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Sudden Infant Death Syndrome In VAERS: A Review

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By: Dr. F. Edward Yazbak

SIDS (Sudden Infant Death Syndrome) is, by definition, the sudden and unexpected death of an apparently healthy infant, whose death remains unexplained after the performance of an adequate postmortem investigation. This includes (1) an autopsy, (2) investigation of the scene and circumstances of the death and (3) exploration of the medical history of the infant and family. SIDS (ICD 9 Code7980) was defined as a syndrome in 1969. It is also known as crib death or cot death.

Earlier, the syndrome was called SIDUO, Sudden Infant Death of Unknown Origin, to indicate that the infant’s demise was sudden and unexplained. An infant who is found unconscious, is revived and hospitalized and later expires, should not be listed as SIDS; he was not dead when he was found. Similarly, a diagnosis of SIDS is inappropriate if the patient is found to have cerebral edema, hemorrhages, pneumonia, liver involvement or if he or she had fever, convulsions, vomiting or diarrhea before expiring Lastly, the infant must have been healthy and the death unexpected to fulfill the criteria. An infant with a multitude of health problems, who is exposed to extreme cold or is given a medication known to affect heart rate or rhythm and dies, should not be listed as a case of SIDS.

SIDS was infrequent before 1950. Its incidence in the United States rose to some 8,000 cases a year and is apparently lower now. The decrease has been attributed to the recommendation that babies be placed on their backs to sleep.

There have been numerous theories of crib death over the years. Extensive research is still on going. Several theories and causes, other than sleep position, have been proposed.

The following is a partial listing:

Medical / Scientific causes

  • Prematurity, low birth weight, broncho-pulmonary dysplasia
  • Respiratory and other viruses
  • Immune incompetence and susceptibility of the infant to infectious agents
  • Colonization by toxin-producing staphylococci.
  • Disturbances in chemo-receptor function, brain stem function, respiratory control and oxygenation, including sleep apnea.
  • Catecholamine neurotransmitters in the brain stem
  • Metabolic and enzyme defects.

Environmental causes

  • Winter months
  • Sleeping with parents
  • Soft bedding
  • Over heating: House too warm, baby over-dressed or over-wrapped
  • The use of phosphorus and antimony compounds as fire retardants in crib mattresses in certain countries and possible chemical reactions (sweat and fungi.)

Social causes

  • Mother younger than 20 years of age
  • Mother unmarried
  • Mother had late or no prenatal care
  • Mother smoked before, during, or after pregnancy

Two recent studies looked at social causes in more detail. The following quotes summarize the findings:

"Babies born to cohabiting couples faced a risk of SIDS that is almost identical to that of babies born to unmarried mothers (Relative Risks for cohabiting mothers, 6.20; for single mothers, 6.81)." Pediatrics (1997) Vol. 100.p. 835-840.

"Among factors associated with SIDS, illegitimacy increased as a risk factor since 1991. The SIDS odds ratio for infants born to unmarried mothers, relative to infants born to married mothers, increased from 1.4 before 1991 to 2.0 after 1991." (Pediatrics (2001) Vol. 139-p. 771-777.)

It is difficult to understand how a single social factor could be responsible for a sudden significant increase in the incidence of SIDS in this particular group of infants.

Although for years more SIDS deaths occurred in the winter months and were blamed on winter respiratory infections or overheating and overdressing, findings from a 12 year study from Ireland suggest that such timing has changed: 48.5% of SIDS occurred during the 6 colder months compared to 51.5% during the warmer six months (April to September inclusive)

In the (SIDS) Irish study, 10.9% of infants died in the first month of life.

The majority 59.4%, died between 2 & 4 months, 82.7% of infants died in the first six months and 2.9% died over the age of one.


Some parents who lost infants to SIDS believe that their infants’ sudden and unexpected demise was related to certain vaccinations that they had just received. The Center for Disease Control and Prevention (CDC), the central health authority in the Nation, has adamantly denied this possibility for decades. Several parents’ groups have endorsed the CDC position and have raised funds to support research.

The CDC Statement on SIDS and Vaccines

"The age at which infants begin their primary course of vaccinations (2-4 months) is also the peak age for the incidence of SIDS. The similar timing of these two events has led some people to believe that the events might be related. However, recent studies have concluded that vaccinations are not a risk factor for SIDS or sudden unexpected death in infants. The incidence of SIDS is declining in the US due to public education campaigns regarding infant sleeping position, reduced exposure of infants to cigarette smoke and fewer potentially hazardous sleeping environments. Recent reports and studies, combined with the decrease in SIDS rate despite the increase in vaccinations, support the conclusion that routine childhood vaccinations do not contribute to SIDS."

