Publication in npj Vaccines Reports Cross-reactive and Long-Lasting Immune Responses for self-amplifying mRNA (samRNA) COVID-19 Vaccine Booster Administered Intradermally with PharmaJet Tropis®

• The GEMCOVAC^®-OM COVID-19 booster administered intradermally (ID) with PharmaJet’s Tropis elicited robust and durable memory B-cell and T-cell responses.
• The needle-free booster also induced antibody responses that are cross-reactive towards several SARS-CoV-2 strains.

PharmaJet^®, a company that strives to improve the performance and outcomes of injectables with its needle-free injection technology, today announced the npj Vaccines publication of Gennova Biopharmaceutical’s post hoc analysis of their Phase 3 clinical study, which evaluated the cellular immune breadth induced by their self-amplifying (samRNA) vaccine (GEMCOVAC-OM) administered as a booster with Tropis ID. The analysis, entitled Cellular immune breadth of an Omicron-specific, self-amplifying monovalent mRNA vaccine booster for COVID-19 showed that GEMCOVAC-OM, administered exclusively with Tropis, generated high levels of memory B-cell and T-cell responses, important elements of an effective immune reaction to new variants.

The ongoing emergence of new variants of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) poses a significant challenge to global public health, raising concerns about the effectiveness of current vaccines. To combat these new variants, booster vaccination strategies have been implemented to improve effectiveness, with an emphasis on the need to generate a diverse range of memory B-cells and T-cells.¹

The analysis showed that the GEMCOVAC-OM booster (administered with Tropis) induced a broad and long-lasting immune response. Specifically, the GEMCOVAC-OM cohort demonstrated significant elevated levels of cross-reactive antibody responses against XBB.1.5 and BA.2.86 variant strains, as well as memory B and T-cells.

“These findings are line with the expectation that intradermal delivery helps to elicit long lived and cross-reactive immune responses, important parameters in the context of rapidly evolving viruses,” noted Nathalie Landry, Chief Scientific Officer, PharmaJet. “Tropis complements the GEMCOVAC-OM booster vaccine by easily leveraging the rich network of dendritic cells, macrophages, and T cells in the dermal layer providing a more potent and broader immunogenic response than vaccinating into the muscle. The needle-free system ensures precise and consistent vaccine dosage, in addition to being safe and easy to use.”

For more information about PharmaJet visit https://pharmajet.com.

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¹ Kumar,D et al, Cellular immune breadth of an Omicron-specific, self-amplifying monovalent mRNA vaccine booster for COVID-19, npj Vaccines volume 10, Article number: 42 (2025)

About PharmaJet

The PharmaJet mission is to improve the performance and outcomes of injectables with our enabling technology that better activates the immune system. We are committed to helping our partners realize their research and commercialization goals while making an impact on public health. PharmaJet Precision Delivery Systems™ can improve vaccine effectiveness, allow for a preferred patient and caregiver experience, and offer a proven path to commercialization. They are also safe, fast, and easy-to-use. The Stratis^® System has U.S. FDA 510(k) marketing clearance, CE Mark, and WHO PQS certification to deliver medications and vaccines either intramuscularly or subcutaneously. The Tropis^® System has CE Mark and WHO PQS certification for intradermal injections. They are both commercially available for global immunization programs. For more information or if you are interested in partnering with PharmaJet visit https://pharmajet.com or contact PharmaJet here. Follow us on LinkedIn.

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