THE acellular pertussis vaccine is less effective in preventing disease in the longer term than its whole-cell predecessor but, with greater tolerability, it remains the best current option, say two experts in paediatric infectious diseases.

They were commenting on research undertaken in Queensland, that found pertussis was three times more likely to be reported among children who had had a primary course of acellular pertussis vaccine (diphtheria–tetanus–acellular pertussis or DTPa) than in those who had had a primary course of whole-cell vaccine (DTPw). The study was published in a research letter to the Journal of the American Medical Association. (1)

Professor Peter McIntyre, director of the National Centre for Immunisation Research and Surveillance, said bringing back the whole-cell pertussis vaccine was not the answer because the high frequency of side effects resulted in low pertussis vaccine coverage. He said this was associated with more hospitalisations and deaths during pertussis epidemics in the 1990s.

He said in the whole-cell era, many children had only one or none of the recommended three doses of vaccine because parents, often encouraged by their doctors, refused more doses after their child experienced side effects.

Professor McIntyre said the recent Queensland analysis suggested that we may have traded the problem of low coverage with the whole-cell vaccine (which led to more severe pertussis cases in infants) for the lesser, but still important, problem of more rapid waning of immunity after the acellular vaccine.

“We now have almost 95% of children receiving three doses of the acellular vaccine by two years of age, which is working well in preventing severe disease in the short term, but we are seeing more, less severe, pertussis cases in older children due to more testing and more rapid waning of immunity than occurred among children who got their three doses of whole-cell vaccine.”

Study co-author Associate Professor Stephen Lambert, senior research fellow with the Queensland Children’s Medical Research Institute, said it was important to remember that the whole-cell vaccine was “pretty unpleasant”.

“Up to about 50% of children would have an unpleasant injection site reaction, which could include redness, swelling and pain”, he said.

Less common reactions included fevers up to 40 degrees, febrile convulsion, inconsolable crying and hypotonic–hyporesponsive episodes.

Professor Lambert agreed that the acellular vaccine was effective in preventing severe disease. “Children who are immunised tend to have milder illness and transmit less frequently”, he said. “Even from the first one or two doses, the risk of an infant being hospitalised or ending up in intensive care drops very dramatically.”

The current epidemic was not related to the effectiveness of the vaccine, Professor Lambert said. “This is just one piece of a larger, more complex puzzle. It certainly doesn’t explain why we’re experiencing a nationwide pertussis epidemic.”

He said one factor that may partly explain the higher rate of pertussis was improved detection of the disease with the expansion of PCR testing.

Professor Lambert said vaccine manufacturers were looking into modifying their acellular products by adding new adjuvants. A new live-attenuated vaccine was in the pipeline, but this was still many years away, he said.

Professor McIntyre said investigations were underway in Australia into the vaccination of newborns and the immunisation of pregnant women to evaluate whether this protected newborn babies earlier.

“On top of these options to use the existing vaccines better, there’s no doubt that we do need better vaccines against pertussis, but the message that the acellular vaccine is still working well to protect against severe disease in young infants who receive it is an important one in terms of maintaining confidence”, he said.

– Nicole Mackee


1. JAMA 2012; 308: 454-456

Posted 13 August 2012

8 thoughts on “Acellular pertussis shot still the best option

  1. Anonymous says:

    the photo of a baby receiving an injection into the right lateral thigh seems to be showing very poor technique with an unrestrained limb and the possibility of a kick causing a much deeper injection than intended. Am I being overly critical?

  2. says:

    I agree, it doesn’t appear ideal. Unfortunately it was the best of some very odd injection techniques in our photo library. They could do with a medical advisor. Ruth Armstrong, Medical Editor, InSight

  3. Trilochan Mukkur says:

    I agree with with Professors McIntyre and Lambert that the currently marketed pertussis vaccine is still the best option available today for prevention of whooping cough. However, it is also important that the NHMRC support the development of novel whooping cough vaccines which can induce the desired immune response with potential to induce long term protection. My research group and Dr Locht’s research group at the Pasteur Institute have developed live attenuated vaccines which are different from each other in the sense that in our vaccine candidate, an essential gene has been deleted such that it cannot revert back to virulence or pathogenicity. It has taken us 10 years to develop this vaccine and despite several attempts, no NHMRC support has been approved for the last several years for continuation and completion of this work despite Australia’s leadership in this field. On the other hand, the Pasteur Istitute has funded Dr Locht’s project quite extensively [as I understand it]. Those interested to familiarise themselves with our discovery, are welcome to refer to our recent published work [Journal of Microbiology & Biotechnology, 2012 22(6):856-65] on the development of live attenuated vaccine.

