HDT Bio’s technology uses self-replicating RNA and has the potential to deliver a COVID-19 vaccine targeting multiple variants, providing broad protection from disease and reduced transmission from breakthrough infections

Seattle, WA, (April 5, 2022) – HDT Bio Corp., a developer of immunotherapies for oncology and infectious diseases, announced today publication in eLife of results of preclinical research that demonstrate its RNA vaccine targeting specific SARS-CoV2 variants protects against infection in the upper respiratory tract, reducing potential for transmission. In addition, the animal studies showed that even when not matched against variants, HDT Bio’s RNA vaccine protects against lower respiratory tract infection and disease regardless of viral strain. 

“Our research demonstrates that targeting vaccines to a dominant strain, such as delta and omicron, could significantly slow the spread of the virus by reducing transmission from breakthrough infections,” said Steve Reed, Ph.D., HDT Bio CEO. “If you add to that the fact our LION™ system enables us to deliver a cassette of as many as five self-replicating RNA molecules, each targeting a different variant, we have the potential to make one vaccine that affords broad protection against SARS-CoV2.”

HDT Bio’s COVID-19 vaccine is significantly different from current mRNA vaccines. Using self-replicating RNA, which is designed to amplify itself inside the body, generates effective activation of the immune system at a much lower dose than current vaccines. The advantage of using a lower dose of RNA not only is improved overall safety, but also enables HDT Bio to deliver multiple RNA molecules in one vaccine targeting multiple variants of the virus. In order for vaccines using mRNA to deliver multiple RNA molecules, the dosage level of each molecule would have to be lowered to ensure safety, reducing the vaccine’s ability to generate effective immunity.

The preclinical research, titled “SARS-CoV2 variant-specific replicating RNA vaccines protect from disease and pathology and reduce viral shedding following challenge with heterologous SARS-CoV2 variants of concern,” was conducted in collaboration with the National Institute of Allergy and Infectious Diseases at the National Institutes of Health. It was published February 22, 2022, online by eLife a not-for-profit peer-reviewed open access scientific journal for the biomedical and life sciences.

The research involved dosing animals with a vaccine targeting a specific variant of SARS-CoV2: ancestral, alpha, or beta. The animals then were challenged with a virus variant matching that of the vaccine as well as virus variants not matching the vaccine.

The results showed that HDT Bio vaccines matched to a variant shut down the virus in the upper respiratory tract, which includes nasal passages, throat and windpipe. When challenged with a mismatched virus variant, HDT Bio’s vaccine still reduced infection of the upper respiratory tract and provided effective protection from infection of the lower respiratory tract and lungs, a site of infection that contributes to severe disease, hospitalization and death.   

HDT Bio is conducting clinical trials of its COVID-19 RNA vaccine in the U.S. and internationally with partners in Brazil, South Korea and China. HDT Bio is collaborating with SENAI CIMATEC in Brazil and Quratis in South Korea. The collaboration in China will be announced soon.


HDT Bio is a Seattle-based biopharmaceutical company dedicated to providing immunotherapies to people around the world, including those in historically underserved areas.  The company seeks to harness the body’s immune system to deliver therapies that narrowly target the specific areas of the body where they are needed.  HDT’s work focuses on oncological and infectious disease applications. HDT Bio’s founders are world leaders in the development of immune stimulants, including both therapeutics and therapy-enhancing adjuvants.  One of the company’s core technologies, RNA/LION™, combines formulation and adjuvant ingredients to stabilize and deliver RNA to the immune system to stimulate responses for therapy or vaccination. http://hdt.bio