Pertussis (whooping cough)

What

Pertussis, commonly known as ‘whooping cough’, is a disease of the respiratory tract caused by the bacterium Bordetella pertussis. It is highly infectious in unvaccinated people. In Australia, pertussis epidemics usually occur every 3–4 years.

Who

Acellular pertussis–containing vaccine is recommended for:

• routine vaccination in infants, children and adolescents
• routine booster vaccination in adults, including those in special risk groups or in contact with a special risk group, such as
  • women who are pregnant or breastfeeding
  • healthcare workers
  • early childhood educators and carers
  • people in close contact with infants
• vaccination of people who have missed doses of pertussis-containing vaccine

How

Pertussis-containing vaccines are only available in Australia as combination vaccines that include other antigens such as diphtheria and tetanus.

Pertussis-containing vaccines are recommended for children at 2, 4, 6 and 18 months, and 4 years of age, and adolescents at 11–13 years of age.

Pertussis-containing vaccines are recommended for adults at ages 50 years and 65 years.

Vaccination of pregnant women is recommended during each pregnancy, preferably between 20 and 32 weeks gestation.

Vaccination is recommended every 10 years for healthcare workers, early childhood educators and carers, and people in close contact with infants.

Why

In Australia, in the absence of maternal vaccination, an average of 1 death and more than 200 hospitalisations related to pertussis occurred in infants <6 months of age each year. These infants are too young to be fully immunised. Older children and adults who have not received pertussis vaccination are at risk of infection, and are often the source of infection in infants.

Pertussis vaccines available in Australia

The Therapeutic Goods Administration website provides product information for each vaccine.

See also Vaccine information and Variations from product information for more details.

Dose and route

The dose of all pertussis-containing vaccines is 0.5 mL given by intramuscular injection.

Co-administration with other vaccines

Do not mix DTPa- or dTpa-containing vaccines with any other vaccine in the same syringe, unless specifically registered for use in this way.

Pertussis-containing vaccines can be co-administered with most other vaccines. Vaxelis can be given at the same time as other scheduled vaccines, including MenB vaccines. Pertussis-containing vaccines can be co-administered with influenza vaccines or RSV vaccine (Abrysvo) to pregnant women. There is a small reduction in anti-pertussis antibodies (to filamentous haemagglutinin and pertactin) when RSV vaccine (Abrysvo) and dTpa vaccines are co-administered; however, the clinical significance of this is uncertain and no additional dTpa doses are recommended.^25,26

Nimenrix vaccine contains small amounts of tetanus toxoid. If a person needs to receive Nimenrix and a vaccine containing tetanus toxoid, co-administration of these vaccines is preferred. Giving Nimenrix after a vaccine containing tetanus toxoid may interfere with the immune response against some meningococcal serogroups. There is uncertainty about whether this reduced immune response affects clinical protection, and there are no data on the optimal interval between the vaccines. Therefore, Nimenrix should be given as scheduled, even if it is being given shortly after a vaccine containing tetanus toxoid.

Interchangeability of Pertussis vaccines

If possible, complete the vaccination schedule for pertussis with the same vaccine brand. If this is not possible, use an alternative brand following the dose recommendations. See Recommendations.

Contraindications

The only absolute contraindications to acellular pertussis–containing vaccines are:

• anaphylaxis after a previous dose of any acellular pertussis–containing vaccine
• anaphylaxis after any component of an acellular pertussis–containing vaccine

Precautions

People with latex allergy

The product information for Adacel states that the tip cap of the syringe contains latex. Consider using an alternative product in people with an allergy or sensitivity to latex.

Whole-cell pertussis-containing vaccines are no longer available in Australia.

Pertussis-containing vaccines in children

Acellular pertussis–containing vaccines are associated with a lower incidence of fever (approximately 20%) than whole-cell pertussis–containing vaccines (approximately 45%). Acellular pertussis–containing vaccines are also associated with a lower incidence of local adverse events (approximately 10%) than whole-cell pertussis–containing vaccines (approximately 40%).^27-29 Whole-cell pertussis–containing vaccines are no longer available in Australia.

