Year : 2017 | Volume
: 10 | Issue : 2 | Page : 295--296
Vaccine coverage estimation using Global Positioning System and Google Earth: A commentary
Department of Epidemiology, School of Public Health, University of California, Los Angeles, California, USA
Dr. Ashutosh Sastri Road, Kolkata, West Bengal, India
|How to cite this article:|
Mahapatra T. Vaccine coverage estimation using Global Positioning System and Google Earth: A commentary.Ann Trop Med Public Health 2017;10:295-296
|How to cite this URL:|
Mahapatra T. Vaccine coverage estimation using Global Positioning System and Google Earth: A commentary. Ann Trop Med Public Health [serial online] 2017 [cited 2019 Dec 15 ];10:295-296
Available from: http://www.atmph.org/text.asp?2017/10/2/295/208723
Immunization is one of the most successful and cost-effective public health interventions of the 21st century preventing 2–3 million deaths from common childhood illnesses including diphtheria, pertussis, tetanus, and measles per year. As per the World Health Organization (WHO), the global immunization coverage for Diphtheria-Pertussis-Tetanus (DPT), Polio, Measles, Hepatitis B were 86%, 86%, 85%, and 82%, respectively at the end of 2014. However, the coverage for Haemophilus influenzae type b (Hib) was only 56%.
Despite the significant progress made towards global immunization goals over the last decade, there are wide disparities in immunization coverage across the countries in the world. Limited resources, weak health infrastructure, competing health priorities, and lack of supervision were some of the major contributing factors. Globally, an estimated 18.7 million infants missed out on routine immunization in 2014. Approximately, more than 60% of those unvaccinated children were reported from 10 countries in the world including Democratic Republic of the Congo, Ethiopia, India, Indonesia, Iraq, Nigeria, Pakistan, Philippines, Uganda, and South-Africa. With the aim of improving coverage of Hib and Hepatitis B vaccines, the Pentavalent vaccine was introduced in phased manner in 73 poorest countries across world since 2011. The 'five in one' vaccine protects against five major childhood illnesses (DPT, Hepatitis B, Hib) in a single shot. Yet, many countries are lagging behind in sufficient coverage of routine immunization.
Vaccine coverage has been defined as an estimate of number of people in a population who have been vaccinated in a given time. It helps to monitor the performance of routine vaccination program and effectiveness of ongoing interventions to increase the coverage. There are several methods of assessing this vaccination coverage that included administrative coverage estimate, lot quality assurance sampling, and cluster surveys.
In recent time, designing digital survey by using mobile devices (portable computers, tablets, smartphones) are increasingly used for data collection process. For improving the accuracy of data and provision of location information at low cost, Global Positioning System (GPS) has been employed in various commercial and research applications for spatial mapping using GPS coordinates., This survey tool provided many contextual information such as housing, density of population, and external environment in a defined geographic area. The only available fully functional Global Navigation Satellite System is GPS. At present, there are about 24 GPS satellites that send signals to GPS receivers, which in turn determine the location, direction, and speed of the receiver. Handheld portable GPS receivers are reliable and can be used for storing positional data over time.Furthermore, exact locations of households can be displayed on the map after feeding GPS coordinates into Google Earth software. GPS receiver and Google Earth together may be used for getting geospatial data that represents a relative position of any physical object by numerical values in geographic coordinate system or in a geographical space.
GPS receivers may be used to select and survey households through a multistage cluster sampling design. It will help to estimate what proportions of children have access to immunization service and what proportions of children complete the immunization schedule. It will precisely indicate the variations in coverage levels within specific geographic areas. In vaccination coverage survey methodology, an exact boundary of the enumeration areas is possible by using GPS units in selected clusters. Moreover, it will help to understand whether a selected household is within the right geographic boundary or not. Additionally, time of entry and time of exit of each house can be shown in GPS-enabled mobile phones.
Apart from immunization coverage, this new technology was found to be useful in construction of spot map for cholera outbreak in India pinpointing clustering of cases along the suspected contaminated water source, mapping HIV epidemic in sub-Saharan Africa, and assessing distribution of anemia and nutritional status of 5-10 years children in south India.
Although GPS tracking is a powerful tool and it is being used with great success in research, there are some limitations. One of the major limitations of GPS research is that certain environmental conditions like heavy tree cover; being inside the building, and dense urban location may affect GPS signal and often leads to significant data loss. This new technology solely depends on receiving signals from satellite. Bias may be generated in estimated distance because of changes in atmospheric conditions and local obstructions. In addition, for getting accurate information regarding correct number of buildings and number of buildings in dense areas, latest satellite or aerial photographs are required for most surveys. Other limitations include threat to participant privacy, probability of selection of a non-residential building, maintenance of the portable GPS device (change of battery, recharging overnight), and limited application in developing countries because of poor satellite coverage. Despite such limitations, this satellite-based navigation technology is an important tool in data collection process and interpretation of data points should be done with caution.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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