Issue 11 / 29 March 2016

AS a mother and a medical journalist, I’ve long been aware of the dangers of whooping cough. I’ve read countless studies and seen heartbreaking images of coughing infants in media reports and on my Facebook feed.

However, I’ve comforted myself that almost all members of my extended family and my young daughter have been vaccinated. Pertussis can’t affect us, I thought. I was wrong.

Last month, three of my nieces and nephews and my brother-in-law all came down with whooping cough. The children were all vaccinated; the 4-year-old just in December. The complicating factor was they also have a younger sister who is only a few months old.

Although she had just had her first 6-week vaccine, she was being directly exposed to a disease that has the highest rate of disease and death in her age group.

How could a family that had done its best to protect its most vulnerable come down with such an ailment? There are media reports of whooping cough epidemics all the time.
Is the current vaccination schedule working in helping to reduce these outbreaks?

Whooping cough has long been a public health issue, however the reason for the increased levels of outbreaks in the past 20 years is due to a change in vaccination strategy.

Professor and Head of Modelling and Simulation at Murdoch Childrens Research Institute, Associate Professor Jodie McVernon says the previous “whole cell” vaccines were discontinued in the 1990s in Australia due to a high rate of fevers and other side effects. However, there have been other issues with the newer “acellular” vaccines.

“There is a growing body of evidence that the newer, acellular vaccines that we use now (which have fewer side effects) don’t protect quite as well, or for as long, making booster doses more important than ever,” Professor McVernon told MJA InSight.

Unlike some vaccines, the whooping cough vaccine isn’t one of our best vaccines, experts say. According to Professor Robert Booy, the Head of Clinical Research, National Centre for Immunisation Research and Surveillance at the University of Sydney, the whooping cough vaccine is only 60-70% effective.

“We have to be honest and say sometimes the vaccine doesn’t work,” he told MJA InSight. “It works better in the short term rather than the long term.”

Until recently, the National Immunisation Program recommended jabs at 2, 4 and 6 months with booster doses given at 4 years and 10 to 15 years. However, studies have shown children who haven’t received an 18-month booster dose have seen the effectiveness of their previous vaccinations decline progressively from 2 years of age. By 4 years old, the effectiveness of the vaccine is at less than 50%.

It is this waning immunity and an increase of infections among 2-9 year olds that has led to a change in the National Immunisation Program this year. From March 2016, children will also receive a pertussis vaccination at 18 months.

The main public health concern with whooping cough is protecting young infants, which is partly why the 18-month jab was reintroduced.

However, according to Professor McVernon, the biggest change to the current recommendations is not childhood jabs, but a recommendation for all women to receive a booster in each pregnancy.

“The recently announced maternal vaccine dose, given during the third trimester, is a major shift in vaccine strategy,” she said.

According to Dr Helen Quinn, Senior Research Fellow at the National Centre for Immunisation Research and Surveillance, this new recommendation is one of the best ways to protect young babies.

“Knowing the limitations with our current vaccine, I think we can make smarter choices with the schedule we’ve got and the recommendation of a vaccine in pregnancy is one of those choices,” she told MJA InSight.

In Australia, the maternal pertussis vaccination has only been recommended for a short time, however in the UK, it was introduced in October 2012, resulting in a fall of pertussis infections across all age groups during the time of the study. A study published in The Lancet estimated vaccine effectiveness at 91%, which the authors concluded was due to protection of infants from both passive antibodies and reduced maternal exposure.

A recent Melbourne study published in the American Journal of Obstetrics and Gynaecology suggests 28 weeks of gestation may be the optimal time for this vaccine and another study published in Clinical Infectious Diseases suggests even earlier in the second trimester “would widen the immunisation opportunity window and could improve seroprotection”.

Dr Quinn said at this stage they won’t be changing the recommended timeframe of early in the third trimester.

“We like the 28-week time point as there are other antenatal tests that get done around that time,” she said.

However, she said they acknowledge that it can be done earlier in the second trimester and if pregnant women miss the 28-week mark, they should still get vaccinated later in their pregnancy.

Other ways to protect a newborn infant include limiting exposure and by cocooning – where the father, grandparents and other adults in close contact with the new baby also get vaccinated. The current advice for health care workers and family members who come into contact with infants is to receive a diphtheria, tetanus and acellular pertussis-containing booster every 10 years, although there are no health issues if they have a reason to be vaccinated more often.

Although there are newer vaccines in development, there’s nothing likely in the short term.

According to Professor McVernon: “It’s uncertain whether these will become available for widespread use in the coming years, particularly given the success of the new maternal vaccination strategy.”

Dr Quinn says the focus now is getting the maternal vaccination nationally funded.

“Although it’s funded by the states, there is uncertainty about how long they’re planning to fund it,” she said. “Once it gets onto the national program, long-term funding is more assured.”

