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While we agree with Adam Finn and Frank Bell that it is an opportune
moment to review the UK policy on the use of pertussis vaccines, we cannot
agree with their conclusion(1). Although there is indeed ample evidence
that in older children adverse events are less common after the acellular
than after the whole cell vaccine(2), this difference becomes less
significant when the vaccine is given at 2, 3 and 4 months as in the UK.
Miller et al.(3) showed that using the current UK schedule, of the
relatively minor reactions, only fever was significantly commoner in those
receiving the whole cell vaccine, whereas in older children other
mild/moderate reactions were also significantly more common. The study
performed by Bell and colleagues(4) only looked at relatively minor
adverse events such as local reactions and fever. The study cited by Finn
and Bell as showing a difference in incidence of febrile seizures and
hypotonic-hyporesponsive episodes was, we assume, conducted at 2, 4 and 6
months(5), as is the norm for Canada. These results cannot therefore be
extrapolated to the UK schedule where one would expect a lesser
difference, if any, between the two sorts of pertussis vaccines.
In considering the use of any vaccine, it goes without saying that
the efficacy of the vaccine should also be taken into account, but this
seems to have been overlooked in the present discussion. The whole cell
vaccines used in the UK have been shown to be more efficacious than all
but the 5 component acellular vaccines(6). (This latter is not available
in the UK.) While pertussis still kills children in the UK, this is an
important consideration(7,8). Uptake of whole cell vaccine is currently
94% overall (9) and there is no evidence to suggest that by adopting an
acellular vaccine, the number of children being immunised would increase.
If this turns out to be true in practice, there would, in effect, be a
reduction in protection afforded to the community. Before this can be
accepted it would have to be shown that there was a substantial gain in
terms of fewer side efects. We are not convinced this has been done.
The voice in the wilderness is not always wrong and we should resist
the temptation to change our policy just to conform.
References
1.Finn A, Bell F. time to switch from whole cell to acellular
pertussis vaccines? BMJ 2000;320:975.
2. Brown F, Greco D, Mastrantonio P, Salmaso S, Wassilak S. Pertussis
vaccine trials.Developments in Biological Standardisation, Vol 89, 1997.
3. Miller E, Ashworth L, Redhead K, Thornton C, Wraight P, Coleman T.
Effect of schedule on acellular and whole-cell pertussis vaccines: value
of laboratory tests as predictors of performance. Vaccine 1997;15:51-60.
4. Bell F, Heath P, MacLennan J, Shackley F, Shearstone N, Diggle L, et
al. Adverse effects and sero-responses to an acellular
pertussis/diphtheria/tetanus vaccine when combined with Haemphilus
influenzae type b vaccine in an accelerated schedule. European Journal of
Pediatrics 199;158:329-36.
5. Scheifele D W, Halperin S A, Pless R, Delage G, Jadavji T, Vaudry W, et
al. Marked Reduction in Febrile Seizures (FSz) and Hypotonic-
Htporesponsive episodes (HHE) with Acellular Pertussis-Based Vaccines;
Results of Canada-Wide Surveillance, 1993-98. Clinical Infectious Diseases
1999;29:966.
6. Elliman D. Whooping cough vaccines: where next? Child:Care Health and
Development 1998;24(4):259-65.
7. Ranganatham S, Tasker R, Booy R, Habibi P, Nadel S, Britto J. Pertussis
is increasing in unimmunised infants; is a change in policy needed?
Archives of Diseases in Childhood 1999;80:297-9.
8. Van Buynder P G, Owen D, Vurdien J E, Matthews R C, Miller E.
Bpordatella pertussis surveillance in England and Wales: 1995-7.
Epidemiology and Infection 1999;123:403-11.
9. Communicable disease Surveillance Centre. COVER programme: October to
December 1999. Communicable Disease Review 2000;10(12):109-10.
Competing interests:
No competing interests
01 April 2000
David Elliman
Consultant & Senior Research Fellow
Helen Bedford
St George's Hospital & The Institute of Child Health, London
Time to switch from whole cell to acellular pertussis vaccines? Perhaps not.
