Holford Watch: Patrick Holford, nutritionism and bad science

Former Visiting Professor Patrick Holford is still Head of Science and Education at Biocare so presumably they must believe that he enhances their reputation and scientific credibility. We look at Holford’s advice in “Vaccinations: what every parent needs to know” in 100%health Newsletter, No. 46, July 2008, pp. 5-8.^[a] We focus on his coverage of the issue that the timing of vaccination is an asthma risk.

In the New 5-in-1 Vaccination section, Holford acknowledges that Pediacel, the 5-in-1 vaccine in use in the UK that combines polio, whooping cough, diphtheria, tetanus and Hib, contains updated polio and pertussis vaccines (albeit, he says “safer” rather than “updated” which is a little emotive). Holford then expresses concern about the association of asthma and the timing of vaccinations.

However, research published in the Journal of Allergy and Clinical Immunology has shown that the risk of childhood asthma doubled when the first dose of diptheria, whooping cough and tetanus was given at the recommended time (ie two months old) versus being delayed by more than two months (ie at least four months old).^[1] In addition, the risk decreased with delays in giving all of the doses. Although this research looked at a slightly different type of whooping cough vaccine, the new 5-in-1 vaccine has polio and Hib added, so the load on a child’s immune system is further increased…

You could decide to delay giving the first dose of this vaccine until your baby is at least four months old, and then further space out the two follow-up jabs over this first year.

patrickholford.com also offers a paywalled Q&A with Dr Richard Halvorsen. Oddly enough, Holford is usually so hypersensitive about other people’s potential conflict of interest that he identifies them when none exist and even indulges in a conspiracy theory when it serves his purpose. However, although Holford mentions that Halvorsen operates the private vaccination service babyjabs.co.uk he doesn’t acknowledge that this might be seen as a conflict of interest that influences Halvorsen’s advice.

Q: Would you condone not vaccinating children at all, especially if they have a healthy diet/lifestyle? Or do you believe there are certain vaccinations, which are vital for children in our modern day? Also, don’t vaccinations compromise our immune systems?

A: I do not share the view of many of my medical colleagues that full immunisation is essential for a child’s health. If parents make an informed decision not to vaccinate their child, then I do not believe this is irresponsible…

There is evidence that vaccinations can have adverse effects on our immune systems – for example, delaying giving a baby vaccines by a few months can reduce the risk of asthma by more than half.

One essential problem is that Holford has not previously given an appropriate or accurate overview of the research that he cites in support of his anti-vaccination advice: see e.g., his misinformation and partial interpretations for the whooping cough vaccines and his alarmist account of aluminium in vaccines. Such errors are not infrequent in Holford’s work and reduce any confidence that some might have in his recommendations.

However we shall restrict ourselves to examining the claim about the association or timing of vaccinations and the risk of developing asthma. Unsurprisingly, Holford has selected a paper that supports his stance although the research canon on this topic also contains well-conducted cohort studies that report results that don’t support his advice. Both Halvorsen and Holford rely upon McDonald et al’s report for the Manitoba Cohort^[1] that reported an association with asthma and both neglected to mention that the analysis of Maitra et al.^[2] of a UK cohort, variously known as ALSPAC or Avon, does not support their advice. Maitra et al. concluded:

These findings confirm and extend our previous observations of the lack of an independent association between pertussis vaccination in infancy with inactivated, whole cell vaccine and the subsequent development of asthma or atopy during later childhood.

There are several relevant studies and the picture is mixed so there are reports of both positive and negative associations; there are suggestions that the vaccine might be linked to asthma or atopy in some studies (possibly provocative) but found to be preventative for it in others. It is fortunate that Balicer et al. have performed a helpful meta-analysis: Is Childhood Vaccination Associated With Asthma?^[3]

It is important that researchers clarify this issue, because unless refuted, the perception that immunization causes asthma may become a significant determinant of parents’ attitudes toward routine vaccination of their children…

The aim of this study was to systematically review the literature on the possible association of whole-cell pertussis and BCG vaccination in the first year of life with the incidence of asthma in childhood and adolescence and to perform a meta-analysis of the relevant studies.

The authors screened >2000 citations and whittled them down to 11 studies that met the following criteria.

• Randomised, controlled trial or birth-cohort study, either prospective or retrospective.
• Studies directly compared vaccinated and unvaccinated children.
• Vaccination status was validated by medical records.
• Pre-determined criteria to define asthma.

There were 7 studies of (whole-cell) pertussis vaccination (a total of 186,663 children) and 5 studies of BCG vaccination (a total of 41,479 children) that met the authors’ inclusion criteria.^[b]

Balicer et al. concluded:

The currently available data do not support an association, either provocative or protective, of BCG or whole-cell pertussis vaccination in infancy and risk of asthma in childhood and adolescence. These findings could be used to relieve parental concerns that could otherwise lead to vaccination refusal.

The lack of robustness of the results of the sensitivity analyses of pertussis vaccination and the multitude of potential biases in studies that have used a birth-cohort design stress the need for additional adequately controlled, large-scale studies.

Tye of Stifled Mind has some pertinent comments about bias in studies that involve birth cohorts: Vaccination and asthma shown to be unlinked. Tye discusses a report from a mini-symposium on birth cohort studies.^[4]

The report detailed some difficulties encountered including changing nursing staff over the years which led to different bookkeeping and even patient evaluation scores. Racial differences need to be accounted for by including as many different genotypic backgrounds. The births need to be carefully selected to be evenly distributed over a 12 month period in order to account for seasonal affects. One of the largest problems is lost subjects, those who tend to not be affected by a disease will more regularly drop out of the study, pushing a bias towards those who are affected and are more likely to continue making their appointments. Interestingly enough it was found that as the personnel at the study centers changed the loss of subjects jumped significantly.

Epiwonk walks us through the meta-analysis: Childhood vaccination is not associated with asthma. Epiwonk adds in some discussion of caveats and additional studies (including the Manitoba Cohort^[1]) before reaching this conclusion.

A recent systematic literature review of high-quality studies that directly compared vaccinated and unvaccinated children, validated vaccination status by medical charts, and used preset criteria to define asthma found no association between childhood vaccination and asthma.

McDonald et al^[1] reported an interesting finding with the reduced risk of childhood asthma and an association with a delay in DPT vaccination. However, the association has yet to be confirmed elsewhere and the authors offer a considerably more nuanced interpretation of their results and their implications than Holford and Halvorsen:

To our knowledge we are the first to report that delay in adminstration of the first dose of DPT immunization is significantly associated with reduced risk of developing asthma in childhood…

Our data indicate that the reduction in asthma risk for the second and third doses was primarily a result of the delay in the first dose, because no statistically significant differences in asthma risk were seen with delays in the second and third doses in the absence of delays in the first dose. However, among children with delays in all 3 doses, the likelihood of asthma was further reduced to 60%…

Whole-cell pertussis DPT is no longer used in many countries, but our study generates some interesting hypotheses for the biological mechanisms behind early childhood vaccination and the development of asthma…

Our study would need to be repeated in a later birth cohort to assess the effect of the acellular pertussis vaccine because the DaPT vaccine has been found to be less reactogenic, with a lower incidence of adverse events…It is premature to make recommendations until these findings have been confirmed with the DaPT vaccine, and the benefits of altering immunization schedules need to be weighed against the risks. [Emphasis added.]

Quite. It may seem tedious but it is essential to learn:

• whether these results are replicated in other birth cohorts
• whether or not acellular pertussis vaccine delivers different findings when compared to whole-cell pertussis vaccine
• whether there are risks associated with delayed vaccination.

We have contacted the authors with some additional questions about vaccination, prematurity, low birth weight and whether there were any differences relating to mothers being aboriginal or non-aboriginal women.

The clearest and repeated finding from various analyses seems to be that there is no evidence for an association between vaccination and asthma when studies are of an appropriately high quality and evaluate vaccinated and unvaccinated children, validate vaccination status by medical records, and uses pre-determined criteria to define asthma. McDonald et al. have reported some interesting associations between the timing of DTP vaccinations and asthma diagnosis by the age of 7 but they are considerably more nuanced about their interpretation than other commenters. The authors specifically caution that it would be premature to consider altering the vaccination schedule without further studies and evaluation.^[1]

There is little evidence of similar nuance in Holford or Halvorsen’s recommendations. Nor has either of them provided:

• an approximate costing for how much it would cost to pursue their recommended vaccination schedule of single vaccines
• an estimate of the relative risk of leaving children unprotected from preventable illnesses during their extended schedule – illnesses that carry risks of morbidity and mortality (e.g., whooping cough^[c]).

As ever, if parents have concerns about vaccination, please talk to your Health Visitor, GP or other appropriate healthcare provider. HolfordWatch is exploring the evidence that Holford and Halvorsen cite in support of their vaccination advice and we are demonstrating that they may be interpreting it in a way that: cherry-picks work that supports their stance and ignores that which doesn’t; extends beyond the scope of research involved; and directly disregards authors’ cautions about the significance of their findings. Decisions should be taken with as much clear information as possible, the process is hindered when interpreters such as Holford omit to mention relevant information or distort the research.

We should comment on other canards such as “[t]here is evidence that vaccinations can have adverse effects on our immune systems” that sound ominous but may be meaningless and lack any context to compare them to the risks of preventable childhood illnesses. Plus, we are intrigued as to whether Holford and Halvorsen consider that their flawed interpretation of research is an adequate basis for parents to make an “informed decision not to vaccinate their child”. However, we hope to have a guest blogger who will shortly be bringing another perspective on the Holford and Halvorsen vaccination advice.

References

[1]McDonald KL, Huq SI, Lix LM, Becker AB, Kozyrskyj AL. Delay in diphtheria, pertussis, tetanus vaccination is associated with a reduced risk of childhood asthma. J Allergy Clin Immunol. 2008 Mar;121(3):626-31.
[2] Maitra A, Sherriff A, Griffiths M, Henderson J; Avon Longitudinal Study of Parents and Children Study Team. Pertussis vaccination in infancy and asthma or allergy in later childhood: birth cohort study. BMJ. 2004 Apr 17;328(7445):925-6.
[3] Balicer RD, Grotto I, Mimouni M, Mimouni D. Is childhood vaccination associated with asthma? A meta-analysis of observational studies. Pediatrics. 2007 Nov;120(5):e1269-77.
[4] Nickel R, Niggemann B, Grüber C, Kulig M, Wahn U, Lau S. How should a birth cohort study be organised? Experience from the German MAS cohort study. Paediatr Respir Rev. 2002 Sep;3(3):169-76.

Notes

[a] Holford thanks Melody Mackeown of Natural Nutrition for “all her excellent research”. However, it is unknown whether Holford’s errors are attributable to Mackeown’s work or his use of it.
[b] One study examines both so is counted twice.
[c] According to NHS Immunisations: How Serious Is Whooping Cough?:

• more than half of babies under 1 with whooping cough are hospitalised
• the majority of pertussis cases involve some degree of collapsed lung and/or pneumonia
• about 1 in every 500 die from the illness, and the risk is highest in younger babies
• half of the deaths are attributed to pneumonia
• up to 1 in 50 can suffer convulsions
• around 1 in 1000 may develop encephalopathy (brain disease).

Serious illness is less common in older children however whooping cough can still be debilitating, and it is disruptive both for them and other family members.

BPSDB