In my family’s instance, we were lucky as my niece didn’t contract whooping cough. Her mother was vaccinated during pregnancy, and she received a prophylactic antibiotic dose to help boost her protection.

However, many families have not been that lucky, which is why the new maternal vaccine is considered so important for future protection.

Professor Booy is unequivocal: “I need to emphasise, the most dramatic and effective way to protect babies under 6 weeks is to get pregnant mums vaccinated between 28-32 weeks of pregnancy. If you give it to the mother, it protects the mother and gives the baby more than 90% protection.”

Caitlin Wright is a medical journalist and online editor of doctorportal.com.au

9 thoughts on “Best protection from pertussis? Jab the mum

  1. Ronald Batagol says:

     

    On enquiry via my local Federal Member in late 2015, regarding the 18-month pertussis booster vaccoine, I was  advised by the Health Minister that the 18-month pertussis vaccine booster “will be added to the National Immunisation Program (NIP) schedule and available to all children at 18 months of age from early 2016, subject to vaccine supply”.

    On checking the respective websites recently, it seems that this additional booster has now been incorporated into the vaccination protocols for all the States and Territories. However, I was also advised at the time that “the implementation of new vaccines under the NIP is a major task that takes approximately 12-18 months following the Government’s decision to fund a vaccine (a number of issues including preparatory activities, communication, negotiation with States and Territories on implentation timing and requirements, were noted as matters  to be dealt with in that timeframe).  So, in summary, it seems that most importantly, State and Terrritory vaccination programs are now including the additional pertussis for 18-month booster, and that, fairly soon,  it will be an integral part of the Federal Government -funded NIP program. 

    Ron Batagol,

    Pharmacist and Obstetric Drug Information Pharmacist, Nunawading Vic 3131

  2. Randal Pittelli says:

    The problem w/ pertussis resistance to the acellular vaccine has been known by clued in clinicians for the better part of a decade. However, activists and politicians, and even much of our fraternity, have been blaming high pertussis rates on “low” vaccination rates. When desperate for budget savings, Minister Roxon unashamedly announced her government’s cuts to family benefits for those not vaccinating by referring to vaccinates rates and rising pertussis levels, but without a peep about the germ’s growing resistance to the vaccine. Neither was there a peep of correction from medical groups.

    A pertussis resistance of 30-40% is far more dangerous to the unvaccinated infant than are unvaccination rates generally less than 10%. Medicos in particular need to stop arguing that vaccination levels for pertussis are the problem — it misinforms the public, it is dishonest and thus risks harming the patient-doctor relationship, it feeds conspiracy theories of anti-vaccination parents, and it has skewed public discussion away from potential solutions (e.g., the inevitable changing of the vaccine) while public policy towards an increasingly disingenuous, creeping paternalism.

  3. University of Newcastle says:

    The above comment is incorrect. It is not a problem of pertussis resistance, but a problem of using a vaccine with relatively low effectiveness. No vaccine is 100% effective, and misinformed anti vaccination campaigners will seize on any vaccine failure as support for their conspiracy theories. The public health message that a vaccine of 60-70% effectiveness is still worth using is more complex than for a vaccine with very high effectiveness. 

    Back in the 1990s the decision to switch from whole cell to acellular pertussis vaccines was, I believe,  driven by the desire to avoid the sore leg and fever that parents had put up with for decades, thus enhancing the patient experience and acceptance of the whole immunisation program. The vaccine price was many times higher but thought to be worth it.  Studies at the time showed adequate serology and this was wrongly interpreted as equivalent immunity although it was the best evidence available at the time.

    Does anybody want to go back to the whole cell vaccine? We now have the choice of increasing the number of doses of the current vaccine across the lifespan, or trying to find something more effective. This situation needs a strong national immunisation program based on science, not a return to everyone doing their own thing.

    Dr Ben Ewald, GP Newcastle.

     

  4. Randal Pittelli says:

    I’m intrigued by your confidence that resistance isn’t an issue here. At the very least, you make it sound like there hasn’t been an *increase* in strains that the vaccine is ineffective against (thus reducing effectiveness, from an earlier high it shared with cellular vaccine of about 95% after 3 doses [98% after 4]).

    Or, if you are claiming that the evolutionary forces that cause germ selection towards strains not targeted by a vaccine do not constitute a “resistance”, I would say that your understanding of the mechanisms behind resistance is overly restrictive.

    The fact remains that the low stated effectiveness is not simply a reflection of a less-than-ideal (original or intended) coverage — coverage has been decreasing. Whether or not the reported adaptation of pertussis towards strains that the vaccine doesn’t cover is a direct result of selection pressure created by the vaccine itself, it should be pretty clear that resistance is increasing in much of the world.

