Pertussis/whooping cough vaccine

Pertussis, better known as whooping cough, is an infectious disease caused by the bacterium – Bordetella pertussis. It can cause serious illness, which can be especially severe in young babies.

There are two types of pertussis vaccine used in global vaccination programmes – the whole cell pertussis vaccine (wP) and the acellular pertussis vaccine (aP). Neither vaccine contains live bacteria, and the vaccines cannot cause the disease itself. Both vaccines protect against pertussis infection.

The wP vaccine contains the killed whole cells of the pertussis bacteria. The whole cell pertussis vaccine (wP) was used in the UK infant vaccination programme until 2004 when it was replaced by the acellular pertussis vaccine (aP).

The acellular pertussis vaccine replaced the wP vaccine in the UK as it causes less fever, and local reactions (such as swelling and pain in the leg where the vaccine was given).

The acellular pertussis vaccine (aP) contains between three and five proteins purified from the pertussis bacteria. The vaccine is not available on its own. It is given in combination vaccines to babies and young children in the UK as part of the 6-in-1 vaccine, and the 4-in-1 pre-school booster. 

Pregnant individuals are also offered a pertussis-containing vaccine from week 16 of their pregnancy, to protect their infant once they are born but too young to be vaccinated. For more information about please read the section below -  pertussis vaccination in pregnancy. 

In the UK babies are given a dose of the pertussis vaccine at 8 weeks, 12 weeks and 16 weeks of age – a total of three doses, as part of the 6-in1 vaccine. For maximum protection, this is further boosted when they reach three years and four months of age, as part of the pre-school booster.

Those who are pregnant are also offered the pertussis vaccine. In the UK, this usually coincides with their 20-week scan, although it can be given from week 16 of pregnancy, up until week 32. This is because of the risk whooping cough poses to newborn babies, who are not vaccinated until they are eight weeks old in the UK, and are not fully protected until after their third dose of vaccine at four months of age.

The acellular pertussis vaccines (aP) all contain proteins from the pertussis bacteria, rather than the whole cell. Apart from the active ingredients (the antigens), which produce the immune response, these pertussis-containing vaccines also include very small amounts of other ingredients. None of them contain porcine gelatine. 

Boostrix-IPV (used in the UK for the pre-school booster and in pregnancy if Adacel is not available)

In addition to the active ingredients that produce the immune response to diphtheria, pertussis/whooping cough, polio and tetanus, and water, Boosterix-IPV contains:

• aluminum, which increases the immune response to the vaccine
• Medium 199, a stabiliser containing amino acids, mineral salts, vitamins and other substances
• sodium chloride (salt)
• polysorbate, used as an emulsifier (to hold other ingredients together)

The polio part of the vaccine is grown in the laboratory using cultured animal cells.

Adacel

As well as the active ingredients, Adacel contains:

• aluminium phosphate, which is used to increase the immune response to the vaccine
• phenoxyethanol. This is used as a preservative. It is also found in a range of cosmetics and other products.
• water

Other brands of pertussis-containing vaccine offered to pregnant women in other countries may contain different ingredients. If you are not in the UK, ask for the patient information leaflet for the vaccine you are offered.

Infanrix hexa and Vaxelis (used in the UK for the 6-in-1)   

Apart from the active ingredients (antigens) that produce the immune response to diphtheria, tetanus, pertussis/whooping cough, polio, Hib and hepatitis B, these vaccines contain water and very small amounts of other added ingredients. Many of these are already found naturally in the body or food.  

Added ingredients include, but are not limited to:

• aluminium, which strengthens and lengthens the immune response to the vaccine
• lactose and Medium 199 (containing amino acids, mineral salts and vitamins), both used as stabilisers
• sodium chloride (table salt) and sodium phosphate (found naturally in some foods) 

The final vaccine may also contain traces of these products that are used during the manufacturing process:

• formaldehyde, an organic compound used to inactivate (kill) the viruses used in the vaccine
• yeast proteins from the yeast used to grow the hepatitis B proteins for the vaccine. A tiny quantity may remain in the vaccine, but there is no evidence that this can cause allergic reactions.
• antibiotics (neomycin, polymyxin and streptomycin), used to stop bacteria growing and contaminating the vaccine during manufacture. People who know they are allergic to these particular antibiotics, should seek specialist advice. Antibiotics which most commonly cause allergic reactions are not used.

Some of the active ingredients for these vaccines are grown in a laboratory. This includes:

• the polio part of the vaccine is grown in the laboratory using animal cell strains
• the hepatitis B proteins for the vaccine are grown in yeast cells. This process is called recombinant DNA technology.

Other brands of the 6-in-1 vaccine used in non-UK countries may contain different ingredients. If you want to find out more about the specific ingredients of the vaccine you are offered, ask for the specific patient information leaflet.

You can also read more about vaccine ingredients here.

Babies under the age of three months are at greatest risk of complications and death from pertussis, yet they are not fully protected until they have had the three doses of vaccine between the age of 8 weeks and 16 weeks.  

Vaccinating mothers during pregnancy can help protect these newborn babies. Pregnant people can be vaccinated any time after week 16 of their pregnancy up until 32 weeks. In the UK, those who are pregnant will usually be told about the vaccine at their 20 week scan.

How does vaccinating during pregnancy help protect new born babies?

Vaccination during weeks 16 to 32 of pregnancy helps the mother to make antibodies that can fight pertussis. It takes about two weeks for antibody levels to peak. These antibodies are then transferred through the placenta to the baby, who then has the mother’s own protection against the disease in their blood right from birth. Very small quantities of pertussis antibodies may also be transferred to the baby through breast milk.