Local and systemic adverse reactions are more common after hexavalent vaccines than after monovalent vaccines. There is little to no difference in the rates of adverse events after hexavalent vaccines compared with other combination vaccines including other hexavalent vaccines.^30-32

Extensive limb swelling

Extensive limb swelling occurs in <2% of children after booster doses of DTPa.³³ It is defined as swelling and/or redness involving:

• at least half the circumference of the limb
• the joints both above and below the injection site

Extensive limb swelling is not always associated with pain.

Such reactions usually start within 48 hours of vaccination, last for 1–7 days and resolve completely without sequelae.³³

The pathogenesis of extensive limb swelling is poorly understood. One analysis reported entire thigh swelling in 2% of 1015 children who had their 4th and 5th doses using the same brand of DTPa vaccine. All these resolved completely without intervention.³³

A history of extensive limb swelling after a booster dose of pertussis-containing vaccine is not a contraindication to further pertussis-containing vaccine doses during childhood or later in life.³⁴ See Recommendations.

Parents of children about to receive a booster dose of a pertussis-containing vaccine should be told about the small but well-defined risk of extensive limb swelling. They should be told that it is usually not associated with significant pain or limitation of movement, and needs no specific treatment.

Febrile convulsions

Febrile convulsions are reported rarely after receiving an acellular pertussis–containing vaccine, within 48 hours of vaccination. The risk is even lower in infants who complete their primary course at 6 months of age. This is because febrile convulsions are uncommon in children <6 months of age.

Hypotonic-hyporesponsive episodes

A hypotonic-hyporesponsive episode (HHE) is an episode of pallor, limpness and unresponsiveness. It may also include shallow breathing and cyanosis. HHEs occur rarely after receiving a pertussis-containing vaccine, 1–48 hours after vaccination. An HHE may last from a few minutes to 36 hours. In Australia during 2012, 2.2 cases of HHE were reported per 100,000 doses of pertussis-containing vaccine given to children <1 year of age.³⁵ Follow-up of children with HHE shows no long-term neurologic or other sequelae.³⁶

Children who have an HHE after receiving a pertussis-containing vaccine should receive further doses of routinely scheduled pertussis-containing vaccines. They may need medical supervision at the time of vaccination. Contact your state or territory health department for more details about services for adverse events following immunisation.

Other reported adverse events

Pertussis-containing vaccines, including acellular pertussis–containing vaccines, do not cause infantile spasms, epilepsy or encephalopathy.³⁷ Infants and children who have active or progressive neurologic disease, or a family history of a neurologic disorder, can be safely vaccinated with pertussis-containing vaccines.

For infants and children with the following conditions, the risk of adverse events after receiving a pertussis-containing vaccine is the same as for other infants of the same age:

• stable neurologic disease, including cerebral palsy
• family history of idiopathic epilepsy
• other familial neurologic disorders

Sudden infant death syndrome (SIDS) is not associated with pertussis-containing vaccines.³⁸ Some studies suggest a decreased risk of SIDS in children who have been vaccinated.^39-41

Pertussis-containing vaccines in adolescents and adults

Pertussis-containing vaccines are safe and well tolerated in adults when given as a booster dose.^42-45

The incidence of fever is low, and comparable in vaccine and placebo recipients in clinical trials.^42-44

Revaccination of adolescents and adults within 10 years after a tetanus-containing vaccine (dT or dTpa) is associated with:^17-18

• no increase in moderate or severe adverse events
• no increase in subjective fever
• an increase in mild, transient injection site pain

Adverse reactions to a single dose of dTpa vaccine are similar whether a person receives the vaccine shortly after, or at a longer interval after, a previous dT vaccine.^10-13,46

Limb swelling reactions after pertussis-containing booster doses were reported in 1% of adolescent and adult clinical trial participants.^17,18

Some adults have a history of adverse event(s) after receiving a whole-cell pertussis–containing vaccine in childhood. These adults can almost always receive acellular pertussis–containing vaccines, which do not have the same risk of adverse events. See Vaccination for people who have had an adverse event following immunisation. 

