The Knowledge Hub

What is the Knowledge Hub?

Explore the VoICE Knowledge Hub—a searchable database featuring the latest peer-reviewed research on immunization benefits, especially in low- and middle-income countries. Browse the Knowledge Hub using a variety of different filters to find vaccine evidence based on country, region, topic, or disease. Click on a tag to find more evidence on a specific area, such as the return on investment of vaccines or impacts of infectious disease outbreaks.


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A study in Jordan found that a proactive vaccination campaign has maintained high immunity rates, even with an influx of refugees

The results of a 2016 cross-sectional polio serosurvey found that the Jordan Ministry of Health’s proactive campaign to locate and vaccinate high-risk populations has been successful in maintaining high population immunity — even with a recent influx of refugees from Syria. The study included a community sample of 479 children under 5 years living in areas of Jordan identified as high risk due to being hard-to-reach, having high numbers of refugees, and lower vaccine coverage (under 90%). Polio immunity was found to be over 96% for polio types 1, 2, and 3 even for children living in refugee camps.

Farag NH, Wannemuehler K, Weldon W et al.. 2020. Estimating population immunity to poliovirus in Jordan’s high-risk areas. Human Vaccines & Immunotherapeutics. 16(3).

Investments in polio eradication in Africa improved overall immunization systems and increased coverage of routine vaccinations

A systematic review of 8 African countries that had wild polio virus transmission and significant polio eradication activities found evidence that the huge investments made in polio have strengthened capacity in almost all aspects of the overall immunization systems, especially in the areas of microplanning, service delivery, capacity-building (especially supportive supervision and on-the-job training), and program management. This led to substantial increases in coverage of other routine vaccinations – BCG, DPT, measles – in all 8 countries over a 25-year period (1989-2014), including a more than a 3-fold increase in DPT3 coverage in 2 countries and a more than a 2-fold increase in 3 other countries.

Anya BPM, Moturi E, Aschalew T et al.. 2016. Contribution of polio eradication initiative to strengthening routine immunization: lessons learnt in the WHO African region. Vaccine. 34(43).

Efforts to eradicate polio have also led to improved access to other vaccines

The expertise and assets gained through efforts to eradicate polio at least partially explain the improvement between 2013 and 2015 in vaccination coverage of DPT3 in six out of ten “focus” countries of the Polio Eradication Endgame strategic plan. This includes substantial increases in vaccination rates in India, Nigeria, and Ethiopia, which, combined, reduced the number of children not fully vaccinated with DPT by 2 million in 2 years.

van den Ent MMVX, Mallya A, Sandhu H et al.. 2017. Experiences and lessons from polio eradication in 10 focus countries of the polio endgame strategic plan. Journal of Infectious Diseases. 216(1).

Immunization reduces antibiotic use in children by preventing flu-related illnesses and secondary infections

Several studies have shown a 13-50% reduction in the use of antibiotics by children who have received influenza vaccine compared with unvaccinated controls. This is due to a decline in febrile illnesses causes by influenza — for which antibiotics are often prescribed inappropriately — as well as a decline in secondary bacterial infections requiring antibiotic treatment, such as pneumonia and middle ear infections, that are triggered by influenza.

Klugman KP, Black S. 2018. Impact of existing vaccines in reducing antibiotic resistance: Primary and secondary effects. Proceedings of the National Academy of Sciences. 115(51).

Immunization with pneumococcal conjugate vaccine reduces drug-resistant cases of pneumococcal diseases in children and adults

Studies in several countries have shown that, following the introduction of pneumococcal conjugate vaccine, there was a reduction in the number and percent of drug-resistant cases of pneumococcal diseases in children, and in some countries in adults, due to herd effects. In Japan there was a 10-fold decline in the proportion of penicillin-resistance among cases of invasive pneumococcal disease (from 56% to 5%), and in the U.S. there were reductions of 81% and 49% in the proportion of penicillin-resistant cases in children less than two years and in adults more than 65 years old, respectively.

Klugman KP, Black S. 2018. Impact of existing vaccines in reducing antibiotic resistance: Primary and secondary effects. Proceedings of the National Academy of Sciences. 115(51).

Investment in disease surveillance in areas of conflict can prevent new outbreaks of vaccine-preventable diseases

The development and successful implementation of a coordinated, multi-country plan in response to a wild polio outbreak in Syria and Iraq halted the outbreak within 6 months. The response, which involved strengthening acute flaccid paralysis surveillance and more than 70 synchronized mass polio vaccination campaigns in 8 Middle Eastern countries (reaching >27 million children), could serve as a model for responding to disease outbreaks in areas affected by conflict and political instability.

Mbaeyi C, Ryan MJ, Smith P et al.. 2017. Response to a large polio outbreak in a setting of conflict- Middle East, 2013-2015. Morbidity and Mortality Weekly Report. 66(8).

Armed conflict can lead to outbreaks of polio

An outbreak of wild polio virus began two years after the onset of the civil war in Syria and subsequently spread to Iraq, causing a total of 38 cases (36 in Syria). Factors leading to the outbreak included a decline in polio surveillance and in polio vaccination coverage (from 83% for 3 doses of oral polio vaccine pre-war in Syria to 47-52%).

Mbaeyi C, Ryan MJ, Smith P et al.. 2017. Response to a large polio outbreak in a setting of conflict- Middle East, 2013-2015. Morbidity and Mortality Weekly Report. 66(8).

Mothers with higher education are more likely to vaccinate their children, leading to better immunization rates

A study conducted in Pakistan, designed to explore the association of maternal education and empowerment with childhood polio vaccination, showed that mothers with more education are more likely to vaccinate their children – 74% of children of mothers with higher education were completely vaccinated compared to 67% of those with primary education and only 47% of those with no education.

Khan, M.T., Zaheer, S., Shafique, K.. 2017. Maternal education, empowerment, economic status, and child polio vaccination uptake in Pakistan: a population based cross sectional study. BJM Open. 7(3).

Integrating vitamin A supplementation during vaccine campaigns increased coverage and effectiveness for both interventions

In an effort to reach children with vitamin A deficiency in the African countries of Angola, Chad, Cote d’Ivoire, and Togo, vitamin A supplementation was administered during Polio vaccine campaigns. This led to a minimum coverage of 80% for vitamin A and 84% for polio vaccine in all of the immunization campaigns. During the second year of vitamin A integration into the polio vaccination campaign, coverage exceeded 90% for both vitamin A and polio vaccination in all four countries.

Chebab, E.T., et al.. 2016. Experience of integrating vitamin A supplementation into polio campaigns in the African Region.. Vaccine. 34(43).

Immunizations for DPT, polio, and measles improve children’s growth and overall health

Modeling of data from India’s National Family Health Survey-3 indicated that vaccinations against DPT, polio and measles were significant positive predictors of a child’s height, weight and hemoglobin concentration. This was ascertained post modeling of data obtained from over 25,000 children.

Bhargava, A., Guntupalli, A.M., Lokshin, M.. 2011. Health Care Utilization, socioeconomic factors and child health in India. Journal of Biosocial Sciences. 43(6).