Increasing pertussis (whooping cough) cases in Victoria

What is the issue?

Cases of pertussis (whooping cough) are continuing to increase in Victoria. There have been over 10 times the number of pertussis cases in 2024 than for the whole of 2023. Children aged 9-12 years account for nearly 40% of all notified cases.

All Australian states and territories have recorded increases in pertussis cases in 2024 compared to previous years. Population-wide increases in pertussis typically occur every few years. The increasing number of pertussis infections seen in Victoria is a public health concern, as it has led to an increase in cases amongst the most vulnerable population – infants under the age of 6 months.

Who is at risk?

Anyone can get pertussis. Infants less than 6 months of age are at greatest risk of severe disease, hospitalisation, and death. These infants are too young to be fully immunised. Many infants who get pertussis catch it from older children and adults who might not even know they are infected.

Symptoms and transmission

Pertussis usually begins with cold-like symptoms, such as a dry cough, tiredness, runny nose, and low-grade fever, which may last for 1-2 weeks. A more definitive cough may then develop, lasting for 10 weeks or more. The cough comes in long spells and may be followed by a high-pitched ‘whooping’ sound on inhalation, or post-tussive (after coughing) vomiting in toddlers and older children.

Infants under 6 months may have apnoea (pauses in breathing), cyanosis (turning blue), feeding difficulties, gasping, or choking instead of a cough. In adolescents and adults, pertussis may present as a non-specific protracted cough.

Vaccinated people can still contract pertussis, but their symptoms are likely to be less severe, and they are less likely to transmit the infection to others.

Pertussis is mostly spread to other people by droplets from coughing or sneezing. People with pertussis are considered infectious from the onset of catarrhal (cold-like) symptoms until 21 days after the onset of cough, or until they have received 5 days of appropriate antibiotic treatment.

Immunisation

Immunisation is the best way to reduce the risk of pertussis.

Free pertussis-containing vaccine is available for the following people under the National Immunisation Program:

• Pregnant women should be vaccinated for pertussis during each pregnancy, preferably between 20 and 32 weeks gestation. Vaccination during pregnancy reduces the risk of pertussis in young infants by 90 per cent.
• Routine pertussis vaccination is recommended for infants, children, and adolescents. Vaccinate infants on time, starting at 6 weeks of age, to protect them against severe pertussis disease as soon as possible.
• Catch-up vaccines are free for eligible people aged up to 20 years, refugees and humanitarian entrants of any age, and vulnerable citizens.

Pertussis-containing vaccine is also recommended for:

• Household contacts and carers of infants less than 6 months old if they have not had one in the last 10 years.
• Childcare workers and early childhood educators working with children less than 4 years old, as well as healthcare workers are also recommended pertussis boosters every 10 years.

Recommendations

Health professionals

• Ensure infants and pregnant women are up to date with pertussis immunisations.
• It is safe to give pertussis-containing vaccine to children, adolescents or adults who have had laboratory-confirmed pertussis infection. These people should receive all routinely scheduled pertussis-containing vaccines because natural immunity does not provide lifelong protection.
• Consider pertussis in all people (including infants, children, and adults) who present with compatible symptoms.
• Remember that adults and infants sometimes do not present with classical symptoms. Therefore, it is important to retain a high clinical suspicion for pertussis.
• A nasopharyngeal aspirate/swab for PCR is the preferred diagnostic test for pertussis in all ages.
• Follow guidance on antibiotic treatment in the latest editions of the Therapeutic Guidelines: Antibiotic and the Royal Children’s Hospital Melbourne Clinical Practice Guidelines. Prophylactic antibiotics should also be recommended for certain high-risk contacts of pertussis cases.
• Azithromycin and clarithromycin oral liquids are currently in short supply.
  • Check with your local pharmacy regarding availability.
  • Prescribe tablets for doses equivalent to half or whole tablets. Tablets can be crushed for administration.
  • Two alternative azithromycin oral suspensions have been approved under Section 19A of the Therapeutic Goods Act 1989. Check the Therapeutic Goods Administration (TGA) website Section 19A approvals database for alternative products approved for supply during this shortage.
• Pertussis must be notified by medical practitioners and pathology services to the Department of Health in writing within 5 days of diagnosis.
• School and children’s services centres exclusions apply to cases and contacts. Visit the school exclusion table page for more information.

General public

• Whooping cough needs to be diagnosed and treated immediately. Seek medical attention if you or your child has any of these symptoms:
  • a severe cough which that may occur in bouts. Your child may appear well between episodes of coughing.
  • characteristic 'whooping' sound when they breath in.
  • vomiting at the end of a bout of coughing.
  • your child stops breathing for periods of time and may go blue.
• Your doctor might diagnose whooping cough by checking symptoms, doing a swab of the nose and throat, or by taking a blood test.
• Your doctor may prescribe antibiotics, which can help reduce the seriousness of symptoms and the ability to spread the infection to others.
• Keep your child home from childcare or primary school for 21 days after the onset of cough, or until they have received 5 days of appropriate antibiotic treatment. To prevent the spread of whooping cough, ensure you and your family are up to date with immunisations and follow good hygiene practices.
• If you or your family have a cough or respiratory symptoms, take particular care to stay away from babies.
• If you are unsure if you or your child are due for pertussis vaccination, discuss this with an immunisation provider, such as your doctor (GP).