Bivalent Prefusion F Vaccine in Pregnancy to Prevent RSV Illness in Infants.

BACKGROUND: Whether vaccination during pregnancy could reduce the burden of respiratory syncytial virus (RSV)-associated lower respiratory tract illness in newborns and infants is uncertain. METHODS: In this phase 3, double-blind trial conducted in 18 countries, we randomly assigned, in a 1:1 ratio, pregnant women at 24 through 36 weeks' gestation to receive a single intramuscular injection of 120 µg of a bivalent RSV prefusion F protein-based (RSVpreF) vaccine or placebo. The two primary efficacy end points were medically attended severe RSV-associated lower respiratory tract illness and medically attended RSV-associated lower respiratory tract illness in infants within 90, 120, 150, and 180 days after birth. A lower boundary of the confidence interval for vaccine efficacy (99.5% confidence interval [CI] at 90 days; 97.58% CI at later intervals) greater than 20% was considered to meet the success criterion for vaccine efficacy with respect to the primary end points. RESULTS: At this prespecified interim analysis, the success criterion for vaccine efficacy was met with respect to one primary end point. Overall, 3682 maternal participants received vaccine and 3676 received placebo; 3570 and 3558 infants, respectively, were evaluated. Medically attended severe lower respiratory tract illness occurred within 90 days after birth in 6 infants of women in the vaccine group and 33 infants of women in the placebo group (vaccine efficacy, 81.8%; 99.5% CI, 40.6 to 96.3); 19 cases and 62 cases, respectively, occurred within 180 days after birth (vaccine efficacy, 69.4%; 97.58% CI, 44.3 to 84.1). Medically attended RSV-associated lower respiratory tract illness occurred within 90 days after birth in 24 infants of women in the vaccine group and 56 infants of women in the placebo group (vaccine efficacy, 57.1%; 99.5% CI, 14.7 to 79.8); these results did not meet the statistical success criterion. No safety signals were detected in maternal participants or in infants and toddlers up to 24 months of age. The incidences of adverse events reported within 1 month after injection or within 1 month after birth were similar in the vaccine group (13.8% of women and 37.1% of infants) and the placebo group (13.1% and 34.5%, respectively). CONCLUSIONS: RSVpreF vaccine administered during pregnancy was effective against medically attended severe RSV-associated lower respiratory tract illness in infants, and no safety concerns were identified. (Funded by Pfizer; MATISSE ClinicalTrials.gov number, NCT04424316.).

Efficacy and Safety of a Bivalent RSV Prefusion F Vaccine in Older Adults.

BACKGROUND: Respiratory syncytial virus (RSV) infection causes considerable illness in older adults. The efficacy and safety of an investigational bivalent RSV prefusion F protein-based (RSVpreF) vaccine in this population are unknown. METHODS: In this ongoing, phase 3 trial, we randomly assigned, in a 1:1 ratio, adults (≥60 years of age) to receive a single intramuscular injection of RSVpreF vaccine at a dose of 120 µg (RSV subgroups A and B, 60 µg each) or placebo. The two primary end points were vaccine efficacy against seasonal RSV-associated lower respiratory tract illness with at least two or at least three signs or symptoms. The secondary end point was vaccine efficacy against RSV-associated acute respiratory illness. RESULTS: At the interim analysis (data-cutoff date, July 14, 2022), 34,284 participants had received RSVpreF vaccine (17,215 participants) or placebo (17,069 participants). RSV-associated lower respiratory tract illness with at least two signs or symptoms occurred in 11 participants in the vaccine group (1.19 cases per 1000 person-years of observation) and 33 participants in the placebo group (3.58 cases per 1000 person-years of observation) (vaccine efficacy, 66.7%; 96.66% confidence interval [CI], 28.8 to 85.8); 2 cases (0.22 cases per 1000 person-years of observation) and 14 cases (1.52 cases per 1000 person-years of observation), respectively, occurred with at least three signs or symptoms (vaccine efficacy, 85.7%; 96.66% CI, 32.0 to 98.7). RSV-associated acute respiratory illness occurred in 22 participants in the vaccine group (2.38 cases per 1000 person-years of observation) and 58 participants in the placebo group (6.30 cases per 1000 person-years of observation) (vaccine efficacy, 62.1%; 95% CI, 37.1 to 77.9). The incidence of local reactions was higher with vaccine (12%) than with placebo (7%); the incidences of systemic events were similar (27% and 26%, respectively). Similar rates of adverse events through 1 month after injection were reported (vaccine, 9.0%; placebo, 8.5%), with 1.4% and 1.0%, respectively, considered by the investigators to be injection-related. Severe or life-threatening adverse events were reported in 0.5% of vaccine recipients and 0.4% of placebo recipients. Serious adverse events were reported in 2.3% of participants in each group through the data-cutoff date. CONCLUSIONS: RSVpreF vaccine prevented RSV-associated lower respiratory tract illness and RSV-associated acute respiratory illness in adults (≥60 years of age), without evident safety concerns. (Funded by Pfizer; RENOIR ClinicalTrials.gov number, NCT05035212; EudraCT number, 2021-003693-31.).

