- Scientists have called for an urgent review of the safety
of yellow fever vaccine which is routinely given to travelers heading for
Africa and South America, following the deaths of six people within days
- Millions of people have been vaccinated against the disease
with no ill effects. The jab used to be considered one of the safest of
the vaccines which are made from a weakened form of the virus itself.
- But reports published in this week's Lancet have revealed
the deaths of a five-year-old girl and a 22-year-old woman in Brazil, three
elderly people in the US and a 56-year-old man in Australia as a result
of immunization. One other man in the US nearly died.
- While scientists stressed that travelers must continue
to be vaccinated because the disease kills half of those who pick it up,
they said that new research is needed to identify why certain people can
become sensitized to the vaccine.
- Scientists investigating the Brazilian cases said universal
vaccination should be stopped with only those in the areas where yellow
fever is endemic receiving the jab. Those in the USA said doctors should
be careful to give the vaccination only if the traveler is definitely planning
to visit a yellow fever zone, particularly if they are elderly.
- Two separate papers in the Lancet - on the Brazilian
cases and the US cases - and a research letter on the Australian case,
identify the vaccine as the cause of death.
- The victims all suffered some symptoms of yellow fever,
including fever, muscle pain and headache. The elderly Americans, however,
rapidly progressed to multisystemic illness, affecting the liver, kidneys,
lungs and central nervous system.
- The Brazilian team, led by Pedro da Costa Vasconcelos
of the world health organization collaborating centre for reference and
research on arbovirus in Belem, Brazil, said that the five- year-old girl
and 22-year-old woman suffered fever which progressed to jaundice, kidney
failure, low blood pressure and shock. They died around the fifth day after
- The scientists said that they could not be certain that
some other infection had not contributed to the illness and death. Given
that around 2m people received the same vaccine lots, "idiosyncratic
host factors" could be to blame. "These serious and hitherto
unknown complications of yellow fever vaccination are extremely rare, but
the safety [of the vaccine] needs to be reviewed," they wrote.
- The four Americans affected, three of whom died, were
all vaccinated because they planned to tour what they thought were yellow
fever areas. The man who survived was wrongly given the jab before traveling
to Nepal and Thailand.
- Michael Martin and his colleagues from the national center
for infectious diseases in Atlanta, Georgia, said it was possible that
age was a factor in the deaths - the American cases were aged from 63 to
79. But the people who died in Brazil were younger, suggesting age was
not the only factor.
- The cases reported in the Lancet, "along with the
growing momentum for mass immunization in the wake of increased yellow
fever activity, underscore the importance of further investigations"
into the safety of the vaccine, they said.
- The Australian who died had not been outside New South
Wales in the 12 months before he became ill but, said Raymond Chan from
the South Wales area pathology service in Australia, he died from yellow
fever due to infection from the vaccine.