Greenbook notes: Pertussis (Whooping cough) vaccine

Pertussis vaccine

• The pertussis vaccine is thiomersal-free & not a live vaccine.
• It is an acellular vaccine prepared from purified components of B pertussis, treated with formaldehyde/glutaraldehyde and adsorbed onto adjuvants (aluminium hydroxide/aluminium phosphate) to improve immunogenicity.
• Components of B pertussis vary from vaccine to vaccine – usual components are – pertussis toxoid, filamentous haemagglutinin, pertactin, fimbrial agglutinogens etc.

Pertussis vaccine is only given as a part of a combined vaccine. Monovalent pertussis vaccines are not available.

• DTaP/IPV/Hib/HepB (6 in 1) – for primary immunisation
• dTaP/IPV or DTaP/IPV (4 in 1) – preschool booster
• dTaP/IPV – for pregnant women

Vaccines are stored at +2˚C to +8˚C, protected from light.

Excess heat – reduces potency and shelf-life.
Excess cold/freezing – increases reactogenicity and loss of potency; it may also cause hairline cracks on the ampoule leading to contamination.

Contraindication

Confirmed anaphylactic reaction to a previous dose of pertussis-containing vaccine or to any component of the vaccine, including neomycin or polymyxin.

These adverse effects, if they occurred after a vaccine dose, are NOT a contraindication for further vaccination (as they may not recur):

• fever, irrespective of its severity
• hypotonic-hyporesponsive episodes (HHE)
• persistent crying or screaming for more than three hours
• severe local reaction, irrespective of the extent

Adverse effects

• Local reaction – Pain, swelling or redness at the injection.
• Fever, convulsions, high-pitched screaming and episodes of pallor, cyanosis and limpness (HHE).
• Anaphylaxis

Other adverse effects – Whole-cell pertussis vaccine (not currently used acellular vaccine) was reported to have a rare adverse effect – severe acute neurological illness in children.

Other adverse effects that were previously associated with the pertussis vaccine but no causal relationship was found in studies – infantile spasms, hypsarrhythmia, Reye’s syndrome and sudden infant death syndrome.

Immunisation in children

• Primary immunisation – 3 doses, 1 month apart, between 2 months and 10 years.
• As per the national immunisation schedule – it is given @ 8 weeks, 12 weeks and 16 weeks.

A reinforcement/booster dose – should be given 3 years after the primary immunisation, which is @ 3 years and 4 months of age. This is the preschool booster.

If a child presents with a history of vaccine before the booster due to another indication, e.g.tetanus, prone injury, try to establish the vaccine type. If it was given at appropriate intervals and the vaccine is the same type as the booster vaccine, the preschool booster is not needed.

Variations

Premature infants

Premature infants born ≤ 28 weeks of gestation should have their first vaccination in the hospital and be monitored for apnoea, bradycardia or desaturations. If any such event occurs, 2nd vaccination should be given in the hospital as well.

Neurological condition

It (spina bifida, epilepsy, congenital abnormality of the brain or perinatal hypoxic-ischaemic encephalopathy) is not a contraindication.

• If the condition is stable, immunise as normal.
• If deteriorating/not stable (including poorly controlled epilepsy), defer immunisation & refer to paediatrics/ paediatric neurologist. If the cause is identified, immunise. If not identified – defer.
• If the child recovers completely within 7 days – immunise. If not, defer and investigate.
• Immunise once the condition stabilises.

If a child develops encephalopathy within 7 days of immunisation, follow the above plan. If the cause is identified or recovers within 7 days, continue with vaccination; if not, defer and investigate.

If a child develops a febrile seizure within 72 hours of immunisation, continue with immunisation if the cause is identified or recovers within 24 hours; if not, defer and investigate.

Pertussis vaccination programme for pregnant women

This temporary immunisation programme for pregnant women was started in 2012 after a significant increase in the number of pertussis cases, mainly in adolescents and young adults. The highest risk of serious disease was still in infants <3 Months old, hence this booster vaccination in pregnancy would help pass the antibody generated by the mother to the infants before they receive their first vaccine dose at 8 weeks of age. This booster dose should be given in each pregnancy, regardless of previous immunisation, booster during a previous pregnancy or a history of natural infection.

Evaluation of pertussis vaccine in pregnant women found it safe.

[Donegan, 2014][BNF][UKHSA, 2021][Greenbook Ch 24]

Regimen

• The optimal time for vaccination is between weeks 28 and 32 of pregnancy.
• It could be given from 16 weeks onwards as per a recent recommendation. PHE recommends it should be given after the first anomaly scan (18-20 weeks) to avoid any unnecessary association with complications.
• It takes 2 weeks to generate the optimum level of antibody.
• It can be given up to 38 weeks; however, at later stages, the response might not be optimum as the vaccine may fail to generate adequate antibodies before birth, especially in cases of premature birth.
• If a pregnant woman received a pertussis-containing vaccine just before 16 weeks for any reason (e.g. occupational), give a booster as per the programme. If she received it after 16 weeks – that can be counted as a booster.

Boostrix-IPV ((dTaP/IPV) is the vaccine used for this programme.

Those women who have not received their vaccine during pregnancy can have the booster in the first two months after childbirth (until the infant receives their first vaccine). It will protect the baby indirectly by protecting the mother.