Respiratory Syncytial Virus Prefusion F Vaccination: Antibody Persistence and Revaccination.

BACKGROUND: Respiratory syncytial virus (RSV) causes substantial respiratory disease. Bivalent RSV prefusion F (RSVpreF) vaccine is licensed in ≥60-year-olds. RSVpreF was well-tolerated and immunogenic in a phase 1/2 study. We evaluated antibody persistence after initial vaccination and safety and immunogenicity after revaccination from this study. METHODS: Healthy adults were randomized to receive both initial vaccination and revaccination 12 months later with either placebo or RSVpreF 240 µg (±Al(OH)3). RSV-A and RSV-B geometric mean neutralizing titers (GMTs) were measured through 12 months after both vaccinations. Tolerability/safety was assessed. RESULTS: There were 263 participants revaccinated (18-49-years-old, n=134; 65-85-years-old, n=129). Among 18-49-year-olds and 65-85-year-olds, respectively, geometric mean fold rises (GMFRs) for both RSV subgroups (RSV-A; RSV-B) 1 month after initial RSVpreF vaccination were 13.3-20.4 and 8.9-15.5 compared with levels before initial vaccination; corresponding GMFRs 12 months after initial vaccination were 4.1-5.0 and 2.6-4.1. GMFRs 1 month after revaccination compared with levels before revaccination were 1.4-2.3 and 1.4-2.2 for 18-49-year-olds and 65-85-year-olds, respectively. Peak GMTs after revaccination were lower than those after initial vaccination. GMTs 12 months after initial vaccination and revaccination were similar, with GMFRs ranging from 0.7-1.6. No safety signals occurred. CONCLUSIONS: RSVpreF revaccination was immunogenic and well-tolerated among adults. NCT03529773.

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.).

Vaccine Efficacy in Adults in a Respiratory Syncytial Virus Challenge Study.

BACKGROUND: Although human respiratory syncytial virus (RSV) is an important cause of illness and death in older adults, no RSV vaccine has been licensed. METHODS: In a phase 2a study, we randomly assigned healthy adults (18 to 50 years of age), in a 1:1 ratio, to receive a single intramuscular injection of either bivalent prefusion F (RSVpreF) vaccine or placebo. Approximately 28 days after injection, participants were inoculated intranasally with the RSV A Memphis 37b challenge virus and observed for 12 days. The per-protocol prespecified primary end points were the following: reverse-transcriptase-quantitative polymerase-chain-reaction (RT-qPCR)-confirmed detectable RSV infection on at least 2 consecutive days with at least one clinical symptom of any grade from two categories or at least one grade 2 symptom from any category, the total symptom score from day 1 to discharge, and the area under the curve (AUC) for the RSV viral load in nasal-wash samples measured by means of RT-qPCR from day 2 after challenge to discharge. In addition, we assessed immunogenicity and safety. RESULTS: After participants were inoculated with the challenge virus, vaccine efficacy of 86.7% (95% CI, 53.8 to 96.5) was observed for symptomatic RSV infection confirmed by any detectable viral RNA on at least 2 consecutive days. The median AUC for the RSV viral load (hours × log10 copies per milliliter) as measured by RT-qPCR assay was 0.0 (interquartile range, 0.0 to 19.0) in the vaccine group and 96.7 (interquartile range, 0.0 to 675.3) in the placebo group. The geometric mean factor increase from baseline in RSV A-neutralizing titers 28 days after injection was 20.5 (95% CI, 16.6 to 25.3) in the vaccine group and 1.1 (95% CI, 0.9 to 1.3) in the placebo group. More local injection-site pain was noted in the vaccine group than in the placebo group. No serious adverse events were observed in either group. CONCLUSIONS: RSVpreF vaccine was effective against symptomatic RSV infection and viral shedding. No evident safety concerns were identified. These findings provide support for further evaluation of RSVpreF vaccine in a phase 3 efficacy study. (Funded by Pfizer; EudraCT number, 2020-003887-21; ClinicalTrials.gov number, NCT04785612.).

Safety and Immunogenicity of a Respiratory Syncytial Virus Prefusion F Vaccine When Coadministered With a Tetanus, Diphtheria, and Acellular Pertussis Vaccine.

BACKGROUND: Prevention of respiratory syncytial virus (RSV) disease in infants is an unmet vaccine need, and maternal immunization is a potential strategy to address this need. This study evaluated concomitant administration of RSV stabilized prefusion F subunit vaccine (RSVpreF) and tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine adsorbed (Tdap) in healthy, nonpregnant women 18‒49 years of age. METHODS: In this phase 2b, multicenter, placebo-controlled, observer-blind, noninferiority study, participants were randomized to receive RSVpreF in a range of doses and formulations with Tdap or alone, or Tdap alone. Safety and immunogenicity were assessed. RESULTS: Local reactions and systemic events were generally similar across vaccine groups. Noninferiority of anti-RSV-A and anti-RSV-B immune responses induced by RSVpreF with Tdap was demonstrated compared to RSVpreF alone. Noninferiority of anti-diphtheria toxoid and anti-tetanus toxoid immune responses after administration of RSVpreF with Tdap was demonstrated compared to Tdap alone; noninferiority was not met for anti-pertussis component responses. CONCLUSIONS: RSVpreF was safe and well tolerated when administered with Tdap or alone in nonpregnant women 18‒49 years of age. Immune responses induced by Tdap administered with RSVpreF were noninferior for the tetanus and diphtheria components of Tdap, but not for pertussis. CLINICAL TRIALS REGISTRATION: NCT04071158.

