Influenza vaccination during pregnancy for prevention of influenza confirmed illness in the infants: A systematic review and meta-analysis

ABSTRACT

Infants younger than 6 months of age are at particular risk for serious illness from influenza infection. Currently available influenza vaccines are, however, not licensed for use in infants <6 months old. Influenza vaccination during pregnancy elicits robust antibody responses in the women that will protect the infants against influenza infection during the first few months of life. We aimed to determine the impact of influenza vaccination during pregnancy to prevent laboratory-confirmed influenza infection and influenza-associated hospitalisations in infants <6 months old.

An electronic search identified all studies assessing the proposed outcomes in infants after administration of influenza vaccine during pregnancy. Two meta-analyses were performed accordingly to studies restricting the evaluation to influenza-associated hospitalisations or not.

Four randomized control trials and 3 observational studies reported on the prevention of laboratory-confirmed influenza infection in infants <6 months old. Maternal influenza vaccination was associated with a 48% [95% confidence interval (CI): 33 to 59] reduced risk of infants having laboratory-confirmed influenza infection. Four observational studies reported on the prevention of hospitalizations associated with laboratory-confirmed influenza infection and the pool estimate was 72% (95%CI: 39% to 87%).

Receipt of influenza vaccine during pregnancy was associated with decreased risk of laboratory-confirmed influenza infection in the infants.

KEYWORDS:

• influenza
• pregnancy
• immunization
• laboratory-confirmed
• influenza infection
• infants

Disclosure of potential conflicts of interest

Authors declare no conflict of interest.

Acknowledgments

The authors would like to thank Stefano Tempia from the National Institute for Communicable Diseases, South Africa, Mark C Steinhoff from Cincinnati Children's Hospital Medical Center, USA and Saad Omer from Emory University, USA.

Funding

The authors had partial support from the South African Research Chairs Initiative of the Department of Science and Technology and National Research Foundation in Vaccine Preventable Diseases; and the Medical Research Council: Respiratory and Meningeal Pathogens Research Unit. The contents of this report are solely the responsibility of the authors and do not necessarily represent the official views of their institutions or organizations or of the sponsors.