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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Reactive vaccination campaigns prevented a large measles outbreak, saving thousands of cases in a refugee camp

A large measles outbreak of 1,700 cases occurred in the Rohingya refugee population in Cox’s Bazar, Bangladesh in 2017. In response, two reactive vaccination campaigns delivered the measles and rubella (MR) vaccine to children aged 6 months to 15 years old. This modeling study found that these reactive vaccination campaigns rapidly curbed outbreak transmission, averting an estimated 77,000 measles cases in the refugee camp. This demonstrates that reactive vaccination campaigns can be highly effective in preventing large measles outbreaks in the context of refugee camps, even when prior vaccination rates are low.

Chin T, Buckee CO, Mahmud AS. 2020. Quantifying the success of measles vaccination campaigns in the Rohingya refugee camps. Epidemics. 30.

Mobile health teams in Afghanistan improved immunization coverage in remote and conflict-affected areas, benefiting mothers and children

In Afghanistan, delivering health services through sustained, scheduled mobile health teams in remote and conflict-affected villages improved coverage of maternal and child health interventions, including immunization. The proportion of children under 1 year receiving their first dose of measles vaccine was higher in districts that had received mobile health team services for at least the previous 3 years (73.8%) compared to control districts in the same province (57.3%). The researchers concluded that incorporating mobile clinics into health system infrastructure in a systematic way can effectively improve health for hard to reach mothers and children in remote and conflict-affected areas.

Edmond K, Yousufi K, Naziri M et al.. 2020. Mobile outreach health services for mothers and children in conflict-affected and remote areas: A population-based study from Afghanistan. Archives of Disease in Childhood. 105(1).

Conflict events can disrupt immunization programs and lead to attacks on health workers

This modeling study examined the impact of conflict events on disease control efforts during an Ebola outbreak in the Democratic Republic of the Congo. The model used a timeline of conflict events and an ethnographic appraisal of attacks on health care workers and treatment centers to estimate their impact on the epidemic trajectory of Ebola. Overall, the population-level effectiveness of vaccination was reduced by 43% due to disruptive conflict events. The researchers also found that declining incidence of Ebola was repeatedly reversed by conflict events. This framework can be extended to other diseases and regions experiencing conflict.

Wells CR, Pandey A, Ndeffo Mbah ML et al.. 2019. The exacerbation of Ebola outbreaks by conflict in the Democratic Republic of the Congo. Proceedings of the National Academy of Sciences. 116(48).

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).

The arrival of Syrian refugees in Turkey has caused a rise in infectious diseases, including preventable ones like measles

Forced migration due to the Syrian civil war has led to a re-emergence of several infectious diseases in Turkey, including vaccine-preventable diseases, such as measles (930 cases reported among refugees over 4 years), tuberculosis and hepatitis A.

Doyanay M, Demiraslan H. 2016. Refugees of the Syrian civil war: impact on reemerging infections, health services, and biosecurity in Turkey. Health Security. 14(4).

Wealth did not impact vaccination rates for Somali refugee children in Kenya, suggesting systemic barriers to immunization

In contrast to non-Somalis, family wealth did not significantly affect the likelihood of being fully vaccinated among Somali refugee children living in Kenya. This may point to systemic barriers to vaccination that cut across all socio-economic levels of the Somali refugee population.

Masters NB, Wagner AL, Carlson BF et al.. 2019. Childhood vaccination in Kenya: Socioeconomic determinants and disparities among the Somali ethnic community. International Journal of Public Health. 64(3).

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).

Collapse of primary healthcare during humanitarian emergencies can lead to infectious disease outbreaks in neighboring areas

The humanitarian emergency in Venezuela, and resulting collapse of its primary health care infrastructure, has caused measles and diphtheria to reemerge — disproportionately affecting indigenous populations — and spread to neighboring countries. This sets the stage for the potential reemergence of polio. The re-establishment of measles as an endemic disease in Venezuela (with >5,500 confirmed cases) and its spread to neighboring countries threaten the measles-free status.

Paniz-Mondolfi AE, Tami A, Grillet ME et al.. 2019. Resurgence of vaccine-preventable diseases in Venezuela as a regional public health threat in the Americas. Emerging Infectious Diseases. 25(4).

Universal hepatitis B vaccination for newborns in refugee camps is highly cost-effective

Providing a birth dose of hepatitis B vaccine to all newborns (in addition to routine HepB immunization) was found to be a highly cost-effective means of preventing hepatitis B-related deaths in three refugee populations in Africa which are at extremely high risk of hepatitis B infection. Providing a birth dose only to newborns whose mothers test positive on a rapid diagnostic test was less cost-effective than vaccinating all newborns automatically. Thus, universal hepatitis B vaccination of newborns should remain a priority in refugee camps, despite competing humanitarian needs.

Reardon JM, O'Connor SM, Njau JD et al.. 2019. Cost-effectiveness of birth-dose hepatitis B vaccination among refugee populations in the African region: a series of case studies. Conflict and Health. 13(5).