THE end to malaria infection is in sight as
the first malaria vaccine candidate to reach
phase-3 of clinical testing, and found to
partially protect children against the
disease up to four years after vaccination,
is set to be available by October this year,
scientists have reported.
Giving the hint about this development
yesterday, Brian Greenwood, corresponding
author and Professor of Clinical Tropical
Medicine at London School of Hygiene &
Tropical Medicine in the UK, explained that
results of the tests suggested that the
vaccine candidate known as RTS, S/AS01
could prevent a substantial number of
cases of clinical malaria, especially in
areas of high transmission.
Greenwood noted that the European
Medicines Agency, EMA, will “assess the
quality, safety, and efficacy of the vaccine
based on these final data. There is
currently no licensed vaccine against
malaria anywhere in the world.”
If the EMA gives a favourable opinion, the
World Health Organisation could
recommend the use of RTS,S/AS01 as early
as October this year. If licensed, RTS,S/
AS01 would be the first licensed human
vaccine against a parasitic disease,”
Greenwood added.
The findings, published in the journal, The
Lancet, revealed that vaccine efficacy
against clinical and severe malaria was
better in children than in young infants,
but waned over time in both groups.
However, protection was prolonged by a
booster dose, increasing the average
number of cases prevented in both
children and young infants.
Further, Greenwood argued that despite the
falling efficacy over time, there is still a
clear benefit from RTS,S/AS01.
“An average of 1,363 cases of clinical
malaria were prevented over four years of
follow-up for every 1,000 children
vaccinated, and 1,774 cases in those who
also received a booster shot. Over three
years of follow-up, an average 558 cases
were averted for every 1,000 infants
vaccinated, and 983 cases in those also
given a booster dose.
“Given that there were an estimated 198
million malaria cases in 2013, this level of
efficacy potentially translates into millions
of cases of malaria in children being
prevented,” he said.
The RTS,S/AS01 vaccine was developed
for use in sub-Saharan Africa where
malaria still kills around 1,300 children
every day. The phase-3 randomised trial
enrolled 15,459 young infants (aged six to
12 weeks at first vaccination) and children
(five to 17 months at first vaccination)
from 11 sites across seven sub-Saharan
African countries (Burkina Faso, Gabon,
Ghana, Kenya, Malawi, Mozambique and
United Republic of Tanzania) with varying
levels of malaria transmission.
In 2014, initial phase-3 results at 18
months showed vaccine efficacy of about
46 per cent against clinical malaria in
children and around 27 per cent among
young infants.
In this study, members of the RTS, S/AS01
Clinical Trials Partnership followed up the
infants and children for a further 20 to 30
months, respectively, and assessed the
impact of a fourth booster dose.
Participants were each vaccinated three
times with RTS,S/AS01 with or without a
booster dose 18 months later, or given four
doses of a comparator vaccine (control
group).
