Fri Feb 6

Whooping cough cases are at their highest level in 35 years – so why the surge?

Written by: Archana Koirala, Paediatrician and Infectious Diseases Specialist; Clinical Researcher, University of Sydney

Australia is battling its biggest rise ^[1] in whooping cough cases in 35 years.

During 2024 and 2025 Australia recorded 82,513 whooping cough cases – the highest number since monitoring began in 1991.

Also known as pertussis or the “100-day cough”, whooping cough is a potentially fatal respiratory illness which causes severe coughing episodes.

It spreads from one person to another and is particularly deadly among infants.

So why the surge? And how can you protect yourself and your loved ones?

What is whooping cough?

Whooping cough ^[2] is a respiratory infection caused by the bacteria Bordetella pertussis.

Transmission occurs through close contact with infected people such as via coughing and sneezing.

Early symptoms ^[3] include runny nose or sore throat. This is called the “catarrhal phase” and can look similar to a common cold.

A persistent cough comes next, and typically lasts between six and ten weeks.

This leads to intense bouts of coughing, with babies and children often making high-pitched “whoop” sounds ^[4] when they breath in. This is where the term “whooping cough” comes from.

Whooping cough can be very severe in newborn babies and infants. About one in 125 ^[5] babies with whooping cough aged below six months dies from pneumonia or brain damage.

Household contacts and carers often pass the illness onto infants, with parents ^[6] the source of infection in more than 50% of cases. Infants can also pick up an infection from siblings ^[7] and health-care ^[8] workers.

Complications in older children and adults include interrupted sleep and pneumonia, a lung infection which can require hospitalisation. Patients can even sustain rib fractures ^[9] from coughing so hard.

Antibiotics, when given early ^[10], can stop disease progression.

However after the cough is established, which is when most people realise they are infected, antibiotics have little effect ^[11] on the disease’s progression.

But, there’s a vaccine for it?

Yes. The whooping cough vaccine is given as a combination vaccine with diphtheria and tetanus.

In Australia, this vaccine is part of routine infant and childhood immunisation schedules. A booster dose is also given to Year 7 students.

Pregnant women are advised to vaccinate every pregnancy to boost the production and transfer of antibodies to their unborn baby. This also helps protect infants who are too young to be immunised.

A 2025 study ^[12] from Denmark found vaccination during pregnancy to be 72% effective against laboratory confirmed whooping cough.

Although infants are most vulnerable to whooping cough, it can cause infection across all ages and put a large strain on the health-care system, especially for adults aged over 50 ^[13].

To protect themselves and limit spread of the disease, adults should get vaccinated every ten years.

Australia’s national vaccine regulator checks the safety of whooping cough vaccines each year ^[14]. Ongoing monitoring over many years shows these vaccines are safe and continue to protect people of all ages.

But low immunisation rates among children and adolescents remain a concern, with new data ^[15] showing Australia’s 2024-25 childhood immunisation rate was the lowest in a decade.

Only about one-fifth of adults 50 years and older are up to date ^[16] with the whooping cough vaccine. This means they have had a booster within the last ten years.

Why are there so many cases right now?

Whooping cough is a challenging disease to control because immunity, acquired through immunisation or natural infection, wanes over time ^[17]. This gives rise to whooping cough epidemics every two to three years.

Whooping cough is most commonly diagnosed using PCR testing of a throat swab. This usually involves visiting a GP to get the swab sent to a lab, and then waiting for the results. This method has been routinely used ^[18] since the early 2000s.

In 2024, 57,257 whooping cough cases were detected ^[19] in Australia. This included a case where a child with an antibiotic-resistant infection required intensive care support ^[20].

This represents the highest notification rate since records began in 1991. And it reflects a true increase in the prevalence, as well as awareness and testing, of whooping cough.

The 2024 surge in cases ^[21] was likely due, at least in part, to COVID public health restrictions which disrupted the usual epidemic cycle.

During this time, many children didn’t get the normal immune “boost” after being vaccinated and exposed to the bacteria. This left them more vulnerable to infection, particularly when authorities lifted social distancing restrictions.

Whooping cough was also widespread in 2025 ^[22] with 25,256 cases reported that year. All age groups were affected, but notification rates were highest among school-aged and preschool-aged children.

Unfortunately, whooping cough isn’t going away anytime soon. However, timely vaccination across all ages is vital to curb its spread and protect vulnerable populations.