Top Tips: Pertussis

Dr Toni Hazell Offers Five Top Tips for Primary Care Covering the Latest Guidance on When to Suspect Pertussis, How to Manage It, and Public Health Aspects of the Condition

Pertussis, colloquially known as whooping cough, is caused by the bacterium Bordetella pertussis.¹ Similarly to measles, pertussis was endemic in the UK before vaccination, with over 120,000 cases per year in England and Wales.¹ This number plummeted when immunisation was introduced in the 1950s, but a subsequent lack of confidence in the vaccine led to outbreaks in the late 1970s and early 1980s.¹ 

Unfortunately, the UK is again in a position where many people are turning down the potentially life-saving intervention of vaccination, and preventable diseases are becoming more prevalent. In the whole of 2023, there were 858 laboratory-confirmed cases of pertussis; this has already been overtaken by the 4793 cumulative total cases in England between January and April 2024.² If diagnoses continue to rise at this rate, cases in 2024 may be ten times those in 2023.

This article provides five top tips for primary care on uptake of pertussis vaccination and its importance in pregnant women, the clinical presentation and treatment of pertussis, and how and when to report and refer cases of pertussis.

1. Understand the Importance of Pertussis Vaccination

Vaccination against pertussis is given at 8, 12, and 16 weeks of age, with a preschool booster at 3 years and 4 months.³ Vaccine uptake in the UK has been at least 92% since 1992; however, in 2011/12, despite maintenance of vaccine uptake, there was an outbreak of pertussis in England and Wales among infants, adolescents, and adults.¹ This was partly attributed to the fact that protection after vaccination decreases over time, affecting herd immunity.^1,4 This is a particular concern for newborns, who are too young to be vaccinated, and rely upon the transfer of maternal antibodies across the placenta for protection in the first weeks of life.⁵ In 2012, this was addressed with the introduction of a pertussis vaccination given from 16 weeks of pregnancy.⁵ This is a hugely effective intervention, offering around 90% effectiveness against confirmed pertussis in an infant, and 97% effectiveness against death from pertussis under the age of 3 months.⁶

It is therefore disappointing that uptake is less than ideal, running at around two-thirds in 2022/23.⁷ Uptake is lowest in London, with the next lowest area being the North West of England.^7,8 GPs who are approached by patients with concerns about vaccination during pregnancy may wish to point them to the public-facing page about this subject on the website of the Oxford Vaccine Group.⁹

2. Address Vaccine Hesitancy and Safety Concerns

Whereas it is fear of autism that prevents parents from giving their children the measles, mumps, and rubella vaccine,¹⁰ concerns about the pertussis vaccine arose following a claim that it could cause brain damage in young children.¹¹ These concerns started in the 1970s, and caused vaccination rates to drop from 78.5% in 1971 to 37% in 1974 (England and Wales), with the predictable consequence of a serious pertussis outbreak in 1978/79.¹¹ Parents whose children have or are suspected of having a neurological condition may therefore be nervous about vaccinating, but the Green book offers reassurance, reviewing the evidence in this area and concluding that many cases of encephalopathy that were attributed to the pertussis vaccine turned out to be children with undiagnosed Dravet syndrome—a rare genetic condition that presents with seizures, encephalopathy, and developmental delay.^1,12 

It is those who are hesitant about vaccination, rather than full-on vaccine deniers, who present the best opportunity to change opinion.¹³ People who point to the waning of vaccine protection as a reason not to bother with vaccination can be reassured that pertussis in a previously vaccinated person is less severe.¹⁴ 

Adverse Reactions and Contraindications to the Pertussis Vaccine

Although it is possible (but rare) to develop an acute neurological illness as a reaction to the whole-cell pertussis vaccine, most children in whom this has occurred experienced no long-term harm.¹ In any case, the whole-cell vaccine is not used in the UK, where the safer acellular vaccine is given instead.¹⁵ The risk of febrile seizures from the acellular vaccine is less than 1 in 10,000, and febrile seizures generally have no long-term consequences.¹⁵ Around three or four children in 10,000 will have a hypotonic hyporesponsive episode after vaccination, when the child becomes pale and limp for a short period but quickly recovers.^15,16 Although this is extremely frightening for parents, there are no long-term consequences, and this does not generally recur with subsequent doses, so the course of vaccination can be completed.^15,16 It is not possible to catch pertussis from the vaccine; however, it is possible to develop neurological complications from catching pertussis, which include seizures and cerebral hypoxia.^1,17

GPs are sometimes asked whether a particular child who has been brought for vaccination can safely have it that day. There are very few absolute contraindications, apart from obvious ones such as confirmed anaphylaxis to a previous dose or to certain drugs that may be present in trace amounts in the vaccine (neomycin, streptomycin, and polymyxin B).¹ Children with a stable neurological condition can be safely vaccinated, although it is recommended to wait if the child has evolving neurological abnormalities, current neurological deterioration, or poorly controlled epilepsy.¹ In these situations, it would be wise to seek advice from the child’s consultant.¹ Similarly, children who have had febrile seizures in the past with no neurological deterioration, or who have a family history of seizures, can be safely vaccinated.¹