Brachial neuritis may occur after receiving pertussis-containing vaccines as a result of the presence of tetanus toxoid. This is inflammation of a nerve in the arm, causing weakness or numbness. The excess risk is approximately 0.5–1 in 100,000 doses in adults.^47,48

dTpa vaccines in pregnant women

Vaccination with dTpa during pregnancy does not increase the risk of adverse pregnancy outcomes. Studies have excluded any association with stillbirth, pre-eclampsia, fetal distress, low birth weight or neonatal renal failure.^49-55

There may be a small risk of significant injection site reactions after repeat vaccine doses in some women who have dTpa vaccines during successive, closely spaced pregnancies. However, a retrospective study of more than 29,000 women who received dTpa vaccine during pregnancy looked at acute adverse events, including fever, allergy and injection site reactions. The risk of these events was similar in women who had received a tetanus-containing vaccine in the previous 5 years and women who had received a dose more than 5 years previously.⁵⁵

Pertussis (whooping cough) is caused by Bordetella pertussis, a fastidious gram-negative pleomorphic bacterium. Other bacteria can also cause a pertussis-like syndrome.⁵⁶ These include B. parapertussis, Mycoplasma pneumoniae and Chlamydophila pneumoniae.

Pathogenesis and transmission

Pertussis is a respiratory infection that spreads by aerosols. It has an incubation period of 7–20 days. It is highly infectious in unvaccinated people, and can infect 90% of susceptible household contacts.⁵⁷

Natural infection does not provide long-term protection. Repeat infection can occur.⁵⁷

Diagnosis

Pertussis infection can be confirmed by either:

• culture or nucleic acid testing of a nasal or throat swab, or nasopharyngeal aspirate specimen, or
• serology

The appropriate diagnostic test depends on age, vaccination history and duration of symptoms. Nucleic acid testing is usually the diagnostic method of choice. Serology can be used to help confirm the diagnosis, but ideally should not be used as the only diagnostic test in someone who has had a pertussis-containing vaccine in the past 5 years.⁵⁸

Symptoms of pertussis

Unvaccinated children can have a characteristic paroxysmal cough with a ‘whoop’ when breathing in. This is less common in people who have immunity as a result of vaccination or infection. ⁵⁹ In very young infants, the cough may be minimal or absent, and the only symptoms may be apnoea or cyanosis.

Each year, more than 25% of adults have a cough that lasts at least 5 days. Bordetella pertussis may cause up to 7% of these illnesses.⁶⁰ Patients and physicians may not be aware of the disease, and diagnostic tests sometimes have limited sensitivity. Because of this, pertussis is likely to be underdiagnosed (see Public health management).

Complications of pertussis

Complications in infants include pneumonia, seizures and hypoxic encephalopathy. These complications can lead to death.⁵⁹ The case-fatality rate in unvaccinated infants <6 months of age, in the absence of maternal vaccination, is 0.8%.^61,62

Pertussis can also cause significant morbidity in children and adults. The cough can persist for up to 3 months. Other significant symptoms can include:⁶³

• sleep disturbance
• urinary incontinence
• fainting
• rib fracture (rarely)

Death from pertussis is rare in people aged 10–70 years.

Pertussis is the second most frequently notified vaccine preventable disease in Australia.⁶⁴ Despite a longstanding pertussis immunisation program, and a substantial decline in morbidity and mortality from the disease, prior to the COVID-19 pandemic pertussis outbreaks occurred every few years.⁶⁵

Between 2013 and 2018 there were 91,780 notifications of pertussis in Australia. The average annual all-age national notification rate was 63.6 per 100,000 population, a 40% reduction compared to the previous 6 years (2006–2012) which was 103.1 per 100,000 population.⁶⁴ Pertussis notifications decreased significantly between 2020 and 2022, and this decrease has been attributed to the COVID-19 outbreak mitigation measures that were in place during that time.⁶⁶ The risk for future pertussis outbreaks still remains and ongoing vaccination is important.

