SOUTH SAN FRANCISCO, Calif.,
Oct. 7, 2021 /PRNewswire/ -- A
Duke University-led study published in
bioRxiv showed that Vaxart, Inc.'s (NASDAQ: VXRT) investigational
oral tablet vaccine reduced the airborne transmission of SARS-CoV-2
virus in an animal model.
These results are consistent with those from Vaxart's Phase II
human flu challenge study, which showed that Vaxart's oral tablet
vaccine was better at reducing shedding than the injectable flu
vaccine comparator.
A limitation of the currently approved injected COVID-19
vaccines is that airborne transmission occurs in people who have
received them. The preclinical study also demonstrated that
Vaxart's oral vaccine platform induces robust systemic and mucosal
responses.
Researchers vaccinated hamsters orally or intranasally with
Vaxart's S-only vaccine candidate and then exposed them to
significant levels of the COVID-19 virus to promote vaccine
breakthrough. Vaccinated hamsters cleared infectious virus in the
nose and lungs quickly. Before clearing the infection, the
vaccinated hamsters were exposed to unvaccinated hamsters via
aerosol. The mucosally vaccinated hamsters infected fewer hamsters
and created less severe clinical symptoms than did unvaccinated
hamsters.
"These findings show that our vaccine candidate can reduce
transmission of SARS-CoV-2, even when there is infection
breakthrough in vaccinated subjects," said Dr. Sean Tucker, the study's lead author and Chief
Scientific Officer at Vaxart.
"Existing injected vaccines don't always protect against viral
shedding and transmission to other people. A vaccine that reduces
shedding and reduces the probability of infection could make a big
difference in protecting lives and public health, particularly
given the large number of unvaccinated individuals. This study used
the same vaccine candidate Vaxart is using in its development of an
oral tablet vaccine," added Dr. Tucker.
Earlier this week, Vaxart initiated recruiting for a global
Phase II clinical trial of its oral tablet COVID-19 vaccine
candidate, which targets the SARS-CoV-2 viral spike (S)
protein.
"Vaxart previously published data from a human influenza
challenge study that demonstrated our oral flu vaccine candidate
inhibited shedding of viral RNA better than injectable vaccines.
The data reported provides further evidence that our oral vaccine
could offer both an easier, more attractive mode of administration
and potentially superior protection against respiratory viruses,"
said Andrei Floroiu, Vaxart's Chief
Executive Officer.
The mucosal surface of the upper respiratory tract is the
initial site of SARS-CoV-2 replication and the primary site of
infection. Vaccines that induce robust mucosal immune responses may
have the greatest impact on reduction of SARS-CoV-2 transmission.
Approved COVID-19 vaccines, all of which are administered via
intramuscular injection, stimulate systemic immune responses but
have minimal effects on mucosal immunity.
About the Study
The study used a hamster infection and aerosol transmission
system to study the potential impact of oral vaccination on
transmission of SARS-CoV-2 to uninfected individuals.
Animals received oral, intranasal or intramuscular vaccines
targeting S protein, and a control group received a mock
vaccination (four animals per group). These index hamsters were
then infected intranasally with a high titer of SARS-CoV-2 to
replicate a post-vaccination breakthrough infection.
One day after viral challenge, index hamsters were placed
upstream of unvaccinated hamsters in a chamber that allowed aerosol
movement but not direct contact with other animals or bedding or
feeding receptacles used by other animals. Index animals were
evaluated for antibodies for systemic (IgG) and mucosal (IgA)
immunity; all animals were evaluated for viral titers and body
weight and lung weight (indicators of SARS-CoV-2 infection).
Key Findings
Key findings from the study include:
- Oral and intranasal vaccination against S protein induced
robust systemic and mucosal antibody responses.
-
- Post-vaccination, the oral and intranasal groups had higher
serum IgG and IgA, as well as higher bronchoalveolar lavage (BAL)
IgA compared to control animals.
- Oral and intranasal vaccination accelerated clearance of
SARS-CoV-2 RNA and protected animals against disease.
-
- Following intranasal delivery of SARS-CoV-2 and detection of
substantial amounts of viral RNA in nasal swabs, vaccinated
hamsters had decreased viral RNA and infectious virus in the nose
and lungs and experienced less lung pathology (determined by lung
weight) and lost less weight (a characteristic of SARS-CoV-2
disease in hamsters) compared to mock-vaccinated hamsters post
challenge.
- Oral and intranasal vaccination limited transmission of
SARS-CoV-2 to unvaccinated animals.
