1993 French pharma giant
Sanofi begins its pursuit of a
dengue vaccine.2009 Still years away from
launching the vaccine, Sanofi
builds a $398 million plant
outside Lyon to produce it.2011 Sanofi begins its two
Phase III trials of its vaccine,
involving 31,000 children
in 10 countries.December 2015 Now named
Dengvaxia, Sanofi’s vaccine
wins first approvals in Brazil,
Mexico, and the Philippines.February 2016 Eminent
researchers SCOTT HALSTEAD
and Philip Russell publish a paper
in Vaccine arguing Dengvaxia
should not be given to people
who have not had a previous
infection.April 4, 2016 The Philippines
launches the first-ever public
vaccination program against
dengue, targeting 1 million
schoolchildren.April 15, 2016 The World Health
Organization recommends
Dengvaxia for highly endemic
dengue countries.Nov. 29, 2017 Sanofi issues
an “update” on Dengvaxia,
recommending the vaccine no
longer be given to people who
have not had a previous dengue
infection.December 2017 The Philippines
suspends its Dengvaxia program
as well as Sanofi’s ability to
sell the vaccine in the country
and calls for a refund from the
pharma company.March 2019 The Philippines’
Department of Justice indicts
20 individuals, including six
Sanofi executives, for their roles
in the Dengvaxia immunization
program.August 2019 The Philippines
declares a dengue epidemic.
President Duterte says he’s open
to a return of Dengvaxia.A Brief History of the Dengvaxia Scare117
FORTUNE.COM // DECEMBER 2019
which challenged it in a published response.
But it did get the attention of the Strate-
gic Advisory Group of Experts (SAGE), the
WHO-affiliated committee that makes recom-
mendations to the international community
on vaccine use.
SAGE’s pronouncements carry weight.
While governments make their own decisions
about whether to approve a drug or implement
it in a national scheme, many take their cues
from SAGE, as does the all-important vaccine
buyer, GAVI. Because Dengvaxia was geared
toward lower-income countries, SAGE felt
even greater responsibility to get this one right.
“When we first saw the [trial] results, we
were all a bit disappointed,” says Terry Nolan,
who cochaired the SAGE Working Group (he
is now a consultant for Sanofi). “It had definite
effectiveness, but it was modest.” Beyond that,
though, was the question concerning the chil-
dren who had gotten more severe infections.
Was this age-related and limited to younger
kids? Or did it have something to do with
serostatus, as experts like Halstead vociferously
argued, and so older children were also at risk?
In the end, the committee hedged its bets:
SAGE’s experts relied on models that assumed
Dengvaxia was both less effective and more
likely to cause severe disease in kids who’d
never been exposed to a dengue infection. So
SAGE recommended that the vaccine be used
in places where infection rates of dengue in
children were 70% or higher. But Dengvaxia
should not be administered anyplace where
less than half the population had been ex-
posed to dengue. (The modeling projected
vaccination of early adolescents would yield a
10% to 30% reduction in dengue hospitaliza-
tions over 30 years.) The goal was to apply the
vaccine where its benefits would outweigh any
possible risk involved—a challenge given the
lack of quality data about infection rates.
Still, says Nolan, “we were very nervous
about it, and we were very cautious in our ini-
tial recommendation and saying, ‘Look, you’ve
got to monitor this closely.’ ”
Cautious or not, though, the recommenda-
tion was interpreted as an endorsement of the
Filipino government’s Dengvaxia program.
The vast majority of children in the Philip-
pines have experienced at least one dengue
infection by age 9, making them great candi-
dates for the vaccine.
Halstead sniffs at the WHO committee’s
conclusion. (“They sort of gave Sanofi the
green light,” he says.) But he spreads some(^) blame as well to the international dengue