Respiratory Syncytial Virus Prefusion F Protein Vaccine in Older Adults.

BACKGROUND: Respiratory syncytial virus (RSV) is an important cause of acute respiratory infection, lower respiratory tract disease, clinical complications, and death in older adults. There is currently no licensed vaccine against RSV infection. METHODS: In an ongoing, international, placebo-controlled, phase 3 trial, we randomly assigned, in a 1:1 ratio, adults 60 years of age or older to receive a single dose of an AS01E-adjuvanted RSV prefusion F protein-based candidate vaccine (RSVPreF3 OA) or placebo before the RSV season. The primary objective was to show vaccine efficacy of one dose of the RSVPreF3 OA vaccine against RSV-related lower respiratory tract disease, confirmed by reverse-transcriptase polymerase chain reaction (RT-PCR), during one RSV season. The criterion for meeting the primary objective was a lower limit of the confidence interval around the efficacy estimate of more than 20%. Efficacy against severe RSV-related lower respiratory tract disease and RSV-related acute respiratory infection was assessed, and analyses according to RSV subtype (A and B) were performed. Safety was evaluated. RESULTS: A total of 24,966 participants received one dose of the RSVPreF3 OA vaccine (12,467 participants) or placebo (12,499). Over a median follow-up of 6.7 months, vaccine efficacy against RT-PCR-confirmed RSV-related lower respiratory tract disease was 82.6% (96.95% confidence interval [CI], 57.9 to 94.1), with 7 cases (1.0 per 1000 participant-years) in the vaccine group and 40 cases (5.8 per 1000 participant-years) in the placebo group. Vaccine efficacy was 94.1% (95% CI, 62.4 to 99.9) against severe RSV-related lower respiratory tract disease (assessed on the basis of clinical signs or by the investigator) and 71.7% (95% CI, 56.2 to 82.3) against RSV-related acute respiratory infection. Vaccine efficacy was similar against the RSV A and B subtypes (for RSV-related lower respiratory tract disease: 84.6% and 80.9%, respectively; for RSV-related acute respiratory infection: 71.9% and 70.6%, respectively). High vaccine efficacy was observed in various age groups and in participants with coexisting conditions. The RSVPreF3 OA vaccine was more reactogenic than placebo, but most adverse events for which reports were solicited were transient, with mild-to-moderate severity. The incidences of serious adverse events and potential immune-mediated diseases were similar in the two groups. CONCLUSIONS: A single dose of the RSVPreF3 OA vaccine had an acceptable safety profile and prevented RSV-related acute respiratory infection and lower respiratory tract disease and severe RSV-related lower respiratory tract disease in adults 60 years of age or older, regardless of RSV subtype and the presence of underlying coexisting conditions. (Funded by GlaxoSmithKline Biologicals; AReSVi-006 ClinicalTrials.gov number, NCT04886596.).

Efficacy and Safety of an Ad26.RSV.preF-RSV preF Protein Vaccine in Older Adults.

