Epidemiology: Measles Vaccination Coverage in Africa

Amartya Sen described human development as the removal of unfreedoms and obtaining freedoms which give people access to different opportunities. The social freedoms are those which allow people to live higher quality lives, such as education and healthcare. Vaccinations are an important part of healthcare and not everyone has access to them due to failing healthcare systems and a lack of access to resources. The measles is a disease which can protected against by a vaccination, but people in Africa especially have decreased access to it due to their location or the cost of the vaccines. It is a human right to receive adequate healthcare and finding ways to distribute the measles vaccine to everyone in Africa is one step closer to advancing human development.

Measles is a contagious viral disease that has been preventable through vaccination since 1963. There are two doses to the vaccine to provide optimal protection. One dose is approximately 85-90% efficient when given at nine months old, and the second dose efficiency is greater than 99% when given at twelve months old or later (Goodson, 2011). If people are to get measles, it is usually contracted by young children. Childbearing mothers and children are hit hardest by the disease (Wesolowski, 2016). Once naturally infected, however, the person will have lifelong immunity. The vaccine for measles is combined with the vaccines for other diseases, to prevent multiple in one shot. The most common forms of the vaccine are measles-rubella (MR) or measles-mumps-rubella (MMR). It is relatively inexpensive and is efficient in preventing the diseases (Wesolowski, 2016). Because of the effectiveness and cost of the vaccine, it is easy to distribute and required in routine vaccination plans. It makes sense that everyone around the world should have access to it because it eliminates the threat of a disease that is easily contracted and spread and that kills many people.

The measles vaccine is capable of eliminating the disease if the world reaches herd immunity, which requires between 90-95% of the population to be vaccinated. However due to weak healthcare systems and not fully putting the strategies into practice to give everyone both doses, some countries have fallen behind and their populations continue to be affected by the virus. Within countries and overtime, coverage can vary substantially. Some areas in Africa had less than 80% of the population receive the first dose of the vaccine (Cutts, 2021). Measles is a virus that is spread through direct contact with an infected individual. Therefore, if there are patches of unvaccinated individuals living near each other, the rate of it spreading greatly increases (Takahashi, 2017). Vaccines require the majority of the population in an area to be vaccinated and protected from the disease, and the number of unvaccinated people need to be distributed evenly throughout the population.

The measles vaccine is distributed by national health authorities and nongovernmental organizations, such as UNICEF. Many areas in Africa have lacked vaccination coverage since it has been created. Sub-Saharan Africa is one region where the majority of the world’s remaining measles burden is found, and they have experienced several largescale outbreaks (Verguet, 2012). In Madagascar, the population was split up into twenty-two regions, and the routine vaccination coverage average was 77% (Wesolowski, 2016). Nigeria’s national vaccination coverage over the past twenty years has been greater than 50% (Utazi, 2020). 95% vaccination coverage is ideal for herd immunity. These numbers from several regions in Africa are extremely low in efforts to eliminate the spread of measles.

There are two major systems used to distribute vaccines, routine immunization and supplemental immunization activities (SIA). The routine immunizations, the same system used in America, target children around nine months to receive the first dose, and the SIAs distribute the second dose (Takahashi, 2017). Usually, the regions are split up into zones to allow national health authorities and other organizations to make sure the vaccine is distributed to everyone. Additional targeted campaigns, such as the SIAs, can make a big difference to immunization service delivery, especially in areas with poor routine immunization coverage.

The study on Sub-Saharan Africa studied the demographics and spatial distribution of vaccination in children under five in different countries in Africa (Takahashi, 2017). Weak vaccination systems resulted in small pockets of the population not being vaccinated. It found that there are greater chances for more cold spots, areas of unvaccinated population, in areas with higher populations. Spatially heterogenous vaccination was recognized, causing policy makers to shift the focus from setting country-level targets for coverage to ensure uniformly high vaccination levels across countries to decrease the effect of the unvaccinated pockets.

