Do vaccines work in young babies?


Yes. Contact with the millions of germs that babies come into contact with every day, from the air, surfaces, and people around them and immunisation strengthen an infant’s immune system by teaching it to respond to germs. Vaccines on the childhood schedule have been proven both safe and effective in six week old infants.  It is important that all the scheduled doses are received, as best protection does not occur after only one dose. Some vaccines (such as the pneumococcal and Haemophilus influenzae type b vaccines) require infants to receive more doses than older children to get the same level of protection.

FAQ types: 


Common Name: 
Whooping cough
Parents & Caregivers

Pertussis, commonly known as whooping cough, is a highly infectious bacterial infection spread by coughing and sneezing. It causes severe bouts of coughing, which may be accompanied by vomiting and a whooping sound. Pertussis can last up to 3 months and is sometimes referred to as the ‘100 day cough.’ The symptoms are more obvious in children, because infants and adults are less likely to ‘whoop.’

The current New Zealand situation: 

New Zealand has epidemics every 3-5 years with several thousand cases (mostly young children) reported in each epidemic. Older adolescents and adult pertussis often goes unrecognised and is often under reported. Up to a third of adolescents and young adults with a persistent cough have evidence of recent pertussis infection.


Pertussis can be divided into three stages:

The initial stage, following the incubation stage, is called the catarrhal stage is the most infectious. It lasts 7-10 days and can include a runny nose, sneezing, slight fever, and a mild irritating cough.

The second stage or paroxysmal stage usually lasts 2-4 weeks, but can persist for up to 10 weeks. A paroxysm is a spasm of coughing followed by a big breath in or high pitched whoop in children. Infants and adults generally do not have the characteristic 'whoop' sound. Infants and young children often appear very ill, and may turn blue and vomit with coughing bouts.

The convalescent stage may last for months. Although the cough eventually disappears after several weeks, coughing fits may recur whenever the patient suffers any subsequent respiratory infection.


How do you get it?: 

Pertussis is highly contagious and is spread by coughing and sneezing. It infects around 90% of non-immune household contacts and 50 to 80% of non-immune school contacts. Many babies catch it from their older siblings or parents - often before they are old enough to be fully vaccinated.

What are the risks?: 

Around five in 10 babies who catch pertussis before the age of 12 months require hospitalisation and 1-2 in 100 of those hospitalised die from pertussis infection. Severe coughing can temporarily stop the oxygen supply to the brain (hypoxia). In around two in 1000 children pertussis leads to permanent brain damage, paralysis, deafness or blindness. Secondary infections such as pneumonia and ear infections can occur.

The disease is usually milder in adolescents and adults, consisting of a persistent cough similar to that found in other upper respiratory infections, although some adults will collapse or experience a rib fracture from violent coughing. Both hospitalisations and deaths are likely to be under-estimated in adults due to the lack of the ‘whooping’ sound.

Who is most at risk?: 

Those most at risk of serious disease are infants under 12 months of age. Infants who do not receive doses of pertussis containing vaccine at the scheduled times of 6 weeks, 3 months, and 5 months have up to a five-fold increased risk of being hospitalised with pertussis.

Preventing Disease Spread: 

A free whooping cough booster immunisation is recommended for pregnant women between 28-38 weeks gestation. The booster immunisation increases the amount of protection against whooping cough that can pass through the placenta into the baby, providing them with some of their own protection against severe whooping cough for a period of time after their birth (around 4-6 weeks). The tetanus, diphtheria and pertussis (whooping cough) booster immunisation can also reduce the risk the mother will have the disease when the baby is born and for the subsequent year when the baby's risk of complications from whooping cough is highest.

On-time immunisations for infants at 6 weeks, 3 months and 5 months in addition to children receiving boosters at four years and 11 years is the best prevention.

Breastfeeding does not provide direct protection against whooping cough.

Antibiotics do not cure pertussis but are given to reduce the spread of infection to others.

All cases of pertussis should be excluded from early childhood services, school, or community gatherings until they are well enough to attend and have either received five days of antibiotics or three weeks have elapsed since the onset of coughing spasms.


Health Professionals
Causative organism: 

Pertussis is caused by a bacterium, Bordetella pertussis; a gram-negative bacillus, which colonises the upper respiratory tract. There are other organisms such as Bordetella parapertussis, Mycoplasma pneumoniae and Chlamydia pneumoniae, which can cause a pertussis-like illness.

Clinical signs, symptoms and complications: 

Pertussis disease can be divided into three stages:

Catarrhal stage

Can last 7-10 days and includes a runny nose, sneezing, low-grade fever, and a mild cough (all similar symptoms to the common cold).

 Paroxysmal stage

  • Usually lasts 1-6 weeks, but can persist for up to 10 weeks.
  • The characteristic symptom is a burst, or paroxysm, of numerous, rapid coughs.
  • At the end of the paroxysm the patient suffers from a long inhaling effort that is characterized by a high-pitched whoop.
  • Infants and young children often appear very ill and distressed, and may turn blue and vomit. Infants generally do not have the characteristic “whoop” sound.

Convalescent stage

  • May last for months.
  • Although the cough usually disappears after 2-3 weeks, paroxysms may recur whenever the patient suffers any subsequent respiratory infection.
  • Disease is more severe in infants and young children.
  • The cough may persist for up to 3 months and is often associated with vomiting.
  • Severe coughing may lead to brain hypoxia. In 1-3 per 1000 children, whooping cough leads to permanent brain damage, paralysis, deafness or blindness.

