Indications

A minimum of four doses of a pertussis-containing vaccine should be given at appropriate intervals for all individuals up to 10 years of age. The appropriate vaccine for each age group is determined by the need to protect individuals against diphtheria, tetanus, polio and Haemophilus influenzae type b as well.

Primary immunisation

This is for infants and children under 10 years of age.^[1] The primary course of pertussis vaccination consists of three doses of a pertussis-containing product with an interval of one month between each dose:

• DTaP/IPV/Hib is recommended for all infants from 2 months up to 10 years of age.
  • If the primary course is interrupted it should be resumed but not repeated, allowing an interval of one month between the remaining doses.
  • DTaP/IPV/Hib should be used to complete a primary course that has been started with a whole-cell or another acellular pertussis preparation.
  • Children of 1 to 10 years, who have completed a primary course (which includes three doses of diphtheria, tetanus and polio) but have not received three doses of a pertussis-containing vaccine, should be offered a dose of combined DTaP/IPV (or DTaP/IPV/Hib) vaccine to provide some priming against pertussis.
  • They should then receive the first reinforcing dose as scheduled, also as DTaP/IPV (or DTaP/IPV/Hib), preferably allowing a minimum interval of one year.
  • Similarly, children who present first for the pre-school booster without any pertussis, should also receive DTaP/IPV (or DTaP/IPV/Hib) as priming and reinforcing doses, preferably allowing a minimum interval of one year.
• The DTaP/IPV vaccine, which contains a lower dose of pertussis antigen, should only be used as a booster in fully primed children.
• Children of 1 to 10 years, who have completed the primary course plus a reinforcing dose (which includes four doses of diphtheria, tetanus and polio) but have not received four doses of pertussis-containing vaccine, may be offered a dose of combined DTaP/IPV or DTaP/IPV/Hib (if appropriate) to provide some or additional protection against pertussis, preferably allowing an interval of one year from the previous dose. These children will therefore receive an extra dose of diphtheria, tetanus or polio vaccines. Such additional doses are unlikely to produce an unacceptable rate of reactions.^[7]
• Currently, immunisation against pertussis is not recommended for children aged 10 years or over, and adults.

Reinforcing immunisation

• Children under 10 years of age should receive their first pertussis booster combined with diphtheria, tetanus and polio vaccines in their pre-school vaccines. The first booster of pertussis-containing vaccine should ideally be given three years after completion of the primary course, normally between 3 years and 4 months to 5 years of age.
• When primary vaccination has been delayed, this first booster dose may be given at the scheduled visit, provided it is one year since the third primary dose. This will re-establish the child in the normal schedule.
• If a child attends for a booster dose and has a history of receiving a vaccine following a tetanus-prone wound, attempts should be made to identify which vaccine was given. If the vaccine given was the same as that due at the current visit, and at an appropriate interval, then the booster dose is not required. Otherwise, the dose given at the time of injury should be discounted, as it may not provide satisfactory protection against all antigens, and the scheduled immunisation should be given.
• Individuals aged 10 years or over, who have only had three doses of pertussis vaccine, do not need further doses.

The vaccine

The acellular vaccines are made from highly purified selected components of the Bordetella pertussis organism. These components are treated with formaldehyde or glutaraldehyde and then adsorbed on to adjuvants, either aluminium phosphate or aluminium hydroxide, to improve immunogenicity:

• The vaccine chosen for primary immunisation in the UK programme (Pediacel®) contains five purified pertussis components. This vaccine has been shown to offer equal or better protection against clinically typical pertussis disease than the whole-cell pertussis vaccine previously used in the UK.^[8]
• The incidence of local and systemic reactions is lower with acellular pertussis vaccines than with whole-cell pertussis vaccines.^[8]

The pertussis vaccines are only given as part of combined products:

• Diphtheria/tetanus/acellular pertussis/inactivated polio vaccine/Haemophilus influenzae type b (DTaP/IPV/Hib)
• Diphtheria/tetanus/acellular pertussis/inactivated polio vaccine (DTaP/IPV or dTaP/IPV).