While we agree with Adam Finn and Frank Bell that it is an opportune
moment to review the UK policy on the use of pertussis vaccines, we cannot
agree with their conclusion(1). Although there is indeed ample evidence
that in older children adverse events are less common after the acellular
than after the whole cell vaccine(2), this difference becomes less
significant when the vaccine is given at 2, 3 and 4 months as in the UK.
Miller et al.(3) showed that using the current UK schedule, of the
relatively minor reactions, only fever was significantly commoner in those
receiving the whole cell vaccine, whereas in older children other
mild/moderate reactions were also significantly more common. The study
performed by Bell and colleagues(4) only looked at relatively minor
adverse events such as local reactions and fever. The study cited by Finn
and Bell as showing a difference in incidence of febrile seizures and
hypotonic-hyporesponsive episodes was, we assume, conducted at 2, 4 and 6
months(5), as is the norm for Canada. These results cannot therefore be
extrapolated to the UK schedule where one would expect a lesser
difference, if any, between the two sorts of pertussis vaccines.
In considering the use of any vaccine, it goes without saying that
the efficacy of the vaccine should also be taken into account, but this
seems to have been overlooked in the present discussion. The whole cell
vaccines used in the UK have been shown to be more efficacious than all
but the 5 component acellular vaccines(6). (This latter is not available
in the UK.) While pertussis still kills children in the UK, this is an
important consideration(7,8). Uptake of whole cell vaccine is currently
94% overall (9) and there is no evidence to suggest that by adopting an
acellular vaccine, the number of children being immunised would increase.
If this turns out to be true in practice, there would, in effect, be a
reduction in protection afforded to the community. Before this can be
accepted it would have to be shown that there was a substantial gain in
terms of fewer side efects. We are not convinced this has been done.
The voice in the wilderness is not always wrong and we should resist
the temptation to change our policy just to conform.
References
1.Finn A, Bell F. time to switch from whole cell to acellular
pertussis vaccines? BMJ 2000;320:975.
2. Brown F, Greco D, Mastrantonio P, Salmaso S, Wassilak S. Pertussis
vaccine trials.Developments in Biological Standardisation, Vol 89, 1997.
3. Miller E, Ashworth L, Redhead K, Thornton C, Wraight P, Coleman T.
Effect of schedule on acellular and whole-cell pertussis vaccines: value
of laboratory tests as predictors of performance. Vaccine 1997;15:51-60.
4. Bell F, Heath P, MacLennan J, Shackley F, Shearstone N, Diggle L, et
al. Adverse effects and sero-responses to an acellular
pertussis/diphtheria/tetanus vaccine when combined with Haemphilus
influenzae type b vaccine in an accelerated schedule. European Journal of
Pediatrics 199;158:329-36.
5. Scheifele D W, Halperin S A, Pless R, Delage G, Jadavji T, Vaudry W, et
al. Marked Reduction in Febrile Seizures (FSz) and Hypotonic-
Htporesponsive episodes (HHE) with Acellular Pertussis-Based Vaccines;
Results of Canada-Wide Surveillance, 1993-98. Clinical Infectious Diseases
1999;29:966.
6. Elliman D. Whooping cough vaccines: where next? Child:Care Health and
Development 1998;24(4):259-65.
7. Ranganatham S, Tasker R, Booy R, Habibi P, Nadel S, Britto J. Pertussis
is increasing in unimmunised infants; is a change in policy needed?
Archives of Diseases in Childhood 1999;80:297-9.
8. Van Buynder P G, Owen D, Vurdien J E, Matthews R C, Miller E.
Bpordatella pertussis surveillance in England and Wales: 1995-7.
Epidemiology and Infection 1999;123:403-11.
9. Communicable disease Surveillance Centre. COVER programme: October to
December 1999. Communicable Disease Review 2000;10(12):109-10.
Competing interests: No competing interests