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THE LANCET INFECTIOUS DISEASES/THE LANCET: Press Releases
This release contains content from both The Lancet
and The Lancet Infectious Diseases, please credit
appropriately.
COULD VACCINATION FOR CHILDREN
AGAINST SEASONAL FLU STOP IMMUNITY DEVELOPING AGAINST PANDEMIC
STRAINS?
Infection with “seasonal”
influenza A could actually benefit children by giving them
improved immunity against pandemic strains such as the swine
flu H1N1 strain now circulating. Thus, vaccinating children
aged 6 months to 5 years against seasonal flu, as is recommended
in some countries, could be disadvantageous to these children.
This controversial theory is discussed in a
Personal View published
Online First and in the
December edition of The Lancet Infectious Diseases,
written by
Dr Guus Rimmelzwaan, Erasmus Medical Center, Rotterdam,
Netherlands, and colleagues. In an accompanying comment,
Drs Terho Heikkinen and Ville Peltola, Turku University
Hospital, Turku, Finland, disagree, saying that preventing
children catching seasonal flu is a definite benefit of
vaccination which far outweighs the theoretical risk put
forward by Rimmelzwaan and colleagues.
It has been shown, mainly in animals,
that infection with influenza A viruses can induce protective
immunity to influenza A viruses of other unrelated subtypes.
Rimmelzwaan and colleagues say: “This so-called heterosubtypic
immunity does not provide full protection, but can limit
virus replication and reduce morbidity and mortality of
the host.”
They add that this type of immunity
might be relevant to human beings when a new subtype of
influenza A virus is introduced into the population, such
as the new influenza A H1N1 virus (swine flu) responsible
for the current pandemic; and also potential future pandemics
that may be caused by avian flu subtypes. While avian flu
in humans is still very rare, it does cause high levels
of mortality in those infected.
The authors say: “Preventing
infection with seasonal influenza viruses by vaccination
might prevent the induction of heterosubtypic immunity to
pandemic strains, which might be a disadvantage to immunologically
naive people, such as infants.”
The present pandemic could be a unique
opportunity to investigate heterosubtypic immunity. The
authors say that close monitoring of admissions to hospital
and mortality rates among infants that have received annual
influenza vaccination since birth and comparison with unvaccinated
age-matched children might provide information on the potential
downside of yearly influenza vaccination.
Rimmelzwaan and colleagues conclude:
“The development and use of vaccines that can induce
broad protective immunity might be a solution for these
potential problems and we think this is a priority.”
Importantly,
Rimmelzwaan and colleagues add that they fully support the
forthcoming vaccination programme against H1N1 influenza,
which will reduce severe disease and mortality in all age
groups.
They say*: "Use of these pandemic
influenza vaccines will over-ride the theoretical issues
associated with yearly vaccination against seasonal influenza."
In the linked
Reflection and Reaction
comment, Heikkinen and Peltola say that
“the results of experimental animal studies can never
be extrapolated directly to human beings, let alone form
the basis of any vaccination policy”.
They do agree with Rimmelzwaan and
colleagues on one point-
the need for more effective influenza vaccines that would
also induce broader immune responses.
However, they conclude: “Public
health decisions should be based on the best clinical
evidence available. There is ample evidence for the
great burden of influenza in young children, and this burden
appears during every influenza season. By contrast, there
is no clinical evidence that vaccinating children against
influenza would prevent the induction of heterosubtypic
immunity and thereby be disadvantageous to children in the
long run. While waiting for improved influenza vaccines,
the simple question is should we let young children suffer
from a severe and potentially lethal but easily preventable
illness, just because there is a theoretical possibility
that withholding vaccination might result in a slightly
less severe illness sometime in the future? We believe that
the answer to this question is a simple one.”
Dr Guus Rimmelzwaan, Erasmus Medical Center, Rotterdam,
Netherlands. T) +31-10-7044066
. E)
g.rimmelzwaan@erasmusmc.nl
Ville Peltola,
Turku University Hospital, Turku, Finland. T) please complete
telephone number E)
ville.petola@utu.fi
For full Personal
View and Reflection and Reaction, see:
http://press.thelancet.com/tlidchildvacc.pdf
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