Respiratory syncytial virus (RSV) is the leading cause of viral lower respiratory
tract illness in infants and children and is an important cause of lower respiratory
tract illness in other populations. Despite decades of research there are currently
no licensed vaccines for prevention of RSV disease.
A review of the obstacles to RSV vaccine development; current live, attenuated and
subunit RSV vaccines in clinical development; and the potential for developing additional
vaccine candidates based on recombinant technology.
A number of biologically derived live attenuated RSV vaccines were evaluated in Phase
I clinical trials in adults and children, and one vaccine (cpts 248/404) was evaluated in
infants as young as 1 month of age. These vaccines displayed a spectrum of attenuation,
with cpts 248/955 being the least attenuated and cpts 248/404 being the most attenuated
candidate vaccine. None of these was sufficiently attenuated for young infants. The ability
to generate recombinant RSV vaccines has led to the development of large numbers of
candidate vaccines containing combinations of known attenuating point mutations and
deletions of nonessential genes. Clinical evaluation of many of these candidates is in
progress. Three types of RSV subunit vaccines have recently been evaluated in clinical
trials: purified F glycoprotein vaccines (PFP-1, PFP-2 and PFP-3), BBG2Na and copurified
F, G and M proteins. Additional studies of the F/G/M protein vaccine are being conducted.