Risk of pertussis by age

Pertussis severity varies with age and immunisation status. Unimmunised infants who are too young to be fully immunised have the highest risk of hospitalisations and deaths.⁶⁷

Between 2013 and 2018, the highest notification rates were in children aged 9–11 years, followed by children aged 3 years. Since the introduction of maternal pertussis occur in this vaccination during pregnancy in 2015, pertussis notification rates significantly decreased in infants <2 months of age and the 6–11 months age group.⁶⁴ Although the incidence in infants <2 months of age has been progressively decreasing from 2015, hospitalisation rates remain highest for this age group. Notification rates are higher among Aboriginal and Torres Strait Islander children compared to non-Indigenous children across all age groups <5 years. Among people ≥5 years of age, people aged ≥65 years have the highest rate of hospitalisation.⁶⁴

In highly immunised communities, pertussis can occur in adults and adolescents as a result of waning immunity.^68,69 These people are a significant reservoir of infection. Household contacts and carers are often the source of infection in infants. Parents are the source in more than 50% of cases.²⁴ Siblings are also a significant source of infant infections.^4,5 Young infants can also acquire the disease from healthcare workers.^20-23

Pertussis vaccine is only available in Australia in combination with diphtheria and tetanus. Vaccines may also include inactivated poliovirus, hepatitis B and Haemophilus influenzae type b.

The acronym DTPa, using capital letters, signifies a child formulation of diphtheria, tetanus and acellular pertussis–containing vaccine.

The acronym dTpa signifies a formulation that contains substantially less diphtheria toxoid and pertussis antigens than the child formulation. Adolescents and adults are recommended to receive dTpa vaccine.

Pertussis vaccines used in Australia

Acellular pertussis–containing vaccines registered in Australia contain 2 or more purified components of Bordetella pertussis:

• The 3-component vaccines also include pertactin (PRN).
• The 5-component vaccines also include 2 fimbrial (FIM) antigens.

Vaccine effectiveness in children

Pertussis-containing vaccines protect against severe and typical pertussis. They provide substantially less protection against milder coughing illness.^27,28 DTPa vaccines with 3 or more antigens have vaccine efficacy of:²⁸

• 71–78% for preventing milder symptoms of pertussis (≥7 days of paroxysmal cough and laboratory confirmation)
• 84% for preventing typical disease (≥21 days of paroxysmal cough and laboratory confirmation)

The 1st dose of the childhood schedule significantly reduces the incidence of severe pertussis disease in young infants.^1,70-72 Protection increases further with the doses given at 4 and 6 months of age, as measured by hospitalisation rates and mortality.

Duration of immunity in children

Immunity after receiving a pertussis-containing vaccine wanes over time. In Australian children aged 1–3 years who had not had an 18-month booster dose, the effectiveness of 3 doses of pertussis-containing vaccine declined progressively from 2 years of age, to less than 50% by 4 years of age.³ Studies in older children suggest that vaccine effectiveness decreases with time since the dose of pertussis-containing vaccine given before starting school.^7,8,73

Vaccine effectiveness in adolescents and adults

Pertussis-containing vaccines with reduced antigen content (dTpa) are immunogenic, including in older people.^42,74-76 A randomised trial in adults reported a point estimate of 92% efficacy against culture-positive or nucleic acid test–positive disease within 2.5 years of vaccination with a 3-component monovalent pertussis vaccine.⁶⁰

Duration of immunity in adolescents and adults

Data on the duration of immunity to pertussis after a single booster dose of dTpa are limited. Long-term follow-up of adults showed a rapid decline in pertussis antibody levels within 2 years after vaccination. This decline continued steadily to 10 years after vaccination, although antibody levels remained above baseline.¹⁷

Long-term follow-up of adolescents showed a more rapid decline. Pertussis antibody levels decreased to, or approached, pre-vaccination levels after 10 years.¹⁸ The rate of decline in clinical protection is unknown, but some protection against clinical disease may persist for up to 10 years.

Vaccine effectiveness in infants of vaccinated pregnant women

Vaccinating pregnant women with dTpa can reduce the risk of pertussis in them and their young infants. This is a result of direct passive protection by transplacental transfer of high levels of pertussis antibodies from the mother to the fetus during pregnancy.