As well as protecting their newborn baby, the vaccine also protects the pregnant individual themselves against pertussis, and therefore reduces the chance of the infection being passed from themselves to their newborn baby.

Although those who are pregnant can be vaccinated any time up until labour, it is advised they are vaccinated before week 32 because it takes about two weeks for the immune system to make antibodies and pass these across to the unborn baby.

The protection offered by the mother’s antibodies lasts only a few months. It is therefore important for babies to get their routine immunisations (see the 6-in-1 vaccine) when they are two, three and four months old, so they continue to be protected.

It is recommended that people have the pertussis vaccine in each of their pregnancies, even if they have been previously vaccinated.

Why not vaccinate babies against pertussis at birth?

There are two reasons why vaccinating babies at birth does not offer them the best protection against pertussis.

First, newborn babies’ immune systems may have a lower response to a dose of pertussis vaccine given early in life. Second, vaccination does not offer immediate protection. It takes several days for a baby’s immune system to respond to the vaccine, and at least two doses of vaccine are needed to give significant levels of protection.

What vaccine is given during pregnancy?

The pertussis vaccine is only available in combination with other vaccines. From July 2024 the vaccine used in the UK changed to Adacel, a vaccine that contains pertussis, along with tetanus and diphtheria. Previously Boosterix-IPV (also used as the pre-school booster) was given during pregnancy. This also protects against polio, as well as pertussis, tetanus and diphtheria.

Adacel has been introduced for maternal pertussis vaccination as an alternative to Boosterix-IPV, as there is some evidence that the polio component in the maternal Boosterix vaccine might reduce the antibody responses to the later infant doses of the polio vaccine.

The change is being made to optimise immune responses, although it is unknown whether this affects susceptibility to polio.

While the switch from Boosterix-IPV to Adacel is taking place, pregnant women may still be offered Boosterix-IPV, as it is safe, suitable and effective.  

Neither Adacel or Boosterix-IPV contain any live bacteria or viruses, and cannot cause any of the diseases they protect against. One dose of either vaccine is given during pregnancy.

It’s worth noting that both Adacel and Boostrix-IPV can be given safely at the same time as the flu vaccine, if the recommended timings coincide.

For more information, about Adacel or Boosterix-IPV, please read the patient information leaflets.

Adacel patient information leaflet.

Boostrix-IPV patient information leaflet.

Is the pertussis vaccine safe in pregnancy?

If you are pregnant, it is understandable to be worried about any potential effects of a vaccine on an unborn child. There is good evidence that the recommended pertussis vaccines can be given safely in pregnancy without causing harm to mother or to baby.

They have been thoroughly assessed in large clinical studies of pregnant women to ensure they are safe. For example, a systematic review that included 21 studies, and published in the journal Obstetrics and Gynecology in 2017, concluded that Tdap vaccines delivered during the second and third trimesters of pregnancy are not associated with “clinically significant harms” to either the unborn fetus or newly born baby.

And a large Australian study of nearly 82,000 babies looked at rates of autism in babies born to women who had been vaccinated against whooping cough in pregnancy with the Tdap vaccine which, like Adacel, projects against diphtheria and tetanus as well as whooping cough, but not polio. The study found that these babies were no more likely to have autism than those born to women who had not been vaccinated against whooping cough in pregnancy.

Adacel has been licensed for use in the UK since 2016 and millions of doses have been given as part of maternal pertussis programmes in other countries, including the USA, Australia and other European countries.

These combination vaccines are being used because a single pertussis vaccine is not available. Boostrix-IPV and Adacel both contain low-dose diphtheria and tetanus, which means that the rate of side effects is lower than with the 6-in-1 vaccine, for example.

A large safety study  involving over 20,000 vaccinated pregnant women, undertaken by the UK's Medicines and Healthcare products Regulatory Agency (MHRA), has found no risks in pregnancy from Repevax, which was the vaccine used for this programme until summer 2014. Repevax is very similar to Boostrix-IPV but made by a different manufacturer.

Pregnant people in the UK have been recommended the pertussis vaccine since 2012, when there was an outbreak of whooping cough in the country. During that year, there were over 9,300 cases in England alone. This was more than ten times the number of cases seen over the previous 10 years. The causes of the epidemic are not clear.

The years since 2012 saw a fall in cases, although numbers are still higher when compared to the years before the 2012 epidemic.  The lockdowns and social distancing measures put in place during the COVID-19 pandemic resulted in a large drop in cases.

But since the final months of 2023 the UK has again been experiencing an increase. In England, between January and May 2024, there were 7,599 confirmed cases reported to the UK Health Security Agency, with eight infant deaths over the same time. In all, there have been ten infant deaths since this outbreak began.  By contrast, there were just 858 cases reported during the whole of 2023.

Laboratory confirmed cases of pertussis by month in England: 2018 - May 2024

Source: UK Health Security Agency

The current outbreak comes against the backdrop of a steady decline in the number of pregnant women getting vaccinated against pertussis. In 2023 vaccine coverage stood at around 60% for England, with large regional variations. London dropped from 56.7% in June 2019 to 37.2% in June 2023. This puts the gains made by the maternal pertussis vaccination programme at risk.

A similar programme of pertussis vaccination in pregnancy is also offered in the US, Australia, and some other European countries.

Please go to our Vaccination and pregnancy pages if you want to find out more about the safety of vaccines during pregnancy.