CoronaVac® generates good immune memory after
second dose
Third dose of vaccine significantly increased
neutralizing antibody levels in adults and elderly population
Findings indicate a third dose of CoronaVac® is
well-tolerated in the elderly population
No serious vaccine-related adverse reactions
reported
SINOVAC Biotech Ltd. (NASDAQ: SVA) (“Sinovac” or the “Company”),
a leading provider of biopharmaceutical products in China,
announced today the publication of two papers, which are available
on Medrxiv. The publications detail findings from clinical studies
on the immunogenicity, safety, and immune response of CoronaVac® in
two- and three-dose schedules. The results indicate that a third
booster dose of CoronaVac® induces a strong immune response in
healthy adults with no serious adverse reactions related to the
vaccine. This research provides important scientific data and
supplement existing research to help policymakers develop
strategies for vaccine rollout and timing of booster doses.
The first paper, titled Immunogenicity and safety of a third
dose, and immune persistence of CoronaVac vaccine in healthy adults
aged 18-59 years: interim results from a double-blind, randomized,
placebo-controlled phase 2 clinical trial, includes published data
on the immunogenicity and safety profile of a two-dose schedule, as
well as interim results on immune persistence and the
immunogenicity and safety of a third dose of CoronaVac® in healthy
adults aged 18 to 59 years old.
The study is part of the placebo-controlled, double-blind phase
II clinical trial in healthy adults aged 18 to 59 years old,
conducted in China. Participants were randomly assigned (1:1:1:1)
to one of four schedules to receive a third dose of vaccine, 28 or
6 months after two two-dose regiments, 14 or 28 days apart. The
immunization schedule of the three-dose regimens for the four arms
were: (1) days 0, 14, 42; (2) days 0, 14, 54; (3) days 0, 28, 56;
and (4) days 0, 28, 268.
The results indicated that a two-dose schedule generates good
immune memory. A third dose given 6 to 8 months after the second
dose quickly induced a strong immune response, and the neutralizing
antibody titers at day 28 after the third dose increased by three
to five times higher than the levels recorded on day 28 after the
second injection. In addition, the findings revealed evidence that
show longer intervals between the second and third doses will
result in higher antibody levels.
Seropositive rates in all dose groups were above 90.0% on day 28
after both the second and third doses. The severity of solicited
local and systemic adverse reactions reported within 28 days after
the third dose were grade 1 to grade 2 in all vaccination cohorts.
No serious adverse reactions were considered to be related to
vaccination, and a lower rate of adverse reaction was observed
after the third dose compared to the two-dose schedule.
The second paper, titled A booster dose is immunogenic and will
be needed for older adults who have completed two doses vaccination
with CoronaVac: a randomised, double-blind, placebo-controlled,
phase 1/2 clinical trial, includes published data on the
immunogenicity and safety profile of a third dose of CoronaVac® in
healthy adults aged 60 and above, as well as research on the immune
persistence of two priming doses.
The results showed that a third dose of the vaccine administered
8 months after the second dose can induce a significant increase of
neutralizing antibodies at day 7 post-injection. In addition, a
third dose was found to be well-tolerated in elderly patient
populations with no vaccine-related serious adverse events
reported.
The study is part of randomized, double-blind,
placebo-controlled, phase 1/2 clinical trial conducted in China in
healthy adults aged 60 and above, conducted in China. The study
recruited 303 participants that who were assigned to groups and
given a third dose of 3μg, 6μg or placebo eight months after the
second dose. An additional arm of 1.5μg per dose was added to the
study.
The results indicate that, in all 1.5μg, 3μg, and 6μg dose
vaccine groups, the level of neutralizing antibodies increased
significantly on day 7 after the third dose of vaccine. In the
group of participants who received the 3μg vaccine, which is
approved for emergency use, the geometric mean titer (GMT) of serum
neutralizing antibodies increased to 305 on day 7 after the third
dose of vaccine, which was approximately 7-fold as compared to the
levels at day 28 after the second dose. The GMT levels continued to
increase on days 14 and 28 after the third dose; however, there
were no significant differences in the levels recorded days 14, 28
and 7 after the administration of a third dose. Furthermore, no
significant differences in neutralizing antibody levels were
observed among different age groups (60 to 64 years old, 65 to 69
years old, 70 years old and above).