The above vaccines are thiomersal-free. They are inactivated and do not contain live organisms and cannot cause the diseases against which they protect. Monovalent pertussis vaccine is not available.

Vaccine efficacy is maximal (but not 100%) immediately after immunisation and wanes gradually thereafter.  It is possible for vaccinated individual to have pertussis, but the illness is usually less severe.

Initiation of treatment

It is supplied as a cloudy white suspension, either in a single-dose ampoule or in a pre-filled syringe. The suspension may develop sediment during storage and should be shaken to distribute the suspension uniformly before administration.

Dosage and schedule

• First dose of 0.5 ml of a pertussis-containing vaccine.
• Second dose of 0.5 ml, one month after the first dose.
• Third dose of 0.5 ml, one month after the second dose.
• A fourth dose of 0.5 ml, given at the recommended interval.

Administration

• Vaccines are routinely given intramuscularly into the upper arm or antero-lateral thigh. This is to reduce the risk of localised reactions, which are more common when vaccines are given subcutaneously.^[9]
• However, for individuals with a bleeding tendency, vaccines should be given by deep subcutaneous injection in order to reduce the risk of bleeding.
• Pertussis-containing vaccines can be given at the same time as other vaccines such as MMR, MenC and hepatitis B. The vaccines should be given at a separate site, preferably in a different limb. If given in the same limb, they should be given at least 2.5 cm apart.
• The site at which each vaccine was given should be noted in the patient's records.

Contra-indications

The vaccines should not be given to those who have had:

• A confirmed anaphylactic reaction to a previous dose of a pertussis-containing vaccine, or a confirmed anaphylactic reaction to neomycin, streptomycin or polymyxin B (which may be present in trace amounts). Confirmed anaphylaxis occurs extremely rarely. Data from the UK, Canada and the USA point to rates of 0.65 to 3 anaphylaxis events per million doses of vaccine given.^[10]
• Other allergic conditions may occur more commonly and are not contra-indications to further immunisation.
• The risk to the individual of not being immunised must be taken into account.

Special circumstances

• Premature infants should have their immunisations at the appropriate chronological age, according to the schedule. There is no evidence that premature babies are at an increased risk of adverse reactions from vaccines.^[11]
• Individuals with immunosuppression and HIV infection (regardless of CD4 count) should be given pertussis-containing vaccines in accordance with the routine recommended schedule. These individuals may not make a full antibody response. Re-immunisation should be considered after treatment is finished and recovery has occurred. Specialist advice may be required.
• If a child has a stable pre-existing neurological abnormality, such as spina bifida, congenital abnormality of the brain or perinatal hypoxic ischaemic encephalopathy, they should be immunised according to the recommended schedule.
• When there has been a documented history of cerebral damage in the neonatal period, immunisation should be carried out unless there is evidence of an evolving neurological abnormality.
• If there is evidence of current neurological deterioration, including poorly controlled epilepsy, immunisation should be deferred and the child should be referred to a child specialist for investigation to see if an underlying cause can be identified.
• If a cause is not identified, immunisation should be deferred until the condition has stabilised.
• If a cause is identified, immunisation should proceed as normal.
• A family history of seizures is not a contra-indication to immunisation.

Adverse effects

• If a child experiences encephalopathy or encephalitis within seven days of immunisation, it is unlikely that these conditions will have been caused by the vaccine and they should be investigated by a specialist.
• Immunisation should be deferred until the condition has stabilised, in children where no underlying cause was found and the child did not recover completely within seven days.
• If a cause is identified or the child recovers within seven days, immunisation should proceed as recommended.
• If a seizure associated with a fever occurs within 72 hours of an immunisation, further immunisation should be deferred until the condition is stable if no underlying cause has been found and the child did not recover completely within 24 hours.
• If a cause is identified or the child recovers within 24 hours, immunisation should continue as recommended.