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The pertussis vaccine and allergy - First part

Some parents fear that vaccines can cause allergies including asthma.

It 's a very broad topic so the split in different places starting from the cell pertussis vaccine (whole bacterial cell, killed), which is what is most often charged by vaccinia, with regard to allergies. (In most industrialized countries for years using the acellular pertussis containing only parts of the bacterium, highly purified).

For them it all seems very simple. Pubmed go up, do a search on the topic of study required (for example, "DPT immunization asthma"). Read the abstracts and select those in which it is reported a positive association between the vaccine and asthma, without checking the quality of the study.

cite even ignoring case report the fact that the single case report may represent a given unusual compared to the average population and therefore can not be taken as a proof of a causal relationship, the latter is true, moreover, also for some types (drawings) of epidemiological studies that can to establish an association between the EPlace a risk factor and a disease but not to prove a causal link.




Other studies, namely those who have found no association between vaccines and asthma, or even protective association, are simply discarded. They do not even need to obtain the full text studies and read them carefully to assess their quality, the advantages and limitations. Do not have to read books on the subject , to learn how to evaluate scientific work and what must be done carefully.

not need it because they know that the vast majority of their audience will never go in person to check the claims, but just look at the numbers that show the citations of scientific studies that are at the bottom of the page. These quotes are denser, more science seems to him the book. People between their public control and really read the full texts of the studies cited, you can probably count on the fingers of one hand.

may present their views in this way surface only because people let him . Many simply seek confirmation for their opinions and most do not understand how scientific progress. Those who believe that vaccines are bad, buy books or attend sites which are supposed to be written by people who share their views. In reality they do not care what they say truly scientific studies cited. The only thing the press is to feel reassured and strengthened in its belief and placate their consciences. This mental laziness however, may have high costs for the individual and for society. We should learn to be more skeptical and honest with themselves, especially when is the health and lives of their children.

think about it, if vaccinia to be consistent, should not use scientific studies to prove their opinions because their main feature is the rejection of scientific evidence. But obviously know very well make a habit of people not to check the sources cited and the psychological impact that science has a slew of citations to the player.

To explain the way in which the vaccinia unacceptable use - despite everything - the scientific literature, I see no other way to look more closely at the studies cited by them and especially those who do not cite them.

I understand that not everyone is of interest approfondire la lettura degli studi scientifici, ma le vie sono solo due:

1) accettare a occhi chiusi gli argomenti proposti

2) controllare personalmente le fonti citate

Non vedo altre vie. Per fare le cose per bene bisogna vincere la pigrizia mentale.

Quindi ecco l'inizio dell'approfondimento sulle vaccinazioni e le allergie.

Come filo rosso mi servirò, come sempre, del libro "Bambini super-vaccinati" del dott. Eugenio Serravalle. Questo libro è molto prezioso per il mio blog perché è pieno di fili che pendono (come si esprimerebbe Poirot) che mi fanno venire una voglia irresistibile di annodarli.

Sfoglierò il libro e progressivamente commenterò le varie affermazioni che si riferiscono alla questione vaccini e allergie.

A pagina 37 si incontra per la prima volta questo tema:

Uno studio giapponese ha dimostrato che tra bimbi vaccinati contro difterite-tetano-pertosse (DTP) e bimbi non vaccinati erano presenti significative differenze di frequenza per le patologie allergiche.

e poi segue una tabella con le percentuali (vedi abstract dello studio).

Ed ecco il riferimento:

Arerugi. 2000 Jul;49(7):585-92.

[ The effect of DPT and BCG vaccinations on atopic disorders ]

[Article in Japanese]

Yoneyama H et al.

Department of Pediatrics, Tokyo Metropolitan Government Hiroo General Hospital.

The work cited by the author is not only a "study Japanese but it is written in Japanese . I suppose Dr. Serravalle has read only the abstract, unless you know the Japanese language. The same is probably true also for the myriad of other vaccinia mentioning here (just do a search on Google by putting "the effect of DPT and BCG vaccinations on atopic disorders). Practice is only mentioned by vaccinia and proponents of various types of alternative medicine.

You should never use a scientific research by reading only the abstract because This makes it impossible to assess their quality.

However, dall'abstract should already be in doubt about the reliability of the result. The study included all children of a Japanese island. The possible association between the DPT vaccine and asthma, atopic dermatitis and allergic rhinitis was limited to children between 0 and 3 years. A total of 82 children of which 39 vaccinated and 41 unvaccinated. Even these very small numbers make it clear that it is not very appropriate to draw conclusions. These data deserve a table in a book? Not really.

I managed to find some clues that go beyond the abstract. Researchers very meticulous ( as can be seen reading their research ) had included this in their meta-analysis study and requested the translation from Japanese into English. Then they gave, as all studies included in the research, evaluation and a brief description of critical points (see table 2 ). Well, score one of the lowest quality is expected, among other things because they lack reliable information on the diagnosis that was simply based on a questionnaire filled out by parents.