The safety data showed that, within 28 days after the subjects
received the third dose of vaccine, there was no significant
difference in incidence of adverse reactions between the different
arms vaccine and the placebo groups. Any reported adverse reactions
were grade 1 or 2, the most common reaction being injection-site
pain. No serious vaccine-related adverse reactions were
observed.
Reference
[1] Immunogenicity and safety of a third dose, and immune
persistence of CoronaVac vaccine in healthy adults aged 18-59
years: interim results from a double-blind, randomized,
placebo-controlled phase 2 clinical trial. doi:
https://doi.org/10.1101/2021.07.23.21261026
[2] A booster dose is immunogenic and will be needed for older
adults who have completed two doses vaccination with CoronaVac: a
randomised, double-blind, placebo-controlled, phase 1/2 clinical
trial. doi: https://doi.org/10.1101/2021.08.03.21261544
About SINOVAC
SINOVAC Biotech Ltd. is a China-based biopharmaceutical company
that focuses on the research, development, manufacturing and
commercialization of vaccines that protect against human infectious
diseases. SINOVAC's product portfolio includes vaccines against
COVID-19, enterovirus71 (EV71), hepatitis A and B, seasonal
influenza, 23-Valent pneumococcal polysaccharide (“PPV”), H5N1
pandemic influenza (avian flu), H1N1 influenza (swine flu),
varicella, mumps and Poliomyelitis. SINOVAC’s COVID-19 vaccine,
CoronaVac®, has been granted emergency use approval or conditional
marketing authorization by over 50 countries or regions worldwide.
Healive®, the hepatitis A vaccine manufactured by the Company, has
passed the assessment under WHO prequalification procedures in
2017. The EV71 vaccine, an innovative vaccine developed by SINOVAC
against hand foot and mouth disease caused by EV71, was
commercialized in China in 2016. In 2009, SINOVAC was the first
company worldwide to receive approval for its H1N1 influenza
vaccine, which it has supplied to the Chinese Government's
vaccination campaign and stockpiling program. The Company is also
the only supplier of the H5N1 pandemic influenza vaccine to the
government stockpiling program. In 2021, SINOVAC’s Sabin-strain
inactivated polio vaccine has approved for registration. The
Company is developing several new products including combined
vaccines. SINOVAC primarily sells its vaccines in China, while also
exploring growth opportunities in international markets. The
Company is seeking market authorization of its products in over 30
countries outside of China. For more information, please see the
Company’s website at www.sinovac.com.
Safe Harbor Statement
This press release may include certain statements that are not
descriptions of historical facts, but are forward-looking
statements. These statements are made under the “safe harbor”
provisions of the U.S. Private Securities Litigation Reform Act of
1995. These forward-looking statements can be identified by
terminology such as “will,” “expects,” “anticipates,” “future,”
“intends,” “plans,” “believes,” “estimates” and similar statements.
Forward-looking statements involve risks, uncertainties and other
factors that could cause actual results to differ materially from
those contained in any such statements. In particular, the outcome
of any litigation is uncertain, and the Company cannot predict the
potential results of the litigation it filed or filed against it by
others. Additionally, the triggering of a shareholder rights plan
is nearly unprecedented, and the Company cannot predict the impact
on the Company or its stock price as a result of the trigger of the
rights plan.
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version on businesswire.com: https://www.businesswire.com/news/home/20210810005405/en/
Sinovac Biotech Ltd. Helen Yang Tel: +86-10-8279-9871 or
+86-10-5693-1897 Fax: +86-10-6296-6910 Email: ir@sinovac.com
ICR Inc. Bill Zima U.S.: 1-646-308-1707 Email:
william.zima@icrinc.com
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