The Philadelphia SIDS Cluster
In the summer of 1963, in the area of Philadelphia, Pennsylvania medical examiner Dr. Joseph Spelman saw an unexpected increase in “crib deaths.”
During the last two weeks of June, Dr. Spelman reported that 30 apparently healthy infants were put to bed for the night and died suddenly and unexpectedly. He commented that this was a “new puzzle for medical researchers.” It would eventually be known as Sudden Infant Death Syndrome, or SIDS.
Dr. Spelman commented that the average number of such deaths during the summer months was about 5, so the occurrence of 30 deaths in a two-week period must have been very alarming.
Like so many infants that die in this manner, he was unable to find a cause.
Dr. Spelman confirmed that some of the deaths coincided with a heat wave, but that there were a few more deaths when there was no heat wave, he noted. The temperature at the end of June that year ranged from 90° to 97°–not particularly unusual. There have been hotter summers.
Still, there is some evidence more recently that SIDS, or crib deaths as they would have been known at this time, may have some correlation to outside temperatures.
A 2015 study of data in Montreal (which doesn’t typically get hot….seasonal high for July is 80°F) found that temperatures higher than 84°F were associated with 2.78 times greater odds of sudden infant death syndrome compared to 68°F (in their weird computational model). Their actual data though still shows that more SIDS occurs in October compared to July, etc. so its confusing how their modeling finds a different odds ratio. This study excluded all winter months, so it seems like they are trying to show a correlation between unexpected high temperatures in a population not suited for high temperatures and even though they said they proved it, their tables don’t demonstrate that. They even cite a Taiwan study that found that low temperatures are the most correlated to SIDS and that high temperatures are the least correlated. Either way, Philadelphia averages much warmer, and has had even higher temperatures both before 1963 and after, and did not see the same spike in crib deaths.
Another question I have is how does air pollution in the environment affect SIDS (air pollution whether chemical or organic such as mold, is related to so many health conditions, including respiratory conditions) these environmental pollutants are no doubt more common in heat waves. This may be a confounder for high temperatures. A quick glance at Philadelphia from 1963 finds that sulfur dioxide levels in the City of Philadelphia fell almost by half from 1956 to 1963, so it had less air pollution that year than previous years.
The idea that a heat wave would alone cause a spike in crib deaths just doesn’t fit the overall epidemiological data: ‘crib deaths’ have always been less frequent in the summer months, when it’s warmer, and much more common in the winter.
This clear seasonal preference during the cold winter months aligns with the seasonality of upper respiratory infections. Many of the infants would have a preceding “cold,” and prone sleeping position seemed to facilitate the infection, reduce ventilation, contribute to overheating–or all three. Interestingly, Torch presented material in 1982 that found that seasonal fluctuations were more common in unvaccinated infants, whereas vaccinated infants did not have the same seasonal fluctuations.
We do know body temperature relates to SIDS, and overwrapping and overheating are both factors that increase risk for SIDS, and using a fan is associated with a lower risk. In the summer, it’s less likely that a parent would overwrap an infant, or use thick bedding–probably one reason why SIDS was less frequent in the summer.
What about vaccines?
One important confounder for overheating or raised body temperature is: vaccination. Over 31% of infants experience fevers within 48 hours of each dose of the old DPT vaccination. Infants cannot thermoregulate the way an adult can, and young infants can’t simply remove warm covering or bedclothes the way an adult can. A parent may not notice a fever that spikes throughout the night, and infants who die of SIDS are often found in sweaty bedclothes.
This earlier version of the DPT vaccine was very reactogenic, and its unacceptably high rate of adverse reactions is the exact reason many developed nations eventually (after decades) switched from a whole-cell version of the vaccine, to the acellular pertussis vaccine, known as DTaP.
In 1991, the Institute of Medicine (IOM):
“found that the evidence is consistent with a possible causal relation between DTP vaccine and acute encephalopathy, although it is insufficient to establish causality.”
The more you start researching vaccines, you will find that certain highly used key phrases appear over and over “cannot establish causality,” “unable to find a link,” “insufficient evidence,” “no evidence of a link,” “is not proven.” What these phrases are saying is that they can’t or don’t know, and this language covers them legally, ethically. They can at some later date say, “they didn’t have all the evidence, they didn’t know.” Science evolves. Our understanding evolves. Well, sometimes a mother’s intuition knows the answer. Finding the data to prove is one thing, but it’s not everything.
Could vaccination have played a role, either directly or indirectly, in this SIDS cluster? What would cause so many “well infants” to die suddenly in their cribs in this one geographical area?
So many questions such as:
- How were vaccines refrigerated in the 1960s?
- How did medical personnel know that the vaccines were being properly stored?
- Also, this was during an era of constant contamination. There is almost no way to guarantee the amount of toxoid in the vaccine, contaminants, hitchhiker viruses, quantities of aluminum and thimerosal, etc.
- Did infants get the Salk inactivated polio vaccine that was contaminated with SV-40 or something else?
- Was this a “hot lot”? Did it become a “hot lot” from the heat or some other reason?
- This was also before widespread use of disposable syringes. Did that play a role?
More infants to be immunized
While the DPT vaccine (diphtheria-pertussis-tetanus) was introduced to the public around 1948, it wasn’t routine for the majority of infants. Socio-economic factors played a role, and often more well-to-do families were able to vaccinate, and even just see a pediatrician.
Then in October 1962, the “Vaccination Assistance Act of 1962” was signed into law, allocating $14 million in funding toward community vaccine programs that focused on infants and children, primarily children under the age of 5. This would increase the availability of vaccines to a range of families of lower socioeconomic status, including infants who may be premature, sickly, and overall not as healthy as more wealthy counterparts.
The first DPT vaccine would be given sometime after 6 weeks, usually around 2 months of age, and then again at 3 months and then at 4 or 5 months, although there was no national recommended schedule and pediatricians often had “their own schedule.” At this time it wasn’t unusual to give each vaccine dose one month apart.
Vaccine coverage for 1963 shows that around 71% of infants or children had 3 doses of DPT vaccine, up from 67% the year before.
This is a sample immunization record from the Children’s Bureau Publication Infant Care that may have been given to new parents:
A New Mysterious Killer
Because of growing concern of the uptick of deaths in “well infants”, in 1963 the first international conference on SIDS took place in Washington State and for the first time pathologists and doctors and medical examiners gathered together to try to understand sudden infant death and identify some of the risk factors.
Another conference would take place in 1969, and finally SIDS would have a name and definition, and eventually an ICD code where it would actually be counted in the National Vital Statistics–although that wouldn’t happen until 1974.
Then in 1978 another SIDS cluster happened, this time many of the infants who died had received the same lot of vaccine. This is known as the Tennessee SIDS cluster. After this event, vaccine makers decided to split up vaccine lots and distribute them more evenly over the country, so as not to inadvertently create a “hot lot” or a SIDS cluster that could be linked back to a specific vaccine lot. Prior to this though, back in 1963, vaccine lots would have been geographically together, thus leading me to wonder if this sudden uptick in “crib deaths” is indeed a historical “hot lot” that has yet to be identified and investigated?
It is unclear if any of the deaths during June 1963 in Philadelphia were directly related to vaccination, or some other environmental cause, but if you are a sibling or a parent of an infant that died of “crib death” during this time please share your story below. Help me bring this story to light.
To read more about SIDS, please visit the SIDS Facts page.
