Earlier this week the Otago Daily Times, locally known as the ODT, had on page nine an article titled Whooping cough vaccination ‘cocooning’ call.
In New Zealand, at this time, we have a number of vaccine-preventable illness in the community. One is meningococcal meningitis (strain C). Rubella is another. Whooping cough, or pertussis, is yet another.
The title and overall thesis of the article in the ODT are straight-forward enough. Family members visiting their new grandchild might get vaccinated to prevent accidentally passing the disease on to the little one.
It’s a similar to a key concept behind rubella vaccination. Rubella infections in a pregnant mother have serious implications for their unborn child. Vaccinate the community and you prevent rubella infection being passed to mothers.
Pertussis occurs at all ages, but it’s effects are most severe in the very young. The older population is effectively a reservoir of disease that can infect infants. (From Heininger, Update on pertussis in children.) It is a very contagious disease, one that readily passes between people, ’infecting 70 to 100% of susceptible household contacts and 50 to 80% of susceptible school contacts.’ (See: IMAC pertussis page.)
In the middle of the ODT story the journalist, Eileen Goodwin, elected to offer ‘balance’ in the form of a quote from the Immunisation Awareness Society (IAS).
Invercargill-based Michelle Rudgley, of the Immunisation Awareness Society, was concerned by the push for more vaccinations. “One day they are really going to have to accept that the pertussis [whooping cough] vaccine is useless and no matter how many boosters you have it is not going to stop the occurrence of whooping cough and the best bet is for parents to educate themselves on how to look after their children should they develop it. “The best way to do that is high doses of vitamin C. It is a toxin-mediated illness, so vitamin C is the way to go and lots of it,” Ms Rudgley said.
I’m not very keen on uncritical reporting, so let’s look at Rudgley’s claims for ourselves.
I’d usually recommend first looking at the general style and line of advice of a source to get a feel for the soundness of their claims (e.g. visiting the IAS website), but instead let’s look at the claims on their own merit.
I’m not a specialist in pertussis or a clinician. What I’d like to do is to use local material in a similar manner as a non-specialist might, say a journalist, myself (!), or visitor to Rudgley’s site – a sort-of worked example of briefly scoping Rudgley’s claims out.
My exercise shows that readily-found sources, including one Rudgley recommends, contradict what she offered the journalist.
Rudgley writes that ’the pertussis vaccine is useless’.
First we’d want to know what she means by ‘useful’. For the sake of this article, let us assume she means ‘reduction in the number of cases of pertussis in young children’. Other measures might be the number of deaths in infants, or cost to the country, and so on.
This document is really intended for clinicians (i.e. doctors), but it has a lot of helpful material. It’s much easier to read than the original research literature, providing a useful half-way step between the research literature and ‘layman’ summaries. Each chapter is available as a separate PDF file, including the one for pertussis.
Of the effectiveness of the pertussis vaccine the MoH Immunisation Handbook 2011 says (page 143, paragraph 4),
That immunisation made a considerable contribution to the reduction in pertussis mortality was demonstrated in a review of the infant pertussis death rate in the US from 1900 to 1974. Had the decline in mortality from pertussis continued at the same rate as it did from 1900 to 1939, there would have been 8000 deaths from pertussis in the US between 1970 and 1974 rather than the 52 deaths that occurred.14
and later (page 135, paragraph 2),
The introduction of mass immunisation was associated with a 5- to 100-fold reduction in pertussis incidence in Canada, England and Wales and the US between 1930 and 1980.25—27
The source Rudgley advocates indicates that the pertussis vaccine is of use, contrary to what she offered to the journalist.
The Immunisation Advisory Centre, IMAC, offers information on vaccines and vaccine-preventable illness for both parents and health professionals.
The IMAC page on pertussis offers this for efficacy and effectiveness:
- More than 80% through to 6 years of age, without boosting for some 3 or more component vaccines. Refer to manufacturer for efficacy data specific to preparation used.
- Immunity wanes 5-10 years after primary or booster immunisation.
- Studies on additional booster doses given during adolescence and adulthood suggest a protective efficacy of 32-99%.
