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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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).

Immunization rates are low among pregnant adolescents in rural areas with less education and lower wealth

The use of antenatal care (ANC) services among pregnant adolescents in low- and middle-income countries, including tetanus toxoid vaccination, was lowest among women who lived in rural areas, had completed less education, and who were of poorer wealth quintiles.

Banke-Thomas OE, Banke-Thomas AO, Ameh CA. 2017. Factors influencing ultilisation of maternal health services by adolescent mothers in Low- and middle-income countries: a systematic review. BMC Pregnancy Childbirth. 17(1).

Influenza vaccination during pregnancy reduces severe pneumonia rates in infants, especially during peak influenza circulation

An analysis of data from three studies showed that the rates of severe pneumonia in infants in their first six months of life was 20% lower overall in infants whose mothers received the influenza vaccination during pregnancy than in infants whose mothers had not, and the rates of severe pneumonia was 56% lower during periods when influenza circulation was highest. These findings correspond with evidence that influenza infection predisposes individuals to pneumococcal infection.

The incidence rate of severe pneumonia in the vaccine group compared to the control group was 43% lower in South Africa, 31% lower in Nepal, but not significantly different in Mali.

Omer SB, Clark DR, Aqil AR et al.. 2018. Maternal influenza immunization and prevention of severe clinical pneumonia in young infants: Analysis of randomized controlled trials conducted in Nepal, Mali and South Africa. Pediatric Infectious Disease Journal. 37(5).

The empowerment of women is associated with higher odds of childhood vaccinations

A systematic review of studies from countries in Africa and Southeast Asia investigated the relationship between a woman’s “agency” (defined as the woman’s ability to state her goals and to act upon them with motivation and purpose) and childhood immunizations in lower-income settings. The review found a general pattern among studies in which higher agency among mothers was associated with higher odds of childhood immunizations. Empowering women in these settings shows promise as a means to improve child health.

Thorpe, S., VanderEnde, K., Peters, C., et al.. 2016. The influence of women’s empowerment on child immunisation coverage in low, lower-middle, and upper-middle income countries: a systematic review of the literature.. Maternal and Child Health Journal. 20(1).

Diarrhea is associated with pneumonia in undernourished children

In a recent review of data from developing countries, researchers found that episodes of diarrhea may predispose undernourished children to pneumonia.

Schlaudecker, E.P., Steinhoff, M.C. and Moore, S.R.. 2011. Interactions of diarrhea, pneumonia, and malnutrition in childhood: recent evidence from developing countries. Current Opinion in Infectious Diseases. 24(5).

Undernourished children have a higher likelihood for diarrhea and pneumonia but immunization can improve infant growth

Multiple studies show that

  1. Diarrhea and pneumonia impair children’s growth and that underlying malnutrition is a major risk factor for these conditions.
  2. “Episodes of diarrhea may predispose to pneumonia in undernourished children” and
  3. Immunization against influenza (in mothers) and Streptococcus pneumoniae may improve infant growth. In addition, new studies from Bangladesh, Colombia, Ghana, and Israel further support the paradigm that malnutrition is a key risk factor for diarrhea and pneumonia.

Schlaudecker, E.P., Steinhoff, M.C. and Moore, S.R.. 2011. Interactions of diarrhea, pneumonia, and malnutrition in childhood: recent evidence from developing countries. Current Opinion in Infectious Diseases. 24(5).

Vaccines are most cost-effective in low income countries

An analysis of the impact of rotavirus vaccine in 25 countries found that the rates of vaccination in all countries were highest and risk mortality lowest in the top two wealth quintile’s coverage. Countries differed in the relative inequities in these two underlying variables. Cost per DALYs averted in substantially greater in the higher quintiles. In all countries, the greatest potential vaccine benefit was in the poorest quintiles; however, reduced vaccination coverage lowered the projected vaccine benefit.

Rheingans, R., Atherly, D., and Anderson, J.. 2012. Distributional impact of rotavirus vaccination in 25 GAVI countries: Estimating disparities in benefits and cost-effectiveness. Vaccine. 30(1).

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).