|LETTER TO THE EDITOR
|Year : 2015 | Volume
| Issue : 3 | Page : 232-233
Target intervention to increase measles vaccination coverage by identifying low-coverage areas using lot quality assurance sampling, Chennai, India, 2012
Tony Fredrick1, Manoj V Murhekar2, Yuvaraj Jayaraman3, Manickam Ponniah4, Kamaraj Pattabi5, Joseph K David4
1 MPH Scholar, National Institute of Epidemiology (ICMR), Chennai, Tamil Nadu, India
2 Scientist F, National Institute of Epidemiology (ICMR), Chennai, Tamil Nadu, India
3 Scientist E, National Institute of Epidemiology (ICMR), Chennai, Tamil Nadu, India
4 Scientist C, National Institute of Epidemiology (ICMR), Chennai, Tamil Nadu, India
5 Technical Assistant (Research-Statistics), National Institute of Epidemiology (ICMR), Chennai, Tamil Nadu, India
|Date of Web Publication||7-Sep-2015|
Scientist E, National Institute of Epidemiology (ICMR), TNHB, Ayapakkam, Chennai - 600 077, Tamil Nadu
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Fredrick T, Murhekar MV, Jayaraman Y, Ponniah M, Pattabi K, David JK. Target intervention to increase measles vaccination coverage by identifying low-coverage areas using lot quality assurance sampling, Chennai, India, 2012. Indian J Public Health 2015;59:232-3
|How to cite this URL:|
Fredrick T, Murhekar MV, Jayaraman Y, Ponniah M, Pattabi K, David JK. Target intervention to increase measles vaccination coverage by identifying low-coverage areas using lot quality assurance sampling, Chennai, India, 2012. Indian J Public Health [serial online] 2015 [cited 2020 Jan 19];59:232-3. Available from: http://www.ijph.in/text.asp?2015/59/3/232/164669
Chennai in South India has been reporting measles vaccination coverage above 95% since 2006. The coverage by areas was heterogeneous. The city reported sporadic cases and outbreaks of measles during 2009-2011. In this context, we conducted a survey in one administrative area to estimate measles vaccination coverage among children aged 12-23 months and to identify health posts with less than 85% coverage and reasons for nonvaccination.
The study area comprised 10 urban health posts, with each serving a population of 100,000 consisting mainly of the slum population. Using lot quality assurance sampling (LQAS),  we required a lot with 37 children ("n0") and a decision of two as the maximum allowed for not vaccinated for measles ("d"). Based on the global goal for measles vaccination coverage,  we assumed 85% coverage for null hypothesis ( H0 ) and >85% for alternative hypothesis. 
In this study, about 51% of the children were males and 70% belonged to low socioeconomic group. Four of the 10 health posts had a coverage of <85%. Only 27% (95% CI: 23-33) of the children had received second dose of measles vaccination. Nearly 6% of the children had delayed vaccination (95% CI: 4-9) and 9% were vaccinated but not as per the immunization schedule, hence were not considered fully vaccinated. The median spacing was more than 35 days. Inadequate measles vaccination coverage was due to increased vaccine spacing and nonvaccination of the migrant children. The major cause of delayed vaccination ( n = 150) was due to childhood illness, 50% due to lower respiratory tract infection, 30% due to diarrhea, and 20% due to fever and birth complications.
We were able to identify the pockets with low coverage of measles vaccination and the vaccination was not as per the recommended schedule and spacing. These findings could have influenced antibody response and optimal protection.  In the study area, measles vaccination coverage was 92%, with vaccine efficacy at 85%. This means that 75% of the children are truly protected, therefore leaving a pool of 25% susceptible for infection and sustain transmission.  We observed low immunization coverage among those who received vaccination from private facilities and children of the migrant population. Those who had received immunization from private sector could not be tracked because there was no registration of details of such children. Majority of the migrants were in contact with health services until the age of 2 months of the child. However, their coverage falls noticeably, suggesting the need for more efforts to retain them in the immunization program.  Absence of the list of children by households was one of our limitations. However, as the children of each of the lot had the same health care opportunity, the sampling unit drawn from only a few persons will be indicative of the entire lot. Second, we anticipated recall bias for vaccination status by parents and minimized the same by data verification.
We recommended organizing mobile immunization camps in low-coverage pockets to vaccinate all the dropouts, reorienting the health workers about importance of tracking the dropouts and those received vaccinations from private sector, and developing services specifically for the migrant communities.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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|[Pubmed] | [DOI]|