Phase 1/2 Randomized Study of the Immunogenicity, Safety, and Tolerability of a Respiratory Syncytial Virus Prefusion F Vaccine in Adults With Concomitant Inactivated Influenza Vaccine.

BACKGROUND: Respiratory syncytial virus (RSV) causes substantial morbidity and mortality in older adults and adults with comorbidities. An effective vaccine is needed. An investigational bivalent prefusion F vaccine (RSVpreF) was assessed in healthy adults. METHODS: This phase 1/2 study randomized adults 18-85 years old to receive placebo or 60, 120, or 240 µg RSVpreF (with or without aluminum hydroxide) alone or concomitantly with seasonal inactivated influenza vaccine (SIIV). Safety and immunogenicity were assessed. RESULTS: In older adults, reactogenicity events were predominantly mild or moderate among RSVpreF recipients; adverse events through 1 month postvaccination were similar across formulations. Coadministration with SIIV did not appear to affect safety among younger or older adults. All RSVpreF formulations with or without concomitant SIIV elicited robust RSV serum-neutralizing responses in adults aged 50-85 years 1 month postvaccination. Neutralizing titers 1 and 12 months postvaccination were 6.9-14.9 and 2.9-4.5 times, respectively, those before vaccination. SIIV immune responses trended lower when coadministered with RSVpreF. CONCLUSIONS: RSVpreF formulations administered alone or with SIIV were well tolerated and highly immunogenic in older adults, supporting the potential for RSVpreF to protect older adults from RSV disease. CLINICAL TRIALS REGISTRATION: NCT03529773.

A Randomized Phase 1/2 Study of a Respiratory Syncytial Virus Prefusion F Vaccine.

BACKGROUND: Protection against human respiratory syncytial virus (RSV) remains an unmet need potentially addressable by maternal immunization. This phase 1/2 study evaluated a bivalent prefusion F vaccine (RSVpreF) with antigens from RSV subgroups A and B. METHODS: Adults 18-49 years old (N = 618) were randomized to receive placebo or 60, 120, or 240 µg RSVpreF with or without Al(OH)3. Safety and immunogenicity were evaluated. RESULTS: RSVpreF recipients more frequently reported local reactions and systemic events than placebo recipients; these were mostly mild or moderate. No vaccine-related serious adverse events occurred through 12 months postvaccination. All RSVpreF formulations induced 1-month postvaccination virus-neutralizing titers higher than those associated with protection of high-risk infants by palivizumab, the only prophylactic currently available for RSV. Geometric mean fold rises (GMFRs) across RSVpreF doses/formulations were 10.6-16.9 for RSV A and 10.3-19.8 for RSV B at 1 month postvaccination, greater than those historically elicited by postfusion F vaccines. GMFRs were 3.9-5.2 and 3.7-5.1, respectively, at 12 months postvaccination. CONCLUSIONS: RSVpreF formulations were safe, well tolerated, and induced robust neutralizing responses in adults. These findings support development of RSVpreF, which is being evaluated in a pivotal phase 3 study for maternal immunization. CLINICAL TRIALS REGISTRATION: NCT03529773.

Loss of melanin from human RPE with aging: possible role of melanin photooxidation.

The pigment melanin, which is believed to play a photoprotective role, was quantified here in human RPE cells from donors of different age. Electron spin resonance (ESR) spectroscopy was shown to provide a quantitative measure of melanin and was used as a non-destructive measure of melanin content. Results indicated an age-related melanin loss in RPE cells, with melanin content diminishing 2.5-fold between the first and the ninth decade of life. To determine whether photo-oxidation may contribute to age-related changes in RPE melanin, RPE in human eyecups, isolated human and bovine RPE cells, purified melanin granules, or synthetic dopa melanin were irradiated with various wavelengths and intensities of visible light. Samples were analysed for changes in melanin content by ESR spectroscopy, and by absorption and emission spectrophotometry. The concentration of hydrogen peroxide was measured in some samples, and some human eyecups were examined by transmission electron microscopy. Irradiation of RPE in eyecups with intense visible light was found to produce a time-dependent photobleaching of melanosomes that was accompanied by the formation of hydrogen peroxide. Photobleaching of isolated RPE melanosomes and synthetic dopa melanin resulted in enhanced melanin fluorescence, as previously shown for melanin from aged donors by others, and significantly reduced ESR signal intensity, resembling the changes in melanin with aging observed here. We conclude that the content of melanin in RPE cells undergoes an age-related change to which photo-oxidation may contribute. This observation raises the question of whether age-related changes in melanin reduce the photoprotective role of the pigment in aging RPE cells.