Researchers quoted by the vaccine authorities essentially claim that their conclusions are based on the fact that the incidence of SIDS after vaccination is not higher than that in the general population.


The March 12, 2003 IOM Report

"Vaccinations and Sudden Unexplained Death in Infancy"

The CDC and the National Institute of Allergy and Infectious Diseases (NIAID) requested and funded a study by the Institute of Medicine (IOM) on SIDS and vaccination. The IOM is a private, nonprofit institution that provides health policy advice under a Congressional Charter granted to the National Academy of Sciences.

Findings of IOM studies are summarized under five classifications

No evidence bearing on a causal relation.
The evidence is inadequate to accept or reject a causal relation.
The evidence favors rejection of a causal relation.
The evidence favors acceptance of a causal relation.
The evidence establishes a causal relation.

The following are quotes from the IOM study on vaccinations and SIDS:

  • Medical researchers have not reached consensus on the risk factors for SIDS or how it occurs, although current guidelines to place babies on their backs or sides to sleep are based on theories that the prone position may contribute to SIDS.
  • Further research could show that there are many causes of SIDS.
  • Another possible explanation, the "triple-risk" hypothesis, postulates that SIDS may occur through the interaction of an underlying biological vulnerability, a critical development period, and exposure to an outside trigger. It has been speculated that vaccination may act as such a trigger.

Nevertheless, the official study report contained the following statement as a summary of the findings:

"The evidence does not support a causal link
between sudden infant death syndrome (SIDS)
and either the diphtheria, tetanus, and
whole-cell pertussis (DTwP) vaccine or
exposure to multiple childhood vaccines."

Clearly "if medical researchers have not reached a consensus on the risk factors" and "further research could show that there are many causes for SIDS" then the second IOM classification "The evidence is inadequate to accept or reject a causal relation" is more justified than the first "No evidence bearing on a causal relation".

In much advertised and quoted statements to the media, the chairperson of the committee went further when she stated:

"Although the timing of infant vaccinations coincides with the period when SIDS is most likely to occur, parents should rest assured that the number and variety of childhood vaccines do not cause SIDS".

"We do not have the data that would definitively answer all questions about links between vaccines and SIDS and other forms of sudden, unexpected death in infancy. However, we believe that the data we do have, along with the increasing rarity of these kinds of infant deaths, make a review of the vaccine schedule unnecessary."

One would think that if we do not have all the answers, we should look for them carefully before deciding that a review is unnecessary. In any case, both statements by the Chairperson are not justified by the study findings:

  • "Medical researchers have not reached consensus on the risk factors for SIDS or how it occurs"
  • "Further research could show that there are many causes of SIDS".


"The Vaccine Adverse Event Reporting System is a cooperative program for vaccine safety of the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA). VAERS is a post-marketing safety surveillance program, collecting information about adverse events (possible side effects) that occur after the administration of US licensed vaccines.
This Web site provides a nationwide mechanism by which adverse events following immunization (AEFI) may be reported, analyzed and made available to the public. The VAERS Web site also provides a vehicle for disseminating vaccine safety-related information to parents/guardians, healthcare providers, vaccine manufacturers, state vaccine programs, and other constituencies."

Only 10% of vaccine adverse events are ever reported to VAERS, in spite of the efforts of the CDC and the vaccine immunization programs in the different states.

The vaccine authorities have always warned about misinterpretation of data and findings in VAERS reports. Their statement is clear.

When evaluating data from VAERS, it is important to note that for any reported event, no cause and effect relationship has been established. VAERS is interested in all potential associations between vaccines and adverse events. Therefore, VAERS collects data on any adverse event following vaccination, be it coincidental or truly caused by a vaccine. The report of an adverse event to VAERS is not documentation that a vaccine caused the event.

The purpose of this review is to examine the subject of SIDS and vaccines by reviewing reports to VAERS, from the start of the program in 1990 through the end of 2002.

One should be extremely cautious in drawing conclusions. The fact that an infant died of SIDS shortly after receiving a certain vaccine should not imply that he or she died because of the vaccine. Infants almost always receive more than one vaccine at a time. The same report/case will be listed with each of the vaccines administered to the infant. As an example, in the first case listed with DTAP (Diphtheria, tetanus, acellular pertussis vaccine) the infant also received a dose of HIB (Hemophilus influenzae B) vaccine and therefore that case will also be listed under HIB. The only exception is in the nursery and the first month of life when the first dose of hepatitis B vaccine is usually administered.


VAERS data search

Vaccines: DTAP, DTP, DTPH, HIB, HBHEPB, HEP, HEP (under age 1 month)
DTP: Diphtheria, Tetanus and whole cell Pertussis (sometimes referred to as DTwcP)
HBHEPB: HIB + Hepatitis B vaccine
HEP: Hepatitis B vaccine








All ages



All reports
















% Of total








SIDS cases








% Of total








% Of deaths








Table I
All reports: Number of reports filed with VAERS in which the vaccine was listed
Deaths: Number of reports of death for each vaccine
% Of total: The percentage of patients who died as compared to total reports for that vaccine.
SIDS cases: The number of reports for each vaccine where SIDS was listed as the cause of death
% Of total: The percentage of cases of SIDS per vaccine as compared to total reports
% Of deaths: The percentage of cases of SIDS compared to deaths for each vaccine

During the period reviewed, there was a gradual switch from DTP to DTAP. A reliable comparison of DTP and DTAP reports is impossible.

In fact, a reliable comparison of the data in the table above is also impossible, because several vaccines were often administered together. The only exception is the Hepatitis B vaccination in the newborn period.

Only the CDC and FDA have the needed information to prove or disprove the following suggestions from the above data:

  • DTAP may be a little better than DTP
  • The DTPH combination may be a little worse than either DTP or HIB
  • HIB alone may be a little worse than DTP and a little better than DTPH
  • The HBHEPB combination is somewhat worse than HIB and HEP (all)
  • Hepatitis B vaccination in the newborn period has generated proportionately more death reports and more SIDS reports than any other single vaccine or vaccine combination.

Historically, DTP has been the one vaccine most often suspected by parents, to be associated with SIDS. As previously stated, the CDC has denied such association quoting a multitude of studies intended to show that the incidence of SIDS was not any higher after DTP vaccination than it would have been expected in the general population. No recent studies on the subject are available.

Japan discontinued the use of DTP in 1975 and used DTAP exclusively since 1981.

In the United States, DTAP was licensed for infants in 1996.

It is not known whether the vaccine and health authorities have undertaken reviews of SIDS in close association with DTAP, HIB, Hepatitis B and combination vaccines. . Certainly none have been publicized.

This review will focus on SIDS reports to VAERS of infants who were younger than one month of age and who had received one dose of Hepatitis B vaccine.

Age: 0.0 to 0.0
Vaccine: HEP

Results: There were 32 reports of infant deaths.
  21 of the 32 deaths were listed as SIDS.
  6 of the 21 infants with SIDS died within 3 days of vaccination.
  Another infant died on the 4th day.
  Among the 21 infants diagnosed with SIDS, 13 (62%) were boys.





Lot Number












19 d.







11 d.







6 d.







2 m.







7 m.







15 d.







2 m.







6 m.







7 m.







17 d.







22 m.







23 m.







2 m.







9 m.







2 m.







8 m.







2 m.














9 m.







8 m.







28 d.

Table II


Parents who are told that their infants’ death is "unexplained" and doctors who have "diagnosed" SIDS are unlikely to report the case to VAERS as a vaccine adverse event. It is therefore certain that only a small number of cases is ever reported to VAERS.

New Hampshire

There is no reasonable explanation why 57% (12/21) of the above SIDS reports were from New Hampshire, a state with an estimated population of 1.3 million, when forty other states did not report a single case in that age group and with that particular vaccine, Texas and New York included. Two of the NH reports (108795 and 108796) were filed on the same day.

The fact that reports from New Hampshire were filed from 2 to 9 months after the infant’s demise would suggest that the large number of reports from New Hampshire was not simply due to a unique heightened awareness among parents and doctors. The case from Maryland was filed just 6 days after the infant’s demise, the one from Pennsylvania within 11 days and the one from California within 2 weeks.

It is unlikely that the "background" incidence of SIDS in New Hampshire is higher than that of the other 49 states combined. It would be interesting to know if the incidence of SIDS in infants under one month of age was just as high in New Hampshire before 1991, when the routine administration of hepatitis B vaccine in the newborn period was recommended.

Lot Numbers

Cases 91425, 97016 and 108796 received vaccines from lot 0165D.
There were 14 reports with that lot. The only deaths were the above cases from NH.

Two other infants from NH, cases 122713 and 123168, received vaccines from lot 2930A2. A 3-month old female infant from California (case164442) received a dose of HEP from the same lot a month after case 123618 and was found dead two days later. The cause of death was also listed as SIDS. This was that baby’s second dose of HEP. The baby received DTAP, HIB and IPV (Inactivated Polio Vaccine) on the same day.

