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.


Diseases & Vaccines


WHO Regions


Immunization Terms

Immunization with PCV reduces pneumonia cases and saves lives, easing economic burden on families and health systems

A surveillance study over a 10-year period in the Gambia found that routine introduction of PCV led to a 33% reduction in the incidence of radiological pneumonia and a 27% decline in pneumonia hospitalizations in children. Reducing the rate of pneumococcal disease will not only save lives but will also reduce the substantial economic burden placed on families and health systems.

Mackenzie GA, Hill PC, Jeffries DJ et al.. 2021. Impact of the introduction of pneumococcal conjugate vaccination on invasive pneumococcal disease and pneumonia in The Gambia: 10 years of population-based surveillance. The Lancet Infectious Diseases. 21(9).

Immunizing pregnant women protects infants from influenza, with 56% efficacy in the first 2 months of life

A pooled analysis of three randomized controlled trials conducted in Nepal, Mali, and South Africa between 2011 and 2014 found that immunization during pregnancy provided protection against influenza to young infants from birth through 4 months of age. Protection against infant influenza was greatest in the first 2 months of life, with 56% efficacy, and the pooled efficacy of maternal vaccination to prevent infant laboratory-confirmed influenza up to 6 months of age was 35%.

Omer SB, Clark DR, Madhi SA et al.. 2020. Efficacy, duration of protection, birth outcomes, and infant growth associated with influenza vaccination in pregnancy: a pooled analysis of three randomised controlled trials. The Lancet Respiratory Medicine. 8(6).

Integrating family planning and immunization services in Malawi was found to be feasible and beneficial

In this mixed-methods implementation study, routine immunization and family planning services were integrated across health facilities and community sites across two rural districts in Malawi, Dowa and Ntchisi. The total number of women accessing family planning services during the study period increased by 14% while DPT immunization rates for children remained consistent. In interviews, parents and providers found the integration of family planning and immunization services to be feasible and beneficial, indicating a win-win for both services.

Cooper CM, Wille J, Shire S et al.. 2020. Integrated Family Planning and Immunization Service Delivery at Health Facility and Community Sites in Dowa and Ntchisi Districts of Malawi: A Mixed Methods Process Evaluation. International Journal of Environmental Research and Public Health. 17(12).

Immunization coverage can vary dramatically across regions, with some areas having better access than others

An equity impact analysis of the 2016 Ethiopia Demographic and Health Survey dataset identified significant disparities in full immunization coverage across different regions of Ethiopia among children aged up to 36 months. Children in the Addis Ababa and Dire Dawa regions of Ethiopia were 7 times more likely to have full vaccination coverage compared to children living in the Afar region, a rural region with large numbers of pastoralist nomadic communities.

Geweniger A, Abbas KM. 2020. Childhood vaccination coverage and equity impact in Ethiopia by socioeconomic, geographic, maternal, and child characteristics. Vaccine. 38(20).

Children in female-headed households were less likely to be fully vaccinated compared to male-headed households

An equity impact analysis of the 2016 Ethiopia Demographic and Health Survey dataset for full vaccination coverage among children aged up to 36 months found that children living in female-headed households were 49% less likely to have full vaccination coverage compared to children living in male-headed households.

Geweniger A, Abbas KM. 2020. Childhood vaccination coverage and equity impact in Ethiopia by socioeconomic, geographic, maternal, and child characteristics. Vaccine. 38(20).

Children born in a health facility are more likely to receive full vaccinations compared to those born at home

A study in Ghana using nationally representative survey data found that children born in an institutional setting had a substantially higher proportion of full vaccination (73.9%) compared to those born at home (60.8%). Children born in a health facility—either public or private—had 1.71 times the odds of receiving a full vaccination schedule compared to children born at home.

Moran EB, Wagner AL, Asiedu-Bekoe F et al.. 2020. Socioeconomic characteristics associated with the introduction of new vaccines and full childhood vaccination in Ghana. Vaccine. 38(14).

Immunization can reduce child mortality and enhance the immune system’s ability to fight against other diseases

This 2013 review summarizes data from several randomized trials in which measles and tuberculosis vaccines were associated with a substantial reduction in overall child mortality, which cannot be solely explained by prevention of the target disease. These studies suggest that in addition to disease-specific effects, some live vaccines may also provide “nonspecific effects” that enhance the immune system’s ability to protect against additional pathogens.

Benn CS, Netea MG, Selin LK et al.. 2013. A small jab – a big effect: Nonspecific immunomodulation by vaccines. Trends in Immunology. 34(9).

Administration of vaccines can also decrease childhood deaths from other causes, above and beyond the expected direct impact of the vaccine

Three randomized controlled trials enrolling a total of over 6500 infants over 12 consecutive years in Guinea-Bissau found a 38% reduction in all-cause neonatal mortality associated with early vaccination with BCG. Revisiting these trials to explore the seasonal variation in this effect, it was found that early vaccination with BCG was particularly beneficial when administered between November and January, coincident with peaking malaria infections.

Jensen KJ, Biering-Sørensen S, Ursing J et al. 2020. Seasonal variation in the non-specific effects of BCG vaccination on neonatal mortality: Three randomised controlled trials in Guinea-Bissau. BMJ Global Health. 5(3).

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).

Attending antenatal care visits increases the likelihood of fully immunized children in Nigeria and other countries

Mothers in Nigeria were between 2-4 times more likely to have fully immunized children if they attended 1-3 antenatal care (ANC) visits, between 2.5-8 times more likely if they attended 4-7 ANC visits, and between nearly 3-14 times more likely if they attended at least 8 ANC visits compared to those who had no ANC.

Similar findings have been seen in many LMICs, including Senegal, Bangladesh, Indonesia, India, Zimbabwe, and Southwest Ethiopia.

Anichukwu OI, Asamoah BO. 2019. The impact of maternal health care utilisation on routine immunisation coverage of children in Nigeria: A cross-sectional study. BMJ Open. 9(6).