3. Recognise the Complex Clinical Presentation of Pertussis

As well as encouraging vaccination, the GP has a role to play in looking out for cases of pertussis, treating them appropriately, and notifying public health authorities. Unfortunately, as with many other highly infectious illnesses, pertussis is infectious long before GPs are likely to suspect anything other than a common cold.^17,18 Between 1 and 3 weeks after exposure, the child will enter the catarrhal phase and develop a runny nose, sore throat, cough, and malaise, usually with a normal temperature or mild fever.^17,18 They will then progress into the paroxysmal phase, which can last up to 10 weeks; the length of these two phases combined has given pertussis the nickname of ‘the 100-day cough’.^17,19,20

Diagnosing pertussis is always going to be a challenge. In an average winter, GPs will see hundreds of children with cough or coryza. The key to suspecting pertussis is in the nature of the cough—it is violent, with uncontrolled coughing fits.^17,18 The name ‘whooping cough’ comes from the ‘whoop’ sound, which is made by a short expiration followed by an inspiratory gasp (this video provides a useful example of the ‘whoop’ sound associated with pertussis).^17,18,21 It is most commonly seen in children, and is less common in adults and babies aged under 3 months.¹⁸ Coughing fits occur regularly (an average of 15 in 24 hours), and can cause vomiting, cyanosis in children, and sweating or cough syncope in adults.²¹ Again, fever is either not present or very mild.²¹ After a paroxysmal phase of up to 10 weeks, there is a convalescent phase of 2–3 weeks in which the cough improves, but a paroxysmal cough may recur if another respiratory tract infection is caught.^20,21 

Information on what to look out for in suspected cases of pertussis is presented in Box 1.⁶

4. Know How to Report and Treat Suspected Pertussis

Pertussis is a notifiable disease; notification (which is a statutory duty for registered medical professionals²²) is done at the point of suspicion of the infection by contacting the local authority or UK Health Security Agency health protection team.²³ It is useful for GPs to have the notification form²⁴ uploaded to their clinical system with demographic information already filled in. This should be sent to the local public health team, contact details for which can be found online for England, Scotland, Wales, and Northern Ireland.²² Usually, the public health team will then contact the patient directly and arrange for diagnostic testing. 

The method of diagnosis varies depending on the time since last pertussis vaccination and the duration of the cough. It may include culture or polymerase chain reaction analysis of a nasopharyngeal aspirate sample or swab, serology, or oral fluid testing.⁶ The patient should stay away from work or school for 2 days after they have started antibiotics, or for 21 days after the onset of symptoms if antibiotics are not given.^18,23 

Antibiotic Prescription

Although good antibiotic stewardship is essential, if pertussis is suspected and it is within 14 days of the onset of the cough, then antibiotics are indicated.⁶ Specifically, patients should be prescribed a macrolide;¹⁹ this may or may not significantly shorten the duration of the cough,¹⁸ and it can take several weeks to resolve completely. Antibiotics do not have any benefit (in terms of reducing either symptoms or infectivity) if given more than 21 days after the onset of the cough.¹⁸

When to Treat Close Contacts 

A close contact is defined as a family member, someone living in the same household, or those in institutions such as boarding schools who sleep in the same room.⁶ Work contacts and those in the same class at school are generally not defined as close contacts.⁶ Close contacts should also be treated if the index case has had symptoms for less than 21 days and the close contact is in a priority group for public health action.⁶ These largely consist of babies, pregnant women, and those in close contact with babies; more detail is given in Box 2.^6,19

Contacts do not need to stay off work or school, but should be offered immunisation if they are not already fully immunised.¹⁹ A booster should also be offered to any contact aged 10 years or older who has not had a vaccination in the preceding 5 years and has not had a tetanus/diphtheria/polio vaccine in the preceding month.¹⁹ If in doubt, the local health protection team should be able to advise on this; strictly speaking, treatment of contacts is not contractually the responsibility of general practice, and should be undertaken by public health authorities, unless there is an enhanced service in the locality that enables this.⁶ The index case should also receive any outstanding immunisations after they have recovered from the acute illness.¹⁹

5. Refer to Secondary Care When Appropriate

In England, between 2013 and the end of April 2024, there have been 29 deaths of babies too young to be fully vaccinated—this includes eight deaths in infants between January and April 2024.² As always, anyone who appears to be severely unwell (for example, significant dyspnoea or apnoeic events) should be referred to hospital, but GPs should also refer all those aged 6 months or younger with suspected pertussis,¹⁹ and tell their parents or carers that they are likely to be admitted. This is because most complications and deaths occur in this age group, and the mortality rate for pertussis is 1% in those aged under 2 months.²⁵ 

Summary 

Whooping cough is a very unpleasant infection; it can cause a cough that persists for many weeks, and is associated with significant mortality in infants. Cases are rising, so it is a diagnosis that should be on the radar—GPs must be prepared to treat and notify at the point of suspicion, and should actively promote pertussis vaccination to pregnant women and anyone else who is not fully vaccinated.