Travelling away from New Zealand sources, this summary, titled Vaccines Refusers Are at Increased Risk for Contracting Pertussis, of Glanz et al’s study published in Pediatrics conclude their viewpoint writing ’Even so, the authors make the point that, given the relatively low rate of pertussis in the general population, almost all pertussis cases probably result from vaccine refusal.’ (A viewpoint this in an interpretation but importantly for the discussion here it is an informed interpretation.)
Rudgley writes ’the best bet is for parents to educate themselves on how to look after their children should they develop it.’
My reading of this is that she advocates not preventing children from getting ill–the aim of the vaccines–but dealing with it once they are ill.
This would presume that the illness so rarely causes serious harm as to not be a concern and that dealing with an ill child is of relatively little consequence.
In particular, carried with this statement, is a presumption that the illness causes less harm than the vaccine. If evidence showed that the illness caused more harm, then informed choice would be to use the vaccine.
Let’s briefly touch on each in turn.
Does pertussis so rarely cause harm as to not be a concern?
Since she is advocating that people not take the vaccine, we have to look at the rate of harm in absence of vaccination. We have already seen the MOH Immunisation Handbook 2011–that she recommends people read–state the rate of illness was higher before the vaccine was introduced.
New Zealand, like most countries, has researchers studying the vaccines used within their country. Grant et al’s research study (see references, below) on pertussis vaccination in New Zealand opens with,
Pertussis remains a severe disease in infants. As about two thirds of infants with pertussis are admitted to hospital,
Parents don’t send their children to hospital lightly. This by itself indicates that there is concern.
Two-thirds of infected children being admitted to hospital strikes me as very high. (Grant et al., do note that this is quite a bit higher than in the UK. I suppose Rudgley might suggest that better treatment of children might counter this; let’s leave that for when we look at her claim that high-dose vitamin C will treat pertussis.)
Grant et al’s study show that early immunisation is associated with a lower hospital admission rate.
What harm is caused?
The IMAC page on pertussis for parents summarises the effects of the disease as including:
- 0.1-0.3% risk of permanent brain damage for patients with paroxysmal cough
- Case fatality of 3.5% in hospitalised infants under 6 months.
Likewise, the IMAC for health professionals summarises mortality:
- 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.
More important is if the rate of harm is higher when vaccines are used compared to when they are not used – we’ll come to that soon.
Is dealing with an ill child of relatively little consequence?
This would be the impact on the family, their time, loss of income and so forth. I would have thought that it be straight-forward that dealing with any ill child has consequences. Pertussis infections run for several weeks (six weeks or so is an oft-cited figure), not a few days, and are followed by a convalescent stage that may last several months. I can only speak for myself, but it is hard to see that it would not be disruptive to a family.
The consequences for infants are more severe than older children or adults, and include death.
Because it is contagious, the long period of illness of older children or adults gives opportunity for them to pass the disease on to infants who are more vulnerable to it.
Does the the illness causes less harm than the vaccine?
One of the key arguments for vaccination is that, taken as a whole, the population is better off with the vaccine programme than without.
This does not say that individual cases of disease will not still occur, or that rare effects due to the vaccines will not occur. Everything we do in life has some risk. That’s as true for vaccines as anything else. It says that the overall health of the population is better with the vaccine programme than without it. It is the balance of the risks that is of the essence: which approach are we better taking?
Grant et al’s study show that delayed immunisation for pertussis is associated with a higher risk of the child being admitted to hospital. They find that ’fully immunised infants and children are 4-6 times less likely to be admitted to Starship children’s hospital with pertussis than [their] under unimmunised or under immunised peers.’ (Source Grant et al and IMAC.)*
This is one part of the ’equation’ – the rate of serious pertussis infection. (I write serious, as they’ve been administered to hospital.) Those who were vaccinated for pertussis were better off.
The other part of the equation would be the rate of ill effects from the pertussis vaccine.
Right at the bottom of the IMAC health professionals page it summaries the balance of risk, first the risks from the disease:
- 90% risk of contracting pertussis for non-immune infants.
- 20% of all adults and adolescents may be infected at one time.
- 0.1-0.3% risk of permanent neurological damage for patients with paroxysmal cough.
