Profile of respiratory syncytial virus prefusogenic fusion protein nanoparticle vaccine

INTRODUCTION

Respiratory Syncytial Virus (RSV) is a leading cause of acute lower respiratory infections worldwide. The RSV fusion (F) glycoprotein is a major focus of vaccine development. Despite over 60 years of research, there is no licensed vaccine for RSV.

AREAS COVERED

The primary focus of this review is a novel RSV-F recombinant nanoparticle vaccine from Novavax utilizing the F protein, a conserved and immunodominant surface glycoprotein. This RSV F recombinant nanoparticle vaccine adsorbed to 0.4 mg of aluminum phosphate was ultimately administered by a single intramuscular injection during the third trimester of pregnancy in an effort to induce passive immunity in newborns. Its mechanism, performance in clinical trials, and place in RSV vaccine history are discussed.

EXPERT OPINION

The vaccine was safe and well tolerated in pregnant women and the results suggest potential benefits with respect to other medically relevant end-point events involving RSV-associated respiratory and all-cause disease in infants. However, the RSV-F recombinant nanoparticle vaccine did not meet the pre-specified primary success criteria for efficacy against RSV-associated, medically significant lower respiratory tract infection in infants up to 90 days of life. The potential benefits to infants from maternal immunization and excellent safety profile warrant further confirmatory studies.

Impact of Timing of Influenza Vaccination in Pregnancy on Transplacental Antibody Transfer, Influenza Incidence, and Birth Outcomes: A Randomized Trial in Rural Nepal

Background

Maternal influenza vaccination protects mothers and their infants in low resource settings, but little is known about whether the protection varies by gestational age at vaccination.

Methods

Women of childbearing age in rural southern Nepal were surveilled for pregnancy, consented and randomized to receive maternal influenza vaccination or placebo, with randomization stratified on gestational age (17-25 or 26-34 weeks). Enrollment occurred in 2 annual cohorts, and vaccinations occurred from April 2011 through September 2013.

Results

In sum, 3693 women consented and enrolled, resulting in 3646 live births. Although cord blood antibody titers and the rise in maternal titers were generally greater when women were vaccinated later in pregnancy, this was not statistically significant. The incidence risk ratio (IRR) for maternal influenza in pregnancy through 6 months postpartum was 0.62 (95% confidence interval [CI]: 0.35, 1.10) for those vaccinated 17-25 weeks gestation and 0.89 (95% CI: 0.39, 2.00) for those 26-34 weeks. Infant influenza IRRs were 0.73 (95% CI: 0.51, 1.05) for those whose mothers were vaccinated earlier in gestation, and 0.63 (95% CI: 0.37, 1.08) for those later. Relative risks (RR) for low birthweight were 0.83 (95% CI: 0.71, 0.98) and 0.90 (95% CI: 0.72, 1.12) for 17-25 and 26-34 weeks gestation at vaccination, respectively. IRRs did not differ for small-for-gestational age or preterm. No RRs were statistically different by timing of vaccine receipt.

Conclusions

Vaccine efficacy did not vary by gestational age at vaccination, making maternal influenza immunization programs easier to implement where women present for care late in pregnancy.

Clinical Trials Registration

NCT01034254.