Phase IV Open-Label Single-Arm Study on Safety and Immunogenicity of PHH-1V111 Emulsion for Injection Against SARS-CoV-2 Variants in COVID-19 Patients

The primary objective is to assess the safety and tolerability of BIMERVAX® LP.8.1 and to quantify its immunogenicity against the Omicron LP.8.1 strain and other epidemiologically relevant SARS‑CoV‑2 variants at baseline and on Day 14, providing essential data on adverse‑event risk and potential protective immunity in the context of COVID‑19. The secondary objective is to evaluate immunogenicity by measuring total antibodies directed against the Receptor Binding Domain of the SARS‑CoV‑2 spike protein at baseline and Day 14, furnishing additional insight into the humoral response elicited by the vaccine.

The trial enrolled adults aged 65 years and older, inclusive of both female and male participants, who were classified as healthy volunteers or who had chronic conditions considered stable and well‑controlled. The sponsor did not provide the total number of participants. Subjects were selected based on clinical assessment of medical history and investigator judgment, required to provide written informed consent, and needed a negative rapid antigen test for COVID-19 at screening. Eligible individuals had completed a primary COVID‑19 vaccination series and at least one booster dose targeting an Omicron variant, with the most recent dose administered ≥ 6 months before baseline. No specific dietary or physical‑activity restrictions were stipulated, but participants had to be capable of adhering to all study visits and procedures.

The study is a Phase IV, open label, single arm investigation evaluating the safety, tolerability, and immunogenicity of BIMERVAX® LP.8.1 administered intramuscularly at a dose of 40 µg in adults ≥65 years with prior primary and booster vaccination against COVID‑19. After a screening visit confirming eligibility (including a negative rapid antigen test and stable chronic conditions), participants receive a single vaccination on Day 0. Follow‑up visits are scheduled on Day 7 to assess solicited local and systemic reactions, and on Day 14 for comprehensive immunogenicity sampling (neutralising antibody titres and binding antibody assays) and safety evaluation, including collection of unsolicited adverse events, serious adverse events, adverse events of special interest, and medically attended adverse events. The end‑of‑study visit coincides with Day 14, marking the final assessment of immunogenic endpoints. Participant involvement therefore spans approximately two weeks from the screening visit to the Day 14 visit. Early termination may occur if a participant experiences a grade 3 or higher adverse event deemed related to the investigational product, withdraws consent, is lost to follow‑up, or requires prohibited concomitant therapy that could confound safety or immunogenicity outcomes.

The investigational product is BIMERVAX LP.8.1, an emulsion for injection COVID‑19 vaccine containing the recombinant antigen phh‑1v111. It is supplied as a sterile emulsion for injection and is administered by a single intramuscular injection of 40 µg on Day 0.

No placebo or active comparator is used in this open‑label, single‑arm study. Participants receive the study vaccine in addition to any standard medical care required for routine health maintenance.

Compliance with the dosing schedule is verified by observation of the injection and by documented attendance at the follow‑up visit on Day 14, when safety and immunogenicity assessments are performed.

Efficacy will be evaluated by measuring immunogenicity against the Omicron LP.8.1 strain and other SARS‑CoV‑2 variants. The primary immunogenicity parameters include neutralising antibody titres determined as inhibitory concentration 50 (IC50) using a pseudovirion‑based neutralisation assay (PBNA). Titres will be reported as reciprocal concentrations for each participant and as geometric mean titres (GMT). Assessments are performed at Baseline (pre‑vaccination) and on Day 14 post‑vaccination, with geometric mean fold rise (GMFR) calculated for descriptive analysis between these time points.

Secondary immunogenicity endpoints comprise binding antibody titres measured by an electrochemiluminescence immunoassay (ECLIA). Individual titres and GMT will be obtained at Baseline and Day 14. Additionally, the proportion of participants achieving at least a two‑fold increase in total binding antibody titres from Baseline to Day 14 will be calculated.

All laboratory analyses will be conducted using validated assay protocols. Data will be collected according to the predefined schedule, processed centrally, and analyzed descriptively to summarize GMT, GMFR, and fold‑increase frequencies.