BACKGROUND: Respiratory syncytial virus (RSV) can cause serious lower respiratory tract disease in older adults, but no licensed RSV vaccine currently exists. An adenovirus serotype 26 RSV vector encoding a prefusion F (preF) protein (Ad26.RSV.preF) in combination with RSV preF protein was previously shown to elicit humoral and cellular immunogenicity. METHODS: We conducted a randomized, double-blind, placebo-controlled, phase 2b, proof-of-concept trial to evaluate the efficacy, immunogenicity, and safety of an Ad26.RSV.preF-RSV preF protein vaccine. Adults who were 65 years of age or older were randomly assigned in a 1:1 ratio to receive vaccine or placebo. The primary end point was the first occurrence of RSV-mediated lower respiratory tract disease that met one of three case definitions: three or more symptoms of lower respiratory tract infection (definition 1), two or more symptoms of lower respiratory tract infection (definition 2), and either two or more symptoms of lower respiratory tract infection or one or more symptoms of lower respiratory tract infection plus at least one systemic symptom (definition 3). RESULTS: Overall, 5782 participants were enrolled and received an injection. RSV-mediated lower respiratory tract disease meeting case definitions 1, 2, and 3 occurred in 6, 10, and 13 vaccine recipients and in 30, 40, and 43 placebo recipients, respectively. Vaccine efficacy was 80.0% (94.2% confidence interval [CI], 52.2 to 92.9), 75.0% (94.2% CI, 50.1 to 88.5), and 69.8% (94.2% CI, 43.7 to 84.7) for case definitions 1, 2, and 3, respectively. After vaccination, RSV A2 neutralizing antibody titers increased by a factor of 12.1 from baseline to day 15, a finding consistent with other immunogenicity measures. Percentages of participants with solicited local and systemic adverse events were higher in the vaccine group than in the placebo group (local, 37.9% vs. 8.4%; systemic, 41.4% vs. 16.4%); most adverse events were mild to moderate in severity. The frequency of serious adverse events was similar in the vaccine group and the placebo group (4.6% and 4.7%, respectively). CONCLUSIONS: In adults 65 years of age or older, Ad26.RSV.preF-RSV preF protein vaccine was immunogenic and prevented RSV-mediated lower respiratory tract disease. (Funded by Janssen Vaccines and Prevention; CYPRESS ClinicalTrials.gov number, NCT03982199.).

Prefusion F Protein-Based Respiratory Syncytial Virus Immunization in Pregnancy.

BACKGROUND: Respiratory syncytial virus (RSV), a major cause of illness and death in infants worldwide, could be prevented by vaccination during pregnancy. The efficacy, immunogenicity, and safety of a bivalent RSV prefusion F protein-based (RSVpreF) vaccine in pregnant women and their infants are uncertain. METHODS: In a phase 2b trial, we randomly assigned pregnant women, at 24 through 36 weeks' gestation, to receive either 120 or 240 µg of RSVpreF vaccine (with or without aluminum hydroxide) or placebo. The trial included safety end points and immunogenicity end points that, in this interim analysis, included 50% titers of RSV A, B, and combined A/B neutralizing antibodies in maternal serum at delivery and in umbilical-cord blood, as well as maternal-to-infant transplacental transfer ratios. RESULTS: This planned interim analysis included 406 women and 403 infants; 327 women (80.5%) received RSVpreF vaccine. Most postvaccination reactions were mild to moderate; the incidence of local reactions was higher among women who received RSVpreF vaccine containing aluminum hydroxide than among those who received RSVpreF vaccine without aluminum hydroxide. The incidences of adverse events in the women and infants were similar in the vaccine and placebo groups; the type and frequency of these events were consistent with the background incidences among pregnant women and infants. The geometric mean ratios of 50% neutralizing titers between the infants of vaccine recipients and those of placebo recipients ranged from 9.7 to 11.7 among those with RSV A neutralizing antibodies and from 13.6 to 16.8 among those with RSV B neutralizing antibodies. Transplacental neutralizing antibody transfer ratios ranged from 1.41 to 2.10 and were higher with nonaluminum formulations than with aluminum formulations. Across the range of assessed gestational ages, infants of women who were immunized had similar titers in umbilical-cord blood and similar transplacental transfer ratios. CONCLUSIONS: RSVpreF vaccine elicited neutralizing antibody responses with efficient transplacental transfer and without evident safety concerns. (Funded by Pfizer; ClinicalTrials.gov number, NCT04032093.).