either partially or fully immunized. The case fatality rate was 36.53%. Culture was performed only in 17 cases whereas ADS was administered in only 16 cases. In conclusion, the occurrence of diphtheria even in those immunized highlights the flaws in the present immunization program. Poor immunization coverage, lack of ADS, antibiotic resistance are the main reasons for re-emergence of diphtheria.