The Impact of Maternal Influenza Vaccination on Reducing Morbidity in Postpartum Mothers and Their Infants: A Prospective Cohort Study

• Hanif Shaikh,*  
• Pranesha Koli,  
• Anil Pardeshi,  
• Parveen Shaikh,  
• Suneth Agampodi,  
• Sushant Sahastrabuddhe,  
• Anand Kawade,  
• Chandrashekhar Upasani

Abstract

Introduction: Influenza during pregnancy poses risks to both mothers and infants, leading to increased morbidity. Maternal vaccination is recommended to reduce these risks, but its impact on postpartum health has not been fully explored. This study evaluates the effect of maternal influenza vaccination on the incidence of influenza-like illnesses in mothers and their infants during the first three months postpartum. Aim and Objective: To Assess the impact of maternal influenza vaccination in reducing the incidence of influenza-related morbidity among mothers and their infants during initial three months. Methods: This prospective cohort study was conducted on postpartum mothers at Yashwantrao Chavan Memorial Hospital in Pimpri, Pune between October 2019 and May 2020. These women, either vaccinated with the seasonal influenza vaccine during pregnancy or not, were observed for three months after birth to assess the occurrence of influenza-like illnesses in both the mothers and their infants collected through during clinic visit or weekly telephonic interview. Results: Out of 542 women initially participated, 160 vaccinated participants and 172 unvaccinated participants completed three months follow up. No significant differences in the influenza related morbidity observed between the two groups. In infants, after employing Poisson regression models, adjusting for prematurity, birth weight, and maternal ILI, the adjusted incidence rate ratios (IRRs) revealed that maternal influenza vaccination significantly reduced hospitalization incidence (IRR: -3.38, 95% CI: -1.97, p=0.001) and the clinician encounters (IRR: -2.18, 95% CI: -0.92, p=0.03). However, effects on ILI incidence (IRR: -1.48, 95% CI: -0.84 to 0.12) were not statistically significant. Maternal ILI emerged as a crucial predictor for infant ILI incidence (IRR: 4.16, 95% CI: 0.49-1.38, p<0.001), clinician encounters (IRR: 3.44, 95% CI: 0.31 to 1.15, p<0.001), and hospitalization (IRR: 4.22, 95% CI: 0.53-1.45, p<0.001). Conclusion: Maternal influenza vaccination significantly lowers the risk of hospitalizations and clinician visits due to ILI in infants. Also, maternal ILI noted as a significant predictor of the Infant influenza related morbidity, underscoring the indirect benefits of vaccinating pregnant women beyond the direct protection offered to the infants.

Keywords

Influenza Vaccine, Postnatal Morbidity, Maternal Immunization, Influenza Like Illness.