Interesting Cases

Cases 51688, 59322, 83615, 100366, 118117 and 150249 will be discussed.

Case 51688: This female infant from Pennsylvania received a dose of HEP (lot 1116A2) on 3/29/93. Less than 48 hours later [at 5:00am on 3/31/93] she was brought to the local emergency room in full arrest

Findings: epistaxis (bleeding from the nose), heart arrest, fatty liver, petechiae on thymus, pericardium and pleura.

This infant had evidence of bleeding and fatty infiltration of the liver.

There were 65 reports to VAERS of bleeding with Hepatitis B vaccine. There were 719 reports listing liver problems.

There were 9 reports about HEP lot number 1116A2 with 3 deaths diagnosed as SIDS. The other two are cases 53486 and 55368.

Case 53486: This 2-month old female infant from Oregon received DTP, HIB, OPV (Oral Polio Vaccine) and Hepatitis B vaccine on 5/11/93. She died of SIDS on 5/14/93. The VAERS report was filed three weeks later.

Case 55368: A 2-month old male infant, also from Oregon who was born 5-6 weeks prematurely; He received his first dose of DTP, HIB, OPV and Hepatitis B vaccines on 6/24/93. He died 23 days later. HEM is listed under symptom (possibly hemorrhage). An autopsy was performed and "confirmed" SIDS, yet the report was filed one month later.

In another report (53601), a 3-month old male from DC received DTP, HIB, OPV and HEP from the same lot on 4/6/1993. On 4/11, the baby became "stuporous" and was rushed to the ER. He remained in the hospital several days. No further information is available.

Case 59322: This female infant from South Carolina received a Hepatitis B vaccination (lot 0942W) on 11/30/93 and died suddenly on 12/10/93. Although an autopsy was not mentioned, it appears that one was done as the infant apparently had a "cyst, edema, brain hemorrhage and lung disease". In spite of these findings, SIDS was listed as the cause of death. The report was filed on 2/2/94.

There were 33 reports to VAERS with lot number 0942W. One other infant, a 2-month old male from IOWA who also received DTP, HIB and OPV on 7/1/94 also died.

Case 70603: This female infant from New Hampshire received her first Hepatitis B vaccine (lot 1547W) on 6/24/94. She died 19 days later. At the time of death, the infant was receiving ampicillin. Antibiotic eye drops were also being used. Gastroesophageal reflux (GER) was listed as a pre-existing condition. It is reasonable to assume that the GER and whatever infection was being treated with ampicillin were not present when the infant was vaccinated but developed after vaccination. Though there is no mention of an autopsy, the cause of death was listed as SIDS. The report was filed 6 months later.

There were 32 reports with Hepatitis B Vaccine, lot 1547W. 14 children were taken to an ER and 4 were hospitalized. Three infants died.

The two other deaths were:

Case 66741: A 2-month old male, also from NH, who was given DTP, HIB and OPV with the hepatitis B vaccine on 8/29/94; He was irritable that day but "was fine, smiling and acted normal with good eating" the next morning. "He was put down for a nap and died 15-20 minutes later. Autopsy: consistent with SIDS". The VAERS report was filed 3 weeks later.

Case 69993: A 2-month old male from Ohio, who received DTP, HIB, OPV and Hepatitis B vaccine (1547W) on 12/1/94 and was apparently well for the following six days. He died on the 7th day post-vaccination (12/8/94). An autopsy was performed. The cause of death was listed as SIDS. The VAERS report was filed less than a month later.

Case 83615: This male infant from California was vaccinated on 2/26/96. The vaccine he received was from lot # 1196B. The infant developed a fever to 102 on the same day and again on 2/27 and 2/28. Blood culture grew a contaminant on 2/26 but was negative on 2/27. The report mentions "Sudden death" on 2/28/96 at 2:00pm. The report to VAERS was filed two weeks later.

Was this death really "Sudden"? Fever for 48 hours is not a symptom of SIDS.

Interestingly, case 83659, also an infant from California who was 1 week old, received a dose of hepatitis B vaccine from the same lot (1196B) on the same day and also developed a fever a few hours after vaccination. He expired the following day. Blood culture was negative. The cause of death was listed as "febrile illness" on the VAERS report.

There were 34 reports to VAERS in all with lot # 1196B and 12 patients were taken to an ER. In many cases, the infant or child had received other vaccines at the same time.

Case 100366: This male infant from Mississippi was vaccinated 7/6/97. At 5:30:am the following morning (20 hours after vaccination) he was found apneic and pulseless in his crib. The report states that there was apnea, pulmonary edema, encephalopathy, cardiac arrest, myocardial infarction and cerebral ischemia. The report goes on to say: "No evidence of severe hypoxic brain injury; autopsy without evidence of anomalies." The vaccine lot number was not listed.

