In March 2020, the WHO declared a pandemic of coronavirus disease 2019 (COVID-19), due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). ¹ With >8.8 million cases and >450,000 deaths reported globally, a vaccine is urgently needed. We report the available safety, tolerability, and immunogenicity data from an ongoing placebo-controlled, observer-blinded dose escalation study among healthy adults, 18-55 years of age, randomized to receive 2 doses, separated by 21 days, of 10 μg, 30 μg, or 100 μg of BNT162b1, a lipid nanoparticle-formulated, nucleoside-modified, mRNA vaccine that encodes trimerized SARS-CoV-2 spike glycoprotein RBD. Local reactions and systemic events were dose-dependent, generally mild to moderate, and transient. RBD-binding IgG concentrations and SARS-CoV-2 neutralizing titers in sera increased with dose level and after a second dose. Geometric mean neutralizing titers reached 1.8-to 2.8-fold that of a panel of COVID-19 convalescent human sera. These results support further evaluation of this mRNA vaccine candidate.

A randomized, double-blind, phase 3 trial evaluated the immunogenicity, safety, and tolerability of a 13-valent pneumococcal conjugate vaccine (PCV13) coadministered with trivalent inactivated influenza vaccine (TIV) in pneumococcal vaccine-naive adults. Participants ages 50 to 59 years (n= 1,116) received TIV with PCV13 (group 1) or placebo (group 2) (1:1 randomization); 1 month later, group 1 received placebo and group 2 received PCV13. A hemagglutination inhibition (HAI) assay for TIV and a standardized enzyme-linked immunosorbent assay for pneumococcal serotype-specific immunoglobulin G (IgG) were performed and opsonophagocytic activity (OPA) titers (assessedpost hoc) were measured at baseline and 1 and 2 months postvaccination. The rises in HAI assay geometric mean titer (GMT) and percentage of participants in groups 1 and 2 with ≥4-fold increases in HAI responses (A/H1N1, 84.0% and 81.2%, respectively; A/H3N2, 71.1% and 69.5%, respectively; and B, 60.6% and 60.3%, respectively) were similar. In group 1, all serotypes met the predefined IgG geometric mean concentration (GMC) ratio noninferiority criterion relative to group 2, but GMCs were lower in group 1 than group 2. When comparing group 1 with group 2, 5 serotypes did not meet the OPA GMT ratio noninferiority criterion, and OPA GMTs were significantly lower for 10 serotypes. PCV13 injection site reactions were similar and mostly mild in both groups. Systemic events were more frequent in group 1 (86.2%) than group 2 (76.7%;P< 0.001); no vaccine-related serious adverse events occurred. Coadministration of PCV13 and TIV was well tolerated but associated with lower PCV13 antibody responses and is of unknown clinical significance. Given the positive immunologic attributes of PCV13, concomitant administration with TIV should be dictated by clinical circumstances.

A prophylactic Staphylococcus aureus four-antigen vaccine (SA4Ag) is under development for prevention of invasive S. aureus disease. A preliminary S. aureus three-antigen vaccine (SA3Ag) was reformulated to include a novel manganese transporter protein (MntC or rP305A). This study describes the first-in-human dose-finding, safety, and immunogenicity results for SA4Ag. In this double-blind, sponsor-unblind, placebo-controlled, phase 1/2 study, 454 healthy adults aged 18-64years were randomised to receive a single dose of one of three formulations of SA4Ag with escalating dose levels of rP305A or placebo. Functional immune responses were measured using opsonophagocytic activity (OPA) killing and fibrinogen-binding inhibition (FBI) assays; antigen-specific immunogenicity was assessed using a four-plex competitive Luminex® immunoassay (cLIA). A high proportion of SA4Ag recipients met the pre-defined antibody thresholds for each antigen at Day 29. A substantial and dose-level dependent immune response was observed for rP305A, with up to 18-fold rises in cLIA titres at Day 29. Robust functional responses were demonstrated, with >80-fold and >20-fold rises in OPA assay titres at Day 29 using S. aureus strains expressing capsular polysaccharide serotypes 5 and 8, respectively. Durable antibody responses were observed through month 12, gradually waning from peak levels achieved by days 11-15. SA4Ag was well tolerated, and no vaccine-related serious adverse events were reported. Single-dose vaccination of SA4Ag in healthy adults aged 18-64years safely induced rapid and robust functional immune responses that were durable through month 12, supporting further development of this vaccine. NCT01364571.