The Knowledge Hub

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 during pregnancy reduces the risk of miscarriages, stillbirths, low birthweight, and premature deliveries

Studies from multiple Western countries have found that pregnant women infected with influenza during the 2009 A/H1N1 pandemic were at higher risk of miscarriages, stillbirths, low birthweight and premature deliveries. The risk of fetal death was between 2 and 5.5 times higher in pregnant women with influenza than in pregnant women without influenza. In the UK, the rate of stillbirths was 4.5 times higher and the likelihood of preterm delivery was 4 times greater in influenza-infected pregnant women than non-infected women.

Although this article indicated that influenza vaccination is safely used for the mother and the fetus, conflicting data exists on the effect of vaccination in improving preterm birth rates.

Nunes MC, Madhi SA. 2015. Review on the effects of influenza vaccination during pregnancy on preterm births. Human Vaccines & Immunotherapeutics. 11(11).

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).

Empowering women can lead to greater vaccination rates in children

In a systematic review of qualitative research from low- and middle-income countries, women’s low social status was shown to be a barrier to their children accessing vaccinations. Specific barriers included access to education, income, resource allocation, and autonomous decision-making related to time. The authors suggest that expanding the responsibility for children’s health to both parents (mothers and fathers) may be one important element in removing persistent barriers to immunization often faced by mothers.

Merten, S., Hilber, A.H., Biaggi, C., et al.. 2015. Gender Determinants of Vaccination Status in Children: Evidence from a Meta-Ethnographic Systematic Review.. PloS ONE. 10(8).

Vaccination provides additional protection for children who are HIV positive, protecting them from preventable infections

A review of evidence for the use of pneumococcal conjugate vaccine in South Africa showed that children who are HIV positive are at significantly increased risk of pneumococcal disease, and so will benefit the most from vaccination, despite decreased vaccine efficacy in this group compared to healthy children.

Zar, H.J. and Madhi, S.A.. 2008. Pneumococcal conjugate vaccine – a health priority. South African Medical Journal. 98(6).

The pneumococcal conjugate vaccine was associated with a decline in antibiotic-resistant pneumococcal cases in South Africa

This study from South Africa demonstrates significant declines in invasive pneumococcal disease cases caused by bacteria that are resistant to one or more antibiotics. In fact, the rate of infections resistant to two different antibiotics declined nearly twice as much as infections that could be treated with antibiotics.

Von Gottberg, A., de Gouveia, L., Tempia, S., et al.. 2014. Effects of pneumococcal vaccine in invasive pneumococcal disease in South Africa. New England Journal of Medicine. 371(20).

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).

Pediatric pneumococcal or Hib meningitis surviviors had a higher likelihood for neuropsychological deficits

In a systematic literature review of studies in Africa, it was found that 25% of children who survived pneumococcal or Hib meningitis had neuropsychological deficits.

Ramakrishnan, M., Ulland, A.J., Steinhardt, L.C., et al. 2009. Sequelae due to bacterial meningitis among African children: a systematic literature review. BMC Medicine. 7(47).

Bacterial meningitis is associated with long-term neurophysiological impacts

A systematic literature review analyzing data from 21 African countries revealed that bacterial meningitis is associated with high case fatality and frequent neurophysiological sequelae. Pneumococcal and Hib meningitis contribute to one third of disease related mortality. They also cause clinically evident sequalae in 25% of survivors prior to hospital discharge. The three main causes of bacterial meningitis- Haemophilus influenzae type B; Streptococcus pneumoniae (pneumococcus) and Neisseria meningitidis (meningococcus) are vaccine preventable, routine use of conjugate vaccines have potential for significant health and economic benefits.

Neuropsychological sequelae includes hearing loss, vision loss, cognitive delay, speech/language disorder, behavioural problems, motor delays/impairment, and seizures.

Ramakrishnan, M., Ulland, A.J., Steinhardt, L.C., et al. 2009. Sequelae due to bacterial meningitis among African children: a systematic literature review. BMC Medicine. 7(47).