    It is also true that the vaccine’s efficacy wanes, and rather quickly (while not much with the cellular vaccine), but such waning is not part of the simple stat of effectiveness as stated above and thus cannot be an excuse for its decline.

    It’s straightforward to trace the evolving debate on the resistance, with some of the first studies proposing it coming out of Australia. Many of us doctors are also researchers, after all. I would recommend starting with this 2014 Emerg Infect Diseases paper & references:
    http://www.ncbi.nlm.nih.gov/pubmed/24655754?dopt=Abstract
    It outlines several ways that the vaccine could be made more effective. One of those is inevitable.



    Dr Randal Pittelli, Clifton Beach

  5. Randal Pittelli says:

    *Correction:

    The paper I was recommending is the following:

    http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3966384/

    This 2014 J. Infect Diseases paper outlines ways that the vaccine could be made more effective:

    http://jid.oxfordjournals.org/content/209/suppl_1/S24.full

  6. Elizabeth Hart says:

    In this article Jodie McVernon says “There is a growing body of evidence that the newer, acellular vaccines that we use now (which have fewer side effects) don’t protect quite as well, or for as long, making booster doses more important than ever,”

    This situation is beyond ridiculous, with pertussis vaccination now being ‘recommended’ for children at 2, 4 and 6 months, then so-called ‘boosters’ at 18 months, again at 4 years, again between 10-15 years, and then adults are also being urged to be repeatedly revaccinated with diphtheria, tetanus and acellular pertussis vaccines, i.e. pregnant women, household contacts of infants, and healthcare workers, in other words lifelong revaccination with diphtheria, tetanus and pertussis vaccine products is being promoted.

    The clique of often industry-associated academics who have hijacked vaccination policy should be very well aware that the apparently defective acellular pertussis vaccine may actually be causing new strains of the disease to develop[1], and spreading the disease via vaccinated individuals.[2] 

    So what is the point of pushing so-called ‘boosters’ with the current pertussis vaccine?

    Certainly repeated revaccinations/’boosters’ must be a very lucrative profit centre for vaccine manufacturers, largely courtesy of the taxpayer.

    I suggest individuals are being grossly over-vaccinated with the diphtheria, tetanus and acellular pertussis vaccine products, and citizens are not being properly informed about the uncertainties surrounding this vaccination.

  7. Elizabeth Hart says:

    Ref. 1 for my previous comment:

    [1] See for example: Sharp rise in cases of new strain of whooping cough. UNSW Australia Newsroom, 21 March 2012; and Octavia, S. et al. Newly Emerging Clones of Bordetella pertussis Carrying prn2 and ptxP3 Alleles Implicated in Australian Pertussis Epidemic in 2008-2010. JID 2012:205 (15 April). Brief Report; and Stacey W Martin et al. Pertactin-Negative Bordetella pertussis Strains: Evidence for a Possible Selective Advantage. Clin Infect Dis. (2015) 60 (2): 223-227. First published online: October 9, 2014; and Safarchi A et al. Pertactin negative Bordetella pertussis demonstrates higher fitness under vaccine selection pressure in a mixed infection model. Vaccine. 2015 Oct 2. pii: S0264-410X(15)01340-7 (Epub ahead of print); and Anna M Acosta et al. Tdap Vaccine Effectiveness in Adolescents During the 2012 Washington State Pertussis Epidemic. Pediatrics April 2015; and Bart MJ et al. Global population structure and evolution of Bordetella pertussis and their relationship with vaccination. MBio. 2014 Apr 22;5(2); and Octavia S et al. Insight into evolution of Bordetella pertussis from comparative genomic analysis: evidence of vaccine-driven selection. Mol Biol Evol. 2011 Jan;28(1):707-15. Epub 2010 Sep 10; and Lam C et al. Selection of emergence of pertussis toxin promoter ptxP3 allele in the evolution of Bordetella pertussis. Infect Genet Evol. 2012 Mar;12(2):492-5. Epub 2012 Jan 24.

  8. Elizabeth Hart says:

    Ref. 2 for my previous comment:

    [2] FDA study helps provide an understanding of rising rates of whooping cough and response to vaccination. FDA News Release, 27 November 2013; and Jason M Warfel et al. Acellular pertussis vaccines protect against disease but fail to prevent infection and transmission in a nonhuman primate model. PNAS, 22 October 2013
     

  9. Lucinda White says:

    Re: Ben Ewald Back in the 1990s the decision to switch from whole cell to acellular pertussis vaccines was, I believe,  driven by the desire to avoid the sore leg and fever that parents had put up with for decades, thus enhancing the patient experience and acceptance of the whole immunisation program.

    Maybe not?

    https://www.youtube.com/watch?v=VtOh6vFnWg4

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