Summary – Page 11 – VoICE (2024)

In Argentina, more than 50% of deaths due to pertussis occurred in infants younger than 2 months of age — too young to be vaccinated in the country. The impact of maternal pertussis vaccination in protecting their infants against the disease reduced the incidence of pertussis in infants less than 2 months old by half, when comparing states with high and low maternal vaccination rates.

Despite the introduction of pneumococcal conjugate vaccine (PCV) in the childhood immunization program in New Zealand, the incidence of invasive pneumococcal disease in neonates (<30 days old) remains relatively high at 6 per 100,000 (versus 2/100,000 in the U.S.). Out of 19 cases in infants <30 days old in this study, 9 (47%) occurred during the first 7 days of life and 6 within the first 48 hours. If proven effective, maternal vaccination would cover 74% to 84% of the serotypes that infected these infants, depending on the vaccine.

Vaccinating pregnant women against pertussis at least one week before delivery was found to be 91% effective in preventing the disease in infants <3 months old and 95% effective in preventing infant deaths in a study conducted in England over a 3-year period following the introduction of dTap-IPV vaccine for pregnant women. Of the 37 deaths from pertussis in infants that occurred in England from 2009 to 2015, 32 (86%) were in infants <2 months of age, highlighting the vulnerability of very young infants to severe pertussis. All but 2 of the deaths in <2 month olds were in children whose mothers hadn’t been vaccinated against pertussis during their pregnancy, while in the 2 other cases, the vaccination occurred too late in the pregnancy (<10 days before the birth).

Pregnant women are at particularly high risk of serious illness and death from a variety of bacterial and viral diseases, such as influenza, pneumococcal pneumonia, and Group B strep, for which vaccines exist or are in development. Vaccine-preventable diseases in pregnancy are associated with adverse pregnancy outcomes such as spontaneous abortion, congenital anomalies, preterm birth, and low birth weight.

The period following delivery but before an infant acquires immunity to diseases by natural exposure or immunization — is when infant mortality from infections is highest. Vaccinating pregnant women has shown to be effective in protecting young infants against influenza and pertussis.

Infants less than 2 months old are too young to be vaccinated against pertussis yet are at highest risk of severe disease – – a 75% hospitalization rate and a 1% case fatality rate. A case-control study in six U.S. states found that vaccinating women during the third trimester of pregnancy with Tdap vaccine provided 81% protection against pertussis to infants <2 months and 91% protection against hospitalized cases of pertussis.

Use of recommended maternal health care services — defined as at least 4 antenatal care visits, having a skilled attendant at birth, and delivery in a health facility — was a predictor of timely vaccination of mothers’ infants in a study conducted in Ghana. Compared to children whose mothers received one or two of these services, infants born to mothers who received all three interventions were roughly 30% more likely to be fully vaccinated by 12-23 months of age, while children whose mothers received none of these services were only about half as likely to be fully vaccinated. Investing in maternal health, which creates familiarity with the health system and increases mothers’ knowledge about disease prevention, can improve the health of both the mother and her children beyond infancy.

Children in Shanghai, China whose families migrated from rural areas — now roughly 40% of the city’s total population — are half as likely as “local” children to receive the first dose of measles vaccine by 9 months of age and 42% less likely to receive the second measles dose by 24 months. The lower rates of timely first dose measles vaccination among rural migrants vs. local children — 78% vs. 89% – – are a key obstacle to measles elimination in China. This indicates a need to specifically target non-local children for vaccination, especially those living in primarily migrant communities.