History of Dengue Vaccine
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Dengue Vaccines Market |
To reduce the danger of severe dengue infection in patients
infected with one of the four virus serotypes not included in immunisation,
experts agree that a dengue vaccine must be effective against all four virus
serotypes. The only licenced dengue vaccine is Sanofi Pasteur's Dengvaxia,
which is registered in several endemic countries, Europe, and the United
States. This vaccine is made up of four live-attenuated chimeric viruses with
the backbone of yellow fever virus, a flavivirus with a genomic organisation
similar to dengue, in which the prM and E genes from the four DENV viruses have
been replaced.
The global dengue
vaccine market is estimated to account for US$ 1,262.0 Mn in terms of value by the end of 2027.
The vaccine was not totally protective against all
serotypes, especially DENV2, according to results from phase 2 clinical trials
with children in Asia. Because those youngsters had large amounts of NAb
against all dengue serotypes, these findings suggested that induction of
neutralising antibodies might not be enough to offer protection, and they also
suggested the necessity of T-cell responses. Other DENV antigens not found in
Dengvaxia, such as non-structural proteins, may be critical for generating
substantial protection, according to the report. DENV seronegative patients,
primarily children, became more susceptible to DHF when infected following
vaccination, according to phase 4 trials conducted in the Philippines and
Brazil. As a result of these findings, the WHO now exclusively recommends
Dengvaxia vaccination to dengue seropositive people. Dengvaxia, on the other
hand, is thought to be effective for at least 5 years in seropositive people.
Several additional vaccines have been studied in preclinical
investigations using various animal models, with some of them progressing to
clinical trials. Two dengue vaccines based on live-attenuated viruses are now
in phase 3 studies (TV003 and TAK-003). 30 nucleotides in the 3′ UTR of DENV1,
DENV3, and DENV4 were removed for attenuation, and prM/E genes from attenuated
DENV4 were replaced by the identical DENV2 genes, resulting in DENV2/4. The
vaccine was created by the National Institutes of Health in the United States
and is being evaluated in Brazil by the Instituto Butantan (Butantan-DV).
Seroconversion against the different serotypes ranged from 76 to 92 percent in phase
2 clinical trials with DENV-naive and DENV-exposed healthy individuals. CD8+
T-cell responses to non-structural dengue proteins were also associated with
IFN-production in vaccinees. When DENV-exposed people were compared to
DENV-naive people, neutralising antibody titers were 2–4 times greater.
Furthermore, the results demonstrated a link between antibody response and the
occurrence of adverse events, particularly rash.
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