In Nigeria, one study used geolocated household survey data and covariate information to create maps of vaccination coverage (Utazi, 2020). This form of data collection allows conclusions to be drawn about where there are fewer resources or less access to resources, which result in cold spots. Nigeria had several SIAs introduced to target children ages nine months to fourteen years and another one targeting age nine to fifty-nine months (Utazi, 2020). Because the outbreaks never ceased, the performance of routine immunizations and SIAs needed to be accessed and improved. The vaccination maps created showed significant heterogeneities in the spatial distribution of coverage before and during SIA. These maps were then used to predict the probability of certain areas achieving 95% coverage and to find the areas with the lowest coverage.

In Madagascar, vaccine distribution was studied using geospatial techniques to determine the accessibility and travel time between locations. Madagascar was divided into twenty-two regions to make distribution of vaccinations and vaccination records more efficient and simpler. Because Madagascar is an island, it faces the struggle of having isolated populations and remote areas (Wesolowski, 2016). This can make it harder to administer the vaccinations, but it also creates less opportunity for the disease to spread from one area to another. When looking at the distribution of populations, it is important to take into account how the disease spreads and how accessible vaccines will be to everyone.

One last study of fifteen west African countries used a retrospective multi-country series analysis of national immunization coverage and case surveillance data from 2001 to 2019. It tracked progress in the coverage of measles vaccines, SIAs, and the incidence rates. Using this data, progress towards measles elimination was estimated. The average regional first dose vaccine coverage was 45% in 2001 but rose to 66% in 2019. 73% of these west African countries had introduced the second dose by 2019, but around 4.5 million children still had not received their first dose, 71% of them being from Nigeria (Wariri, 2021). As a result, twelve of the countries are off track to achieve the measles elimination milestones.

This system of routine immunization and SIAs in theory sounds comprehensive and would make sure everyone gets vaccinated, but there are many limiting factors that cause vaccination rates to be below standards. There has been a resurgence of measles due to weak routine vaccination systems and low-quality SIAs. This lack of access to quality healthcare allows the virus to infect the special clusters of unvaccinated children in populations. Demography, vaccine access, and human connectivity play a major role in vaccine coverage. In studying the demographics and special distribution of vaccination in children under five in different countries in Africa, the hope is to identify the cold spots of the lack of vaccination and create vaccination policy that will be the most effective in the regions (Takahashi, 2017). Another reason these plans do not work in certain areas in Africa is due to location. Some districts are weakly connected, or remote, making it hard to distribute resources to these communities because there are very few trips to the remote areas. Low coverage districts and a large proportion of unvaccinated children live in conflict-affected areas with remote rural areas and some urban areas (Cutts, 2021). Remoteness, conflict, and urban slums pose problems and contribute to the inequality of the clusters of unvaccinated people. Socio-economic and cultural factors also have an effect on people’s willingness to trust the vaccine and get it. A study from the University of Southampton found that poor access to health services, poor education, low stock of vaccines, and even vaccine refusal led to low vaccination levels (University, 2019).

In order for measles reduction to continue increasing worldwide, routine immunization needs to become more equal and efficient and SIAs need to become more effective. Vaccination services need to target the most vulnerable populations, areas, and demographics to fill the gaps and reduce the amounts of clusters of unvaccinated people. Resources need to be readily and rapidly available for those in rural areas and areas of conflict, two of the most at risk populations (Cutts, 2021). Data science continues to be an asset to breaking down the barriers in vaccination coverage. It uses demographic information and provides maps, geospatial data, and spatial distribution to clearly mark the areas most in need of support and more efficient immunization systems and SIAs. These techniques show the progression of the measles immunization process and how far this development has come already. They also provide insight into how to get the entire populations immunized and not certain areas in order to reach herd immunity and eliminate outbreaks of the disease. Equality and accessibility to health care is crucial to end measles outbreaks. The organizations giving out the resources need to become stronger and more prepared to help distribute the vaccine when it is needed.