So this is a study of low quality, on a very small population of a remote Japanese island, whose data are based on one of the least reliable source, not a medical diagnosis.

compare, just for curiosity, this study with one of the many others that have been made in recent years. Pediatr Infect Dis


J. 2002 Jun; 21 (6) :498-504.

Childhood vaccinations and risk of asthma.

DeStefano F et al.

Centers for Disease Control and Prevention, Atlanta, GA, USA.


This is an observational cohort study. It means, in this case, a group of children vaccinated and a group of unvaccinated children, were followed for a certain period of time (a total of 1991 to 1997) and compared their risks (two groups) to develop asthma.

In total, the study by De Stefano et al. were involved 167,240 children who were followed from birth for a minimum of 18 months up to a maximum of 6 years. The data on the vaccination of children was obtained through the Vaccine Safety Datalink Project - a project involving four Health Maintenance Organizations (HMO, an HMO is a network of doctors, pharmacies, hospitals) - which allows you to link together some clinical database allowing to collect the data of patients with their medical history (vaccinations, disease diagnosis, etc.).

for 18,407 children (11% of the total) has been confirmed the diagnosis of "asthma."

Overall, children immunized against DPT, OPV (oral polio) and MMR (measles, mumps, rubella) were not significantly more likely to develop asthma than children not vaccinated. Are significantly more at risk children vaccinated against haemophilus influenzae B (HIB) and hepatitis B.

In reading these results, however, must take into account that observational epidemiological studies such as De Stefano et al., Evaluate only the association between risk factors and disease (not establish a causal relationship between vaccination and asthma), and may present problems of recruitment of subjects. One of the most common is the possibility that some patients have undetectable change in this way the risk of developing the disease in a group (vs children vaccinated. Unvaccinated children).

In this case the authors of the study showed a possible error of the method of selection of children vaccinated and diagnosed as asthma. Some children, after birth, may not have been taken, for various reasons, the Health Maintenance Organization (HMO) members of the project, but escaped observation, may have been vaccinated by other doctors and not be vaccinated solo per gli autori dello studio; oppure potrebbero avere avuto una diagnosi di asma e rientrare invece tra i soggetti sani. Per aggirare questo problema De Stefano et al. hanno condotto una sotto-analisi solo sui bambini portati almeno due volte nel primo anno di vita in uno degli HMO del progetto. Per individuare questo sotto-insieme è stato necessario recuperare le informazioni relative al numero di incontri, informazione che era disponibile solo per due degli HMO per un periodo di tempo limitato. Questi vincoli hanno ridotto la numerosità della coorte a 17.740 bambini. Come cambiano i risultati?

Innanzitutto, nel periodo in cui erano disponibili i dati sul numero di incontri nei due HMO, il numero totale di bambini tracciati risulta pari a 17.949. The risks for these children are perfectly comparable with those obtained on the entire cohort and above. Restricting the analysis to the 17,740 children who had at least two visits in the first year of life, de Stefano et al. observed a significant reduction in the risk of asthma among vaccinated for HIB, hepatitis B and OPV.

After this tedious explanation we come dovrrebbe spontaneous question:

1) Why Dr. Serravalle said that the DPT vaccine increases the risk of allergies and cites a small study of very low quality, based on a total of 81 children and fails to DeStefano in the 2002 points from birth to 6 years up to 167,240 children well? This second clearly merits more study would have to be taken into consideration (especially if you see him in the general context of all studies on the subject made to date)

Maybe he did not find during your research? No, this is not the explanation, because on page 154 cites precisely this work of DeStefano! Perhaps you guess in which section ... in the course of hepatitis B:

children vaccinated until the sixth year of life suffer from bronchial asthma, with an incidence of 10% higher than the other unvaccinated children.

So not only did not inform their readers of the other results of that study, but does not mention even properly the result concerns that the vaccine against hepatitis B. Although this study had found a combination of an increased risk of 10%, it would be more correct to point out that the study demonstrates an association but can not establish a cause and effect. These types of study have some limitations related to (i) the possible presence of confounding factors, that risk factors other than the one studied that may be responsible for the association observed, (ii) problems of misclassification of disease due to different definitions (eg There are different definitions of asthma that differ according to treatment, presence or absence in co-morbidity), (iii) the difficulty of having information complete per tutti i soggetti quando si utilizzano basi dati amministrative. Come si è visto, quando un probabile problema di selezione dei soggetti è stato preso in considerazione, ricorrendo ad una sotto-analisi, l'associazione non è più risultata significativa.

Inoltre, per coerenza il dott. Serravalle doveva presentare anche gli altri dati dello stesso studio e aggiungere che era stata trovata nessun'associazione tra vaccini DPT, OPV, MPR e l'asma. Ha invece preferito non darne informazione ai lettori e utilizzare solo quello che gli serviva per "dimostrare" che il vaccino contro l'epatite B può causare l'asma, spaventando inutilmente i genitori.

Ringrazio Bodegones for collaboration in the presentation of the results of the study by De Stefano et al.;