- Case fatality of 0.05% in hospitalised infants.
then the risks from the vaccine (the web page says that these rare reactions resolve spontaneously):
- Mild local or systemic reactions (0.8-62%)
- Severe local reaction (0.8-8.0%)
- Convulsions (0.00007%)
- Persistent screaming (<0.005%)
- HHE (<0.003%)
- Anaphylaxis (<0.00001%)
A key point is that the serious reactions to the vaccine–risks might be placed alongside the serious consequences of the illness–are much rarer than the serious consequences of the illness. Furthermore, the vaccine reactions apparently resolve spontaneously whereas the serious consequences of the illness are permanent.
MIlder reactions could perhaps be usefully compared with the weeks of looking after a sick child.
Rudgley mentions booster vaccinations. This might be read as her saying that these later vaccinations are not effective for the children they are given to. In practice a key reason for the booster vaccinations are so that older siblings are less likely to pass on the illness to their younger siblings who are more vulnerable to the disease.
High-dose vitamin C as a treatment
Finally Rudgley offers that high-dose vitamin C will put paid to the illness.
Vitamin C is offered to ’cure’ a vast array of illnesses. When you see a claim of a single treatment being able to treat a wide array of illnesses, it’s best to be very wary of the claim. Illnesses differ; it is expected that their treatments will differ too.
If Rudgley’s advice were sound, we’d expect to see research reporting that vitamin C can treat pertussis infections. To do this I’m going to have to look at the research literature as whole, rather than (mainly) limit myself to local sources as I have earlier.
Searching PubMed, I find just 25 articles containing the keywords ‘pertussis vitamin C’. This is very small number of articles given that pertussis is a major illness. (Searching using ‘pertussis’ alone gives 26,966 articles.)
Several of these articles do not relate to treatment of pertussis. Judging from the article titles, none of those relating to vitamin C as a treatment for pertussis were written after the 1950s.
When a line of thinking in research ‘dies’ from the research literature it most often it is because it has been rejected.
Of the ten articles, only three are in English – these few are from the 1930s. The first two English-language papers are by the same authors and thus not independent studies. These two papers claim a reduction in the illness through high-dose vitamin C treatment. The third, attempting to repeat this claim, finds no effect beyond statistical chance variation.
If there were support for Rudgley’s claim that vitamin C can treat pertussis, you would expect to see a body of references to it in the literature. A complete absence of reference to it in over fifty years would strongly indicate that there is no (substantiative) evidence to support her claim that high-dose vitamin C is a known to treat pertussis.
I don’t claim to be an expert in all of this, I’m not.
What I am struck by are two main things. Firstly, readily-available sources, most of them local, used in a fairly straight-forward manner contradict Rudgley’s claims, including a source that Rudgley herself advocates. Secondly, that a journalist uncritically repeated these claims.
One more titbit is worth mentioning. While the immunity offered by the vaccine is known to be limited, so is the immunity from natural infection. (Personal communication from IMAC.)
Earlier in the article I wrote that I’d usually recommend looking over the (IAS) site as a whole to get a feel for it or to test if a source offers sound comment (as a journalist might do before quoting them).
I would like to tackle this, but having written as much as I have already, I feel I should pass that baton onto those offering comments!
I would like to thank the prompt and excellent assistance of Helen Petousis-Harris of IMAC in writing this article.
I offered Eileen Goodwin–the journalist who wrote the article–an opportunity to explain ’why you considered it appropriate to quote Rudgley from IAS this article’, but I have not had a reply. [She has since replied, but offered no comment.]
* For clarity regards the citation ’(Source Grant et al and IMAC.)’: the source of the quote is correspondence with IMAC, the source of what the quotation summarises is Grant et al. – hence the ‘double’ citation.
1. I’m a ‘rubella kid’ myself, being born hard-of-hearing/deaf and partially blind as a consequence.
2. HHE = Hypotonic-hyporesponsive episode.
(Updated to add to footnotes: starred [*] footnote and that Goodwin has replied. Further updated to correct an typing error (‘replied’ for ‘relied’).)
I’ve deliberately used a small number of local sources, in an effort to limit myself to what might be reasonably found by a careful non-specialist (like myself!)
The MoH Immunisation Handbook 2011. Note that chapters are available as separate downloads.
Grant et al., Brit. Med. J. 326:852-2 (2003)
Heininger, Expert Rev Anti Infect Ther. 8(2):163-73 (2010), Abstract.
Basco, MedScape Pediatrics.
Other articles in Code for life: