Whooping cough vaccination

What is whooping cough?¹

Whooping cough (pertussis) is an acute, highly contagious respiratory infection, usually caused by Bordetella pertussis. The illness involves at least two weeks of cough, associated with paroxysms, associated whoops or post-cough vomiting. It usually resolves in time but may be associated with complications and death, particularly in infants. It is a significant cause of infant mortality worldwide.

Prior to vaccination, it was endemic in the UK but since being part of the routine vaccination programme, it is much less common. Nevertheless, outbreaks continue to occur, most recently in 2012 in the UK. At this time the vaccination programme was temporarily extended to pregnant women in order to provide protection to newborn babies until their own vaccination schedule begins.

See the separate Whooping cough article for more information on the illness.

Whooping cough vaccination history and epidemiology²

Whooping cough vaccination was introduced in the 1950s. Prior to that, the average annual number of whooping cough notifications exceeded 120,000 annually in the UK.

• By 1972, vaccine uptake was approximately 80% and notifications had fallen to 2,069.

• Coverage fell to about 60% in 1975 and further to 30% by 1978 because of professional and public anxiety concerning the safety and efficacy of the vaccine.

• Major epidemics occurred in 1977 and 1981; 1978 saw over 68,000 notifications and 12 deaths.

• The actual number of deaths due to whooping cough can be estimated to be higher because of the difficulty of recognising cases, particularly in infants.

Increased confidence has once more resulted in increased vaccine uptake. From the mid-1990s, uptake has consistently been over 90%.

Despite good uptake, there was a very large increase in laboratory-confirmed cases of whooping cough in England and Wales in 2011 and 2012. The increase after the second quarter of 2011 was predominantly in adolescents and adults. This increase continued in 2012 and extended to infants aged under 3 months, who are at highest risk of severe complications, hospitalisation and death.

As a consequence of this, in 2012 the Department of Health introduced a temporary vaccination programme for pregnant women at 28-32 weeks of gestation. This was extended in 2014 for at least another five years. Studies have shown that pregnant women mount a good immune response to pertussis vaccines, and this to be an effective method of transferring temporary immunity to the neonate.^{3 4}

The annual report of laboratory-confirmed cases of whooping cough in England reported the incidence of laboratory-confirmed cases of whooping cough in January to March 2022 as:¹

• Children aged under 3 months old, who are targeted by the maternal vaccination programme: no cases of whooping cough in 2022, compared with 0 and 16 cases in the same quarter in 2021 and 2020, respectively.

• Children aged 3–11 months: no cases in 2022, compared with 1 and 11 cases in the same quarter in 2021 and 2020, respectively.

• Children aged between 1–4 years: 2 cases in 2022, compared with 0 and 36 cases in the same quarter in 2021 and 2020, respectively.

• People aged 15 years or older: 7 cases in 2022, compared with 10 and 578 cases in the same quarter in 2021 and 2020, respectively.

• Overall: 9 cases in 2022, compared with 11 and 806 cases in the same quarter in 2021 and 2020, respectively.

Indications²

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 (Hib) as well.

• DTaP/IPV/Hib contains:

  • Diphtheria.

  • Tetanus.

  • acellular Pertussis.

  • Inactivated Polio Vaccine.

  • Haemophilus influenzae type b.

• DTaP/IPV contains:

  • Diphtheria.

  • Tetanus.

  • acellular Pertussis.

  • Inactivated Polio Vaccine.

Primary immunisation

• This is for infants and children under 10 years of age.

• 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 primary vaccination of all infants from 2 months up to 10 years of age.

• Brands used in the UK are Infanrix®IPV+Hib or Pediacel®. Where possible, the same one should be used for all three doses.

Non-standard situations:

• 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 preschool 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 but this is felt unlikely to produce an unacceptable rate of reactions.

• Currently, primary 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 preschool 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.

• At this time they should be given DTaP/IPV.

• Products used in the UK are Infanrix®-IPV or Repevax®.

Non-standard situations:

• 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.

Pregnant women

• Pregnant women should be offered a single 0.5 ml dose of dTaP/IPV vaccine.

• Vaccine should be offered to women in every pregnancy.

• Vaccination should be offered between gestational weeks 16 and 32 to maximise the likelihood that the baby will be protected from birth.

The vaccine²

The acellular vaccines are made from highly purified selected components of the B. 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 incidence of local and systemic reactions is lower with acellular pertussis vaccines than with whole-cell pertussis vaccines.⁵

The acellular vaccine initially 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. Since then it has been established that the three-component vaccine Infanrix®IPV+Hib is as effective, and both are now considered suitable.

As described in the section above, the pertussis vaccines are only given as part of combined products as DTaP/IPV/Hib or DTaP/IPV. Monovalent pertussis vaccine is not available.

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

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

Administration²

The vaccines are mostly supplied as a cloudy white suspension in a pre-filled syringe. The suspension may develop sediment during storage and should be shaken to distribute the suspension uniformly before administration. Infanrix®-IPV+Hib, however, is supplied as the Hib in a powder in a vial and the rest in a suspension in a pre-filled syringe. The vaccine must be reconstituted by mixing the two.

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, usually three years later at the preschool stage.

Route and site

• 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.

• 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 individual's records.

Contra-indications²

There are very few contra-indications to the pertussis vaccine and very few individuals who should not receive it. If in doubt, seek advice rather than withhold administration of the vaccine. The risk to the individual of not being immunised must be taken into account.

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

• A confirmed anaphylactic reaction to a previous dose of a pertussis-containing vaccine

• A confirmed anaphylactic reaction to neomycin, streptomycin or polymyxin B (which may be present in trace amounts).

Confirmed anaphylaxis is very rare. Other allergic conditions are more common but are not contra-indications to further immunisation.

If the individual is acutely unwell the vaccination should be postponed but only if there is fever or systemic upset.

Special circumstances²

• Premature infants should have their immunisations at the appropriate chronological age, according to the schedule. Very premature babies may have a higher risk of apnoea following vaccination and should be monitored in hospital following the first dose.

• Individuals with immunosuppression and HIV infection (whatever the CD4 count) should be given pertussis-containing vaccines as per the routine recommended schedule. These individuals may not make a full antibody response and may require re-immunisation following treatment. 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 the situation is not stable and there is evolving neurological abnormality.

• If there is ongoing 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.

• A family history of seizures is not a contra-indication to immunisation. Where there have been febrile seizures following previous immunisation, this is not a contra-indication, and advice regarding fever prevention and management should be given.

Adverse effects^{2 6}

Pain and inflammation at the injection site are common. A painless nodule may appear at the site, but usually goes spontaneously. Fever occurs less commonly.

Rarely, there may be seizures or episodes or cyanosis or pallor.

Previous concerns about neurological adverse effects were associated with the whole-cell vaccine which is no longer used.