There has been sufficient data about different regions in Africa that are struggling to meet herd immunity for the measles immunization, causing large outbreaks. However, there is a gap in the literature about the parts of Africa that have a high immunization rate, and the methods these areas used to obtain this. Different organizations, both national health authorities and nongovernmental organizations, are working to distribute vaccinations to all regions and reach all populations, but sometimes they are unable to successfully reach everyone. There are many factors as to why the systems that worked in the United States and other developed countries are not working, and some are the location and conflict which hinder people from obtaining vaccines. The coverage rates for other areas around the world with low vaccination rate are missing as well. Despite this, there should be solutions to getting everyone vaccinated. Money and resources should not be the issue because healthcare is a basic necessity and people in Africa should not be dying from a disease that is easily treatable. Data science has helped to determine where vaccination coverage is low and where it is better, and some reasons why vaccinations are hard to obtain, but more information is needed on how these problems are being fixed.

Central research question: The two part system of routine vaccination and SIAs has worked successfully in some countries, more developed, to obtain high vaccination rates, but what are some other systems or ways to alter this system to make it more compatible to regions with different demographics or economic situations?

Bibliography

Cutts, F. T., Ferrari, M. J., Krause, L. K., Tatem, A. J., & Mosser, J. F. (2021, January 5). Vaccination strategies for measles control and elimination: Time to strengthen local initiatives. BMC Medicine. Retrieved October 4, 2021, from https://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-020-01843-z.

Goodson, J. L., Masresha, B. G., Wannemuehler, K., Uzicanin, A., & Cochi, S. (2011). Changing epidemiology of measles in Africa. The Journal of infectious diseases, 204 Suppl 1, S205–S214. https://doi.org/10.1093/infdis/jir129

Takahashi, S., Metcalf, C. J. E., Ferrari, M. J., Tatem, A. J., & Lessler, J. (2017, May 25). The geography of measles vaccination in the African Great Lakes Region. Nature News. Retrieved October 4, 2021, from https://www.nature.com/articles/ncomms15585.

University of Southampton. (2019, April 11). Child vaccination levels falling short in large parts of Africa. ScienceDaily. Retrieved October 24, 2021, from https://www.sciencedaily.com/releases/2019/04/190411101738.htm.

Utazi, C. E., Wagai, J., Pannell, O., Cutts, F. T., Rhoda, D. A., Ferrari, M. J., Dieng, B., Oteri, J., Danovaro-Holliday, M. C., Adeniran, A., & Tatem, A. J. (2020, February 29). Geospatial variation in measles vaccine coverage through routine and campaign strategies in Nigeria: Analysis of recent household surveys. Vaccine. Retrieved October 4, 2021, from https://www.sciencedirect.com/science/article/pii/S0264410X20303017?via%3Dihub.

Verguet S, Jassat W, Hedberg C, Tollman S, Jamison DT, Hofman KJ. Measles control in Sub-Saharan Africa: South Africa as a case study. Vaccine. 2012 Feb 21;30(9):1594-600. doi: 10.1016/j.vaccine.2011.12.123. Epub 2012 Jan 9. PMID: 22230581.

Wariri, O., Erondu, N. A., Nkereuwem, E., Edem, B., Nkereuwem, O., Idoko, O. T. (2021, March 1). A scorecard of progress towards measles elimination in 15 west African countries. The Lancet Global Health. Retrieved October 24, 2021, from https://www.thelancet.com/journals/langlo/article/PIIS2214-109X(20)30481-2/fulltext.

Wesolowski, A., Mensah, K., Brook, C. E., Andrianjafimasy, M., Winter, A., Buckee, C. O., Razafindratsimandresy, R., Tatem, A. J., Heraud, J.-M., Metcalf, C. J. E., & Al., E. (2016, April 1). Introduction of rubella-containing-vaccine to madagascar: Implications for roll-out and local elimination. Journal of The Royal Society Interface. Retrieved October 4, 2021, from https://royalsocietypublishing.org/doi/full/10.1098/rsif.2015.1101?etoc=.