-
- Unvaccinated animals exposed to animals vaccinated orally or
intranasally shed lower nasal swab viral RNA than animals receiving
intramuscular or mock vaccinations.
- Taken together, these data demonstrate that oral immunization
against SARS-CoV-2 S protein resulted in reduced disease and
decreased SARS-CoV-2 transmission in a hamster model.
About Vaxart
Vaxart is a clinical-stage biotechnology company developing
a range of oral recombinant vaccines based on its proprietary
delivery platform. Vaxart vaccines are designed to be
administered using tablets that can be stored and shipped without
refrigeration and eliminate the risk of needle-stick
injury. Vaxart believes that its proprietary tablet
vaccine delivery platform is suitable to deliver recombinant
vaccines, positioning the company to develop oral versions of
currently marketed vaccines and to design recombinant vaccines for
new indications. Vaxart's development programs currently
include tablet vaccines designed to protect against coronavirus,
norovirus, seasonal influenza, and respiratory syncytial virus
(RSV), as well as a therapeutic vaccine for human papillomavirus
(HPV), Vaxart's first immune-oncology
indication. Vaxart has filed broad domestic and
international patent applications covering its proprietary
technology and creations for oral vaccination using adenovirus and
TLR3 agonists.
Note Regarding Forward-Looking Statements
This press release contains forward-looking statements that involve
substantial risks and uncertainties. All statements, other than
statements of historical facts, included in this press release
regarding Vaxart's strategy, prospects, plans and
objectives, results from pre-clinical and clinical trials,
commercialization agreements and licenses, and beliefs and
expectations of management are forward-looking statements. These
forward-looking statements may be accompanied by such words as
"should," "believe," "could," "potential," "will," "expected,"
"plan," and other words and terms of similar meaning. Examples of
such statements include, but are not limited to, statements
relating to Vaxart's ability to develop and commercialize its
product candidates, including its vaccine booster
products; Vaxart's expectations regarding clinical
results and trial data; and Vaxart's expectations with
respect to the effectiveness of its product
candidates. Vaxart may not actually achieve the plans,
carry out the intentions, or meet the expectations or projections
disclosed in the forward-looking statements, and you should not
place undue reliance on these forward-looking statements. Actual
results or events could differ materially from the plans,
intentions, expectations, and projections disclosed in the
forward-looking statements. Various important factors could cause
actual results or events to differ materially from the
forward-looking statements that Vaxart makes, including
uncertainties inherent in research and development, including the
ability to meet anticipated clinical endpoints, commencement,
and/or completion dates for clinical trials, regulatory submission
dates, regulatory approval dates, and/or launch dates, as well as
the possibility of unfavorable new clinical data and further
analyses of existing clinical data; the risk that clinical trial
data are subject to differing interpretations and assessments by
regulatory authorities; whether regulatory authorities will be
satisfied with the design of and results from the clinical studies;
decisions by regulatory authorities impacting labeling,
manufacturing processes, and safety that could affect the
availability or commercial potential of any product candidate,
including the possibility that Vaxart's product
candidates may not be approved by the FDA or non-U.S. regulatory
authorities; that, even if approved by the FDA or non-U.S.
regulatory authorities, Vaxart's product candidates may
not achieve broad market acceptance; that
a Vaxart collaborator may not attain development and
commercial milestones; that Vaxart or its
partners may experience manufacturing issues and delays due to
events within, or outside of, Vaxart's or its partners'
control; difficulties in production, particularly in scaling up
initial production, including difficulties with production costs
and yields, quality control, including stability of the product
candidate and quality assurance testing, shortages of qualified
personnel or key raw materials, and compliance with strictly
enforced federal, state, and foreign regulations;
that Vaxart may not be able to obtain, maintain, and
enforce necessary patent and other intellectual property
protection; that Vaxart's capital resources may be
inadequate; Vaxart's ability to resolve pending legal
matters; Vaxart's ability to obtain sufficient capital to
fund its operations on terms acceptable to Vaxart, if at all;
the impact of government healthcare proposals and policies;
competitive factors; and other risks described in the "Risk
Factors" sections of Vaxart's Quarterly and Annual
Reports filed with the SEC. Vaxart does not assume any
obligation to update any forward-looking statements, except as
required by law.
Contacts
Vaxart Media Relations
Mark Herr
Vaxart, Inc.
mherr@vaxart.com
(203) 517-8957
Investor Relations
IR@Vaxart.com
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SOURCE Vaxart, Inc.