Vaccination of pregnant women before delivery has been reported to reduce pertussis disease in infants by 80-91%.^77,78 However, it is not known:

• what exact level of pertussis antibody the pregnant woman needs to have to provide this level of protection to her infant
• how waning pertussis immunity in the mother affects this protection

Duration of immunity in infants of vaccinated pregnant women

Some studies suggest that pertussis antibody levels in the mother decline progressively in the year after delivery. ^79,80 In another study, pertussis antibody levels were detectable in both mothers and their infants at the time of delivery, even though the mothers were vaccinated around 13 months earlier (pre-pregnancy).⁸¹

In some studies, children born to women who were vaccinated with dTpa during pregnancy had lower levels of pertussis antibodies a month after completing infant vaccination than children of mothers who were not vaccinated.^82-85 But antibodies reached the same level after another dose at 12–18 months of age, regardless of whether the child’s mother was vaccinated during pregnancy.⁸² A more recent multi-centre cohort study in the UK showed similar findings. Results showed that prior to a booster dose, levels of anti-pertussis toxin antibodies were lower in children born to vaccinated mothers, but no such difference was seen after the booster dose (given at 3 years 4 months of age).⁸⁶ A recent Canadian observational cohort study compared post booster IgG levels in children born to vaccinated mothers and non-vaccinated mothers, taking into account the infant schedule received. There was some evidence of a reduction in antibody response to a booster dose in the vaccinated group following a 2+1 schedule, but not after a 3+1 schedule, noting the absolute difference in antibody titres was very small.⁸⁷

Pertussis vaccine for household contacts of infants

Cocoon vaccination means vaccinating household contacts and carers, who are an important source of pertussis infection. This is an alternative vaccination strategy that may reduce the infection risk to infants, especially young infants.²⁴ Vaccination of both parents is estimated to reduce the risk of infant pertussis by 51% (95% CI: 10–73%).^19,88

Transport according to National Vaccine Storage Guidelines: Strive for 5.⁸⁹ Store at +2°C to +8°C. Do not freeze. Protect from light.

Infanrix hexa vaccine must be reconstituted. Add the entire contents of the syringe to the vial and shake until the pellet completely dissolves. Use the reconstituted vaccine as soon as practicable. If it must be stored, hold at room temperature for no more than 8 hours.

Pertussis (both suspected and confirmed) is a notifiable disease in all states and territories in Australia.

The Communicable Diseases Network Australia national guidelines for pertussis⁹⁰ have details about the management of pertussis cases and contacts.

State and territory public health authorities can also provide advice.

Suspected cases of pertussis should be investigated, regardless of vaccination status. This is because immunisation is not 100% effective and immunity wanes over time.

Managing suspected pertussis

People with suspected pertussis infection should receive appropriate antibiotic therapy if coryza started less than 21 days ago.

Antibiotic treatment does not shorten the course of the illness, but antibiotics reduce infectivity if given early, and reduce the risk of transmitting Bordetella pertussis. Details about appropriate macrolide antibiotics and dosing are in the national guidelines for pertussis ⁹⁰ and Therapeutic Guidelines: Antibiotic.⁹¹

Managing contacts of cases

Vaccination

Vaccination in response to an outbreak does not help control the outbreak, even in closed settings.

However, unvaccinated or partially vaccinated contacts should receive:

• DTPa-containing vaccines if they are <10 years of age
• dTpa-containing vaccines if they are ≥10 years of age

See also Catch-up vaccination.

Passive immunisation with normal human immunoglobulin does not prevent pertussis.

Chemoprophylaxis

Only high-risk close contacts of cases should receive chemoprophylaxis. The benefit of chemoprophylaxis in preventing transmission is limited by: ⁹²

• delayed clinical presentation
• delayed diagnosis
• imperfect compliance

Recommendations about chemoprophylaxis for close contacts are in the national guidelines for pertussis.⁹⁰

Routine vaccination in children and adults

Infanrix

The product information for Infanrix states that this vaccine is for:

• primary immunisation of infants aged between 2 months and 12 months
• booster dose in children aged 15 months to 6 years who have previously been vaccinated against diphtheria, tetanus and pertussis

The Australian Technical Advisory Group on Immunisation (ATAGI) recommends that Infanrix may also be used for catch-up of the primary schedule or as a booster in children <10 years of age. ATAGI also recommends that the primary schedule can start at 6 weeks of age.

Infanrix hexa

The product information for Infanrix hexa states that this vaccine is for:

• primary immunisation of infants from the age of 6 weeks
• booster dose in children 18 months of age if they need boosting for all antigens

ATAGI recommends that Infanrix hexa may also be used for catch-up of the primary schedule or as a booster in children <10 years of age.