  4. Kalori says:

    This gets confusing! The acellular vaccine has been shown to cause a 40-fold increase in parapertussis in the lungs of mice as long ago as 2010. And more recent data from UNSW researchers suggest the acellular pertussis vaccine “could be contributing to the emergence of new and potentially more dangerous clones.”
    The whole-cell vaccine is not a pleasant alternative as Prof Lambert points out. The last thing the mother of a 2 month-old child wants is a baby who won’t stop crying or just has a painful, red, swollen arm.
    Maintaining confidence is a not an issue if the vaccine is safe. That is where we need to start! It is not too much to ask for a vaccine that does not foster more dangerous forms of pertussis, and also does not cause injection site reactions in 50% of children. Is it?

  5. Trilochan Mukkur says:

    I agree with Dr Kalori’s comments. It is to ensure minimisation of side reactions at the injection site that our vaccine is to be delivered by the intranasal route. The funds that we have been attempting to get from the NHMRC is to make our attenuated vaccine strain the safest vaccine ever by further genetic manipulations such that immunisation with this live attenuated vaccine will also neutralise toxins. Our preliminary data indicate a level of protection offered against parapertussis as well but we are eagerly awaiting the execution of our final experiments.

  6. drking33 says:

    FACT: 25 years ago, the protection provided by the whole-cell pertussis vaccines (DTwcP) was found to wane after 3 years (Pediatric Infect Dis J 1987 Feb; 6(2): 141-144) similar to the loss in protection alluded to for today’s acellular (DTaP) vaccines (Clin Infect Dis. 2012; 54(12): 1730-1735).

    If readers want to know about the current “whooping cough” outbreaks in the US (and elsewhere, including Australia) and how such were predicted 25 years ago, you should read my in-depth, science-based review article posted at:
    to understand that, at best, the pertussis components in the DTaP/Tdap vaccines:
    a) are NOT effective in preventing “whooping cough” because they are ineffective against “whooping cough” cases caused by B. parapertussis (Clin Infect Dis. 2012; 54(4): 534-537 where B. parapertussis was the reported causative organism in 13.99% of “whooping cough” cases);
    b) simply postpone the risk for contracting a Bordetella-pertussis-caused case of whooping cough by about 3-5 years (for SOME (~ 70%) of those vaccinated – see references in first paragraph);
    c) create silent disease carriers, “Pertussis Harrys” (J Clin Microbiol, 1977 Aug; 6(2): 154-160), that spread disease though they have no symptoms; and
    d) increase the risk that those who are too young to be vaccinated will come down with “whooping cough” (Pediatric Infect Dis J 1994; 13(5): 343-344).

    Hopefully, this will spread this message throughout those areas of Australia that have a high incidence rate so that all will know that the “pertussis” vaccines are ineffective vaccines that actually help spread “whooping cough”, have increased the virulence of Bordetella pertussis strains (BMC Genomics 2010, 11:627 doi:10.1186/1471-2164-11-627 and Emerg Infect Dis. 2009 August; 15(8): 1206–1213), and have helped increase the percentage of “whooping cough” cases that are caused by Bordetella parapertussis, a related organism for which the “pertussis” vaccines provide no protection as well as cases caused by other less-common organisms (e.g., Bordetella holmesii (, Mycoplasma pneumoniae, and Chlamydophila pneumoniae (Pathogens in lower respiratory tract infections – In: Molecular diagnostics of infectious diseases / Kessler, Harald H. [edit.].- Berlin: De Gruyter, 2010. Pages 115-134.

  7. Sue Ieraci says:

    Dr Paul King, PhD, (whose comment is above) is an “analytical chemist” who campaigns against vaccine preservatives and effectivness. He is neither a clinician nor a vaccine researcher. It is not possible for vaccines to “increase the virulence” of pertussis strains – vaccines have no effect on mutations in organisms. Dr King asserts on his website that ” what needs to be done to change the vaccination paradigm from today’s increasingly restricted “opt out” reality to a science-based “opt in” medical choice.” I would advise readers to take his comments with a grain of salt.

  8. Sue Ieraci says:

    Here is another extract from Dr Paul King’s website, which puts his comments above in more context:
    “….for children under 1 year of age, now that Thimerosal has been reduced in or removed from these vaccines, the “pertussis toxins”, including the endotoxins that the pertussis components introduce, in the aluminum-adjuvanted, diphtheria, tetanus and per-tussis (DTP) vaccines is probably responsible for the majority of the harm and deaths in this age group even though the Establishment uses terms like SIDS (sudden infant death syndrome), SBS (shaken baby syndrome) and SUID (sudden unexplained infant death) to avoid having to use the more appropriate acronym, DBV (death by vaccine), for many of the deaths in babies under 1 year of age that occur shortly after a DTP shot (typically within 21 days).” Again, I suggest caution in accepting his assertions.

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