Influenza and respiratory syncytial virus (RSV) vaccines for infants: Safety, immunogenicity, and efficacy

Respiratory viral infections in infants and young children frequently cause illness that can easily progress to hospitalization and death. There are currently no licensed vaccines to prevent respiratory viral disease in children younger than 6 months, reflecting safety concerns and the difficulty in inducing effective immune responses in infants. This review discusses vaccines that have been developed, or are currently being developed, against influenza and respiratory syncytial virus, with a focus on studies performed to demonstrate their safety and efficacy, and the impact of immunologic immaturity and maternal antibodies on the infant response to vaccines.

► Vaccines for the prevention of influenza and RSV disease in infants are needed.
► Maternal antibodies may protect against disease but may also inhibit vaccine take.
► Development of a balanced Th1/Th2-type response may be age dependent.
► Neutralizing IgG, sIgA and cytotoxic CD8+ T cells are all needed for protection.
► Clinical studies are needed to support safety, immunogenicity, and efficacy.