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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Immunization Terms

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).

Immunization can help reduce the risk of stunting caused by diarrhea in children

A pooled analysis of nine studies assessing the effects of diarrhea on stunting prior to the age of 24 months showed that the odds of stunting were significantly increased with each diarrheal episode. Each day of diarrhea prior to attaining 24 months of age also contributed to the risk of stunting. For each five episodes of diarrhea, the odds of stunting increased by 13%. In addition, once a child becomes stunted, only 6% of those stunted at 6 months of age recovered by 24 months of age.

Checkley, W., Buckley, G., Gilman, R.H., et al.. 2008. Multi-country analysis of the effects of diarrhoea on childhood stunting. International Journal of Epidemiology. 37(4).

Undernutrition is an underlying cause of child deaths associated with diarrhea, malaria, pneumonia, and measles

An analysis of the association between undernutrition and mortality in young children revealed that in 60% of deaths due to diarrhea, 52% of deaths due to pneumonia, 45% of deaths due to measles and 57% of deaths attributable to malaria, undernutrition was a contributing factor.

Caulfield, L.E., de Onis, M., and Black, R.E.. 2004. Undernutrition as an underlying cause of child deaths associated with diarrhea, pneumonia, malaria and measles. American Journal of Clinical Nutrition. 80(1).