Table 1.

Obstacles to RSV vaccine development

Animal models are not fully permissive for infection

Requirement for bivalent vaccine (two antigenic subgroups)

Young age of primary vaccine target population

Special safety concern when immunizing neonates

Immunologic immaturity of neonatal target population

Maternal antibodies inhibit immune responses in the target population

Disease occurs at the portal of entry (the respiratory mucosa)

Mucosal immunity to respiratory viruses is short-lived and incomplete

FI-RSV vaccine caused enhanced disease

Reproduced with permission from Crowe [86]