The disease is usually milder in adolescents and adults, consisting of a persistent cough similar to that found in other upper respiratory infections. However, these individuals are still able to transmit the disease to others, including unimmunised or incompletely immunised infants.

Pertussis immunity wanes over time; both following natural disease and vaccination (immunity lasts 4–10 years). Re-infection may present as a persistent cough, rather than typical pertussis.


Method of transmission: 

Pertussis is spread through the air by infectious droplets and is highly contagious infecting 90% of susceptible household contacts and 50 to 80% of susceptible school contacts. The incubation period is commonly 7-10 days, with an upper limit of 21 days. Many babies contract pertussis from their older siblings or parents.

Public health significance: 

Pertussis kills about 250,000 children worldwide each year. Many children are left with brain damage from pertussis infection. Pertussis is highly infectious and around 90% of non-immune household contacts will contract it.

Most countries have epidemics every three to five years.

Both hospitalisation and deaths from pertussis are likely to be underestimated as infants, particularly preterm, may either present without characteristic symptoms or be misclassified as sudden infant death syndrome.

It has been estimated that up to 20% of severe adult coughs 1-3 months untreated, could be caused by pertussis infection. These individuals are a significant reservoir of infection.

Some countries such as USA, Australia and Canada are now identifying higher rates of pertussis infection, especially in adolescents and adults. The cause of this is not yet fully explained however these countries are introducing pertussis boosters for adolescents.

Those most at risk are young babies. Around 50% of those who catch pertussis before the age of 12 months require hospitalisation. Children under 12 months who are ill enough to be admitted to hospital have a 1-2 in 100 chance of dying.

Currently available vaccines prevent disease much better than they prevent infection. They will not eradicate pertussis but in countries with very high immunisation coverage rates (>95%), the three to fiuve yearly epidemics affect fewer individuals and the resultant disease is less severe than in unvaccinated communities.


New Zealand epidemiology: 

The estimated pertussis case fatality rate in New Zealand for the period 1970 to 1992 was 0.4 percent. This is comparable to reported case fatality rates from the UK and the US over a similar period. There were no deaths from pertussis in New Zealand between 1988 and 1995, one death in 1996, and since 1999 there has been one death each year up to 2004. Morbidity from pertussis in New Zealand has been described primarily using hospital discharge data. National passive surveillance data has been available since 1996, when pertussis became a notifiable disease. Comparison of notification and hospitalisation data from 1996 and 1997 demonstrates that fewer than 50 percent of hospitalised cases are notified. The three to four year periodicity of pertussis epidemics in New Zealand is similar to that seen in many other countries. The decrease in the pertussis hospitalisation rate that occurred following the introduction of mass immunisation has not been sustained.


There is almost no maternal protection passed to the newborn against pertussis via breastmilk.

Cases should be excluded from school or daycare until the infectious period is over (21 days from the onset of coughing or after 5 days of antibiotics). Some countries recommend health care workers and/or daycare workers with confirmed pertussis infection be placed on sick leave until fully recovered.

Pertussis vaccines were initially developed in the 1940s.

There are two types of pertussis vaccine commonly used internationally: whole cell pertussis vaccine (wP) and acellular vaccine (aP). Both vaccines have similar efficacy but acellular vaccines cause significantly fewer adverse reactions than whole cell vaccines. Where feasible and available, acellular vaccines should be used in preference to whole cell vaccines.

Acellular pertussis-containing vaccines have now replaced whole-cell vaccines in many countries, including New Zealand. There are a number of acellular pertussis vaccines, which contain three or more purified components of B. pertussis: pertussis toxin (PT), filamentous haemagglutinin (FHA), pertactin (PRN), and fimbrial antigens or agglutinogens.


Antibiotics have no role in treating pertussis. However they are given to reduce transmission of the organism and may be given to all household and other close contacts of the patient.

Identification of pertussis infection and prescription of antibiotics for women in the third trimester of pregnancy minimises the spread to non-immune infants in the first month of life.

Disease Effects vs Vaccine Side Effects (Table)
Disease Description: 

A highly contagious bacterial illness lasting for weeks to months that may cause uncontrollable coughing fits. Pertussis is very serious in young infants.

Effects of disease: 
Dehydration, weight loss.
Ear infection (otitis media).
Lack of oxygen (hypoxia) during coughing fits.
Bleeding in the eye (sub-conjunctival haemorrhage).
Hospitalisation (5 infants in 10 cases aged under 12 months).
Slowed or stopped breathing (apnoea).
Convulsions (seizures).
Death for 1—2 infants out of 100 hospitalised infants.
Brain inflammation (encephalitis).
Violent coughing can result in urinary incontinence, ear infection, nose bleeds, collapsing (syncope), pneumonia, or broken ribs in adults.
Common side effects of vaccine: 
Mild pain, redness and swelling around injection site.
Headache or nausea.
Decreased appetite.
Vomiting or diarrhoea.
Irritability, restlessness.
Unusual crying.
Limb swelling after the 4th or 5th vaccine dose.
Muscle or joint stiffness or pain.
Rare side effects of vaccine: 
Temporary low platelet count.
Persistent inconsolable screaming.
Hypotonic, hyporesponsive episode (HHE) in infants.
Sterile (infection free) abscess at the injection site.
Severe allergic reaction (anaphylaxis).
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