This infant died 20 hours after receiving a dose of hepatitis B vaccine.
Encephalopathy is not a symptom of SIDS; few hours after a vaccination, it strongly suggests a vaccine reaction.

Case 118117: This male infant from West Virginia was vaccinated on 5/29/98 (lot #2612A2). Symptoms listed: Sweating, irritable, crying, swollen injection site, hard to console. Infant was put to sleep in parents’ bed at 2:00am, and was found dead at 4:00am, 16 hours after vaccination. Autopsy report: SIDS.

This infant had symptoms suggesting a vaccine reaction and expired 16 hours after vaccination. Reporting the case to VAERS appears fully justified.
There were 11 reports of ER visits after vaccination with HEP lot 2612A2.

Two of those reports are

Case 125097. A 5-year old boy from Louisiana, who received a dose from the same hepatitis B vaccine lot (and no other vaccine) on 7/20/1998, had a grand mal seizure 2 days later and 37 more seizures within 2 weeks. He now has epilepsy and takes Tegretol.

Case 114285: A 2-month old male infant from Georgia who received DTAP, HIB and OPV in addition to the dose of hepatitis B vaccine (lot 2612A2) at 9:00 am on 9/3/1998 and was found limp and blue by parents at noon.

Case 150249: This female from New Jersey was 7 days old when she was vaccinated on 2/28/2000. The vaccine lot number was not listed. On 3/3/2000, the child expired. The baby had no congenital anomalies. "Autopsy revealed cerebral edema and pulmonary edema. Cause of death determined to be SIDS."

Was this a sudden and unexplained death?

Were the cerebral and pulmonary edema found on autopsy terminal events of a SIDS death or was the death related to the vaccine administered 3-4 days earlier?

There were 5 reports to VAERS with cerebral edema and 9 reports with pulmonary edema in patients who had received a hepatitis B vaccination. Many had also received other vaccines at the same time.


Meaningful inferences are impossible because of the serious underreporting to VAERS.

It appears that SIDS is the diagnosis in the majority of deaths reported following DTAP, DTP, DTPH, HBHEPB, HIB, and Hepatitis B vaccination, the only vaccines reviewed.

It is likely that only some cases of SIDS associated with neonatal hepatitis B vaccination in New Hampshire have been reported to VAERS. Even if there were only 12 cases in the State in all in ten years of VAERS reports, then the number of cases in the rest of the Nation should have exceeded 2,500. There were only 9 reports filed.

In 15 of the 21 reports, there is no mention or indication of an autopsy. It is possible that autopsies were performed. By definition, (see paragraph 1), an autopsy is required to rule out other causes for the baby’s demise.

In many reports, the case definition of SIDS is not being uniformly applied.

There were several cases, mostly in earlier years, where the diagnosis of SIDS after an autopsy, was neither supported by the symptoms nor by the pathological findings.

This review shows that some informed physicians and parents felt that, in spite of a diagnosis of Sudden Infant Death Syndrome, the demise of the infant was related to vaccination and reported the case to VAERS as an adverse event.

The New Hampshire Department of Health should review the situation. Parents, nationwide, would certainly appreciate the information.

New Hampshire physicians deserve credit for their effort at reporting adverse events.

The CDC and the FDA are still unable, in spite of all their efforts, to convince physicians and families to report all adverse events to VAERS.

Combination vaccines are probably as effective as their components. Some experts, the IOM included, have asserted that they do not cause more reactions and are just as safe as their components. This limited review suggests otherwise.

Recombinant Hepatitis B vaccination seems to have caused an inordinate number of adverse reactions.

Neonatal vaccination with Recombinant HEP was initiated in 1991. Young single mothers are less likely to question vaccinations and usually try to have the recommended immunizations administered to their infants and children on schedule, so as not to be accused of child neglect. The possibility that this is the reason for the increase in the incidence of SIDS after 1991 in that particular group of children should be considered.



A serious review of SIDS cases in the first month of life and their timing relative to Hepatitis B vaccination should be undertaken in every state.

A committee of the Institute Of Medicine should revisit the whole subject of Sudden Infant Death occurring shortly after pediatric vaccinations, whether the vaccines were administered alone, with others or as combinations. This time, serious analysis of VAERS reports should be an integral part of the investigation.

Primary physicians, ER teams and medical examiners should consider vaccinations shortly before an unexplained death in their differential diagnosis before certifying that the cause of death is "Sudden Infant Death Syndrome".