Vaxelis

The product information for Vaxelis states that this vaccine is for:

• primary immunisation of infants from the age of 6 weeks
• a booster dose at least 6 months after the last priming dose

ATAGI recommends that Vaxelis may also be used for catch-up of the primary schedule or as a booster in children <10 years of age.

Infanrix IPV

The product information for Infanrix IPV states that this vaccine is for:

• use in a 3-dose primary schedule for immunisation of infants from the age of 6 weeks
• a single booster dose in children ≤6 years of age who have previously been vaccinated against diphtheria, tetanus, pertussis and poliomyelitis

ATAGI recommends that Infanrix IPV may also be used for catch-up of the primary schedule or as a booster in children <10 years of age.

Quadracel

The product information for Quadracel states that this vaccine is for:

• use in a 3-dose primary schedule from the age of 2 months to 12 months
• booster dose in children from 15 months to 6 years of age who have previously been vaccinated against diphtheria, tetanus, pertussis and poliomyelitis

ATAGI recommends that Quadracel may also be used for catch-up of the primary schedule or as a booster in children aged <10 years. ATAGI also recommends that the primary schedule can start at 6 weeks of age.

Tripacel

The product information for Tripacel states that this vaccine is for:

• use in a 3-dose primary schedule from the age of 2 months to 12 months
• booster dose in children from 15 months to 8 years of age who have previously been vaccinated against diphtheria, tetanus and pertussis

ATAGI recommends that Tripacel may also be used for catch-up of the primary schedule or as a booster in children aged <10 years. ATAGI also recommends that the primary schedule can start at 6 weeks of age.

Adacel and Boostrix

The product information for Adacel (reduced antigen content dTpa) states that this vaccine is for use in people aged ≥10 years for booster doses. Adacel can be used for repeat vaccination, after a previous dose of dTPa or dTPa-IPV to boost immunity to diphtheria, tetanus and pertussis at 5 to 10 year intervals.

The product information for Boostrix (reduced antigen content dTpa) states that this vaccine is for use in people aged ≥4 years for booster doses only.

ATAGI recommends that, when an adolescent or adult receives a 3-dose primary course of diphtheria/tetanus toxoids:

• dTpa should replace the 1st dose of dT
• the 2nd and 3rd doses should be dT

If dT is not available, dTpa can be used for all 3 primary doses.

The product information for Adacel and Boostrix states that there is no recommendation about the frequency of vaccination against pertussis in adults. ATAGI recommends that adults in contact with infants and/or at increased risk from pertussis should have received a vaccine within the past 10 years.

Adacel Polio, Boostrix and Boostrix-IPV

The product information for Adacel Polio, Boostrix and Boostrix-IPV states that vaccine is for use in people aged ≥4 years for booster doses only.

ATAGI recommends that Adacel Polio, Boostrix and Boostrix-IPV should not be used in people aged <10 years, except in certain circumstances.

Vaccination during pregnancy

The product information for Boostrix states that the vaccine may be considered during the 3rd trimester of pregnancy when the possible advantages outweigh the possible risks for the fetus.

The product information for Boostrix states that there is no recommendation about vaccination against pertussis in subsequent pregnancies.

ATAGI recommends that pregnant women receive a dose of pertussis-containing vaccine during each pregnancy, preferably between 20 and 32 weeks gestation.

Vaccination after tetanus-containing vaccines

The product information for Adacel, Boostrix and Boostrix-IPV states that people should not receive dTpa-containing vaccine within 5 years of a tetanus-containing vaccine.

ATAGI recommends that, if the person needs protection against pertussis, they can receive a dTpa-containing vaccine at least 4 weeks after a dT-containing vaccine.

Contraindications

The product information for all pertussis-containing vaccines states that these vaccines are contraindicated in children with the following Acute Neurological Disorders:

• encephalopathy (e.g. coma, decreased level of consciousness, prolonged seizures) occurring within 7 days after a previous dose of a pertussis-containing vaccine dose
• Progressive neurologic disorder, including infantile spasms, uncontrolled epilepsy, progressive encephalopathy.

ATAGI recommends that the only contraindications are:

• anaphylaxis after a previous dose of any acellular pertussis–containing vaccine
• anaphylaxis after any vaccine component of an acellular pertussis–containing vaccine

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