Maternal Influenza Vaccination and Effect on Influenza Virus Infection in Young Infants

Abstract

Objective:To assess the effect of seasonal influenza vaccination during pregnancy on laboratory-confirmed influenza in infants to 6 months of age.Design: Nonrandomized, prospective, observational cohort study.Setting: Navajo and White Mountain Apache Indian reservations, including 6 hospitals on the Navajo reservation and 1 on the White Mountain Apache reservation.Participants: A total of 1169 mother-infant pairs with mothers who delivered an infant during 1 of 3 influenza seasons.Main Exposure: Maternal seasonal influenza vaccination. Main Outcome Measures:In infants, laboratoryconfirmed influenza, influenzalike illness (ILI), ILI hospitalization, and influenza hemagglutinin inhibition antibody titers.Results: A total of 1160 mother-infant pairs had serum collected and were included in the analysis. Among infants, 193 (17%) had an ILI hospitalization, 412 (36%) had only an ILI outpatient visit, and 555 (48%) had no ILI episodes. The ILI incidence rate was 7.2 and 6.7 per 1000 person-days for infants born to unvaccinated and vaccinated women, respectively. There was a 41% reduction in the risk of laboratory-confirmed influenza virus infection (relative risk, 0.59; 95% confidence interval, 0.37-0.93) and a 39% reduction in the risk of ILI hospitalization (relative risk, 0.61; 95% confidence interval, 0.45-0.84) for infants born to influenzavaccinated women compared with infants born to unvaccinated mothers. Infants born to influenzavaccinated women had significantly higher hemagglutinin inhibition antibody titers at birth and at 2 to 3 months of age than infants of unvaccinated mothers for all 8 influenza virus strains investigated.Conclusions: Maternal influenza vaccination was significantly associated with reduced risk of influenza virus infection and hospitalization for an ILI up to 6 months of age and increased influenza antibody titers in infants through 2 to 3 months of age.

Indirect evidence that maternal microchimerism in cord blood mediates a graft-versus-leukemia effect in cord blood transplantation

“…This concept is not new. We have known for decades that maternal antibodies protect the child against bacterial infections during the first months of life, and recent influenza vaccination during pregnancy provided evidence that maternal T-cells also protect the newborn against influenza (34). Thus, it is not too farfetched to suggest that maternal anti-IPA immunity might also have a protective effect against cancer in the offspring, as has been suggested by others (35,36).…”

Infection Prevention and Control Guideline for Cystic Fibrosis: 2013 Update

“…466 For example, women immunized against influenza during pregnancy had fewer respiratory tract illnesses in the 6 months after delivery, and their infants had fewer febrile illnesses. 467,468 There are also guidelines for vaccination of people who are immunocompromised that are applicable to individuals with CF who have undergone transplantation and their close contacts. 469 Vaccinations for healthcare personnel.…”

Trends in Influenza Vaccine Coverage in Pregnant Women, 2008 to 2012

“…21,22 There is also evidence that infants of vaccinated mothers have increased passive immunity, as well as significantly fewer influenza infections and hospitalizations than infants of unvaccinated mothers. 6,20,[23][24][25] Despite the recommendations of professional medical societies and good evidence for its benefits, influenza vaccination rates in pregnant women have historically been low. 6 Before 2009, vaccination coverage in pregnant women ranged from less than 10% to 33%.…”