A hypothetical situation: A child dies suddenly. There is no obvious cause of death. They had, though, been vaccinated that very day. What conclusion do people reach for?
I would argue that a single unexplained death – no matter how tragic and no matter how ‘available’ – can tell us very little indeed about vaccination.
Sudden infant death syndrome (SIDS) and sudden unexplained death (SUD) are not so common as to be described as an “everyday occurence”, but are not so very rare either. Vaccination, on the other hand, is extremely common indeed. There are a number of vaccinations given to children, and some of these are given repeatedly – for example that for diphtheria tetanus and pertussis (DTP/DTaP). These vaccines are given to the vast majority of children in most countries fortunate enough to have a decent healthcare system.
It seems likely that some SIDS deaths will occur on the same day as vaccination purely by chance.
Researchers looked at vaccination and SIDS in Australia. They concluded that while SIDS coinciding with vaccination would be infrequent, it would likely happen at least once in any given year in Australia purely by chance alone.
The probability of recent vaccination and SIDS coinciding varied by age and day of the week of death. The overall estimated probability of vaccination within the last 24 hours for a child who has died of SIDS in Australia is estimated as 1.3%. In the last 48 hours, it is 2.6%. With the average number of SIDS deaths for the period 1997-2001 equal to 130 cases per year, we estimated that a case of SIDS will occur when vaccination was given in the last 24 hours in 1.7 cases per year and within 48 hours in 3.5 cases. [Link]
This means that of 130 cases of SIDS per year, one or two cases will likely coincide with a vaccination given that very day. This is purely due to chance and means nothing in terms of vaccine safety – the vaccination and the death are unrelated. It is also worth pointing out that the other 128 cases of SIDS will not coincide with vaccination. It seems that we must look elsewhere for the cause of SIDS.
Here, we have a case-control study looking at SIDS and SUD:
We identified 114 cases of SUD aged between 30 and 90 days and 341 live controls matched for age and sex and born in the same maternity unit as the case. DTPP±Hib immunization did not increase the risk of SUD (OR 1.08) (95% CI 0.49, 2.36) in children under 3 months of age when adjusted for sleeping position, illness in the week before death, maternal tobacco consumption, birth weight, type of mattress, breastfeeding and sex. However, low birth-weight (6.53 [2.29, 18.9]), multiple birth (5.1 [1.76, 15.13]), no breastfeeding (1.77 [1.1, 2.85]), prone sleeping position (9.8 [5, 8, 18, 9]), soft mattress (3.26 [1.69, 6.29]), recent illness (3.44 [1.84, 6.41]) and parental smoking (1.74 [1.2, 2.96]) were confirmed as risk factors in early SIDS. [Link], [PDF].
No increase in risk of SIDS is seen for DTPP±Hib immunisation. The researchers do, though, find other risk factors for early SIDS.
It’s perhaps worth noting that in the discussion section of the second paper, the authors write: “Moreover, recent epidemiological evidence indicates that infants immunized against DTP are perhaps at decreased risk of SIDS (25, 26).” Here are references 25 and 26:
25. Mitchell EA, Stewart AW, Clements M. Immunisation and the sudden infant death syndrome. New Zealand Cot Death Study Group. Arch Dis Child. 1995;73:498–501. [PMC free article] [PubMed] [Link]
26. Essery SD, Raza MW, Zorgani A, et al. The protective effect of immunisation against diphtheria, pertussis and tetanus (DPT) in relation to sudden infant death syndrome. FEMS Immunol Med Microbiol. 1999;25:183–192. [PubMed] [Link]
The date of the Guardian article is given as 29 January 2007. The Australian research on SIDS, coincidence and vaccination is from 2005. The case-control study I link to is from 2001, and the two references cited to support the statement that “epidemiological evidence indicates that infants immunized against DTP are perhaps at decreased risk of SIDS” come from 1995 and 1999.
All the research I have alluded to in this blogpost was available in 2007 when the Guardian article seems to have been written. None of it was referred to. Instead, the journalist wrote this:
The pathologist told the parents that their son had died of cot death. They didn’t believe it, and they still don’t. Hours before his death, Christopher had been given a triple vaccination.
I don’t think it’s helpful to publish an article implying a link between vaccination and cot death, SIDS, or SUD – particularly when the article in question fails to even mention the chances that vaccination will coincide with a case of SIDS and fails to refer even tangentially to the epidemiological evidence relating to vaccination and risk of SIDS.
Vaccines are often linked to diseases or symptoms. However, when researchers investigate these apparent links they very often turn out to be spurious:
During recent years a scala of diseases or symptoms have been associated with vaccination (presumed side effects). Careful and extensive investigations have shown that such hypotheses could not be supported. Examples are allergic diseases as asthma, diabetes mellitus, multiple sclerosis (after hepatitis B vaccination), autism and inflammatory bowel disease (after MMR vaccination) and sudden infant death syndrome. [Link]
SIDS and DTP-IVP vaccination:
The only specific risk factor for SIDS is age (2-4 months), though birthweight, prematurity and the younger age of the mother increase the probability of dying in the same manner as for accidental causes and all other postneonatal deaths. […] No significant differences were found in the DTP IPV immunization rates between SIDS and other causes of death or between SIDS and living controls. [Link]
In March 1986 five sudden infant deaths were reported, following the diphtheria-tetanus toxoids-pertussis and inactivated poliomyelitis virus (DTP-IPV) immunization of the infants concerned. An epidemiological study was carried out in order to investigate the possibility of a relationship between this immunization and sudden infant death syndrome (SIDS). A detailed examination of the five cases had been carried out by a doctor. An exhaustive survey of all postneonatal deaths occurring between January and March 1986 was conducted and also a matched case-control survey. No significant differences were found in the immunization rates between SIDS and other causes of death, nor between SIDS and living controls. These results are compared with the results from previously published studies on the topic. [Link]