At
a glance: In 1998 a researcher presented a theory suggesting
that vaccines, depending on when they are administered, may
increase or decrease the risk that certain people may develop
type 1 diabetes, previously called juvenile onset or insulin-dependent
diabetes mellitus (IDDM).
The cause of type 1 diabetes is not
completely understood but it is believed that genetic and environmental
factors may be involved. Vaccinations have been studied as a
possible environmental risk factor and the scientific studies
conducted have found no relationship between immunizations and
type 1 diabetes.
On this page:
- What is diabetes?
- Do vaccines cause
diabetes?
- What about evidence
that suggests vaccines cause diabetes?
- What is being
done to monitor the safety of vaccines?
Related pages:
What is diabetes?
Most of the
food we eat is turned into glucose, or sugar, for our bodies to
use for energy. The pancreas, an organ that lies near the stomach,
makes a hormone called insulin to help glucose get into the cells
of our bodies. If a person has diabetes, their body can’t
make enough insulin or can’t use its own insulin as well
as it should. This causes sugar to build up in the blood. Diabetes
is classified into two main types:
-
Type 1
— Previously known as insulin-dependent diabetes
mellitus (IDDM) or juvenile diabetes. In Type 1 diabetes,
which accounts for 5-10% of all diabetes cases, the body does
not produce insulin. Risk factors are less well defined for
type 1 diabetes than for type 2 diabetes, but genetic, environmental
and autoimmune factors are involved in the development of
this type of diabetes.
-
Type 2
— Previously known as non-insulin
dependent diabetes mellitus (NIDDM) or adult-onset diabetes.
In Type 2 diabetes, which accounts for 90-95% of all cases
of diabetes, either the body does not produce enough insulin
or the insulin does not work. Risk factors for type 2 diabetes
include older age, obesity, family history, impaired glucose
tolerance, physical inactivity and race/ethnicity (African
Americans, Hispanic/Latino Americans, Native Americans, and
some Asian Americans and Pacific Islanders are at increased
risk).
In
discussion below, "diabetes" refers to type 1.
[Top]
Do
vaccines cause
diabetes?
No. Carefully
performed scientific studies show that vaccines do not cause diabetes
or increase a person’s risk of developing diabetes (DeStefano
2001, EURODIAB Substudy 2 Study Group 2000, Karvonen 1999, Heijbel
1997, Parent 1997, Dahlquist 1995, Hyoty 1993, Blom 1991). In
2002, the Institute of Medicine reviewed the existing studies
and released a report
concluding that the scientific evidence favors rejection of the
theory that immunizations cause diabetes. Furthermore, DeStefano
and colleagues (2001) recently conducted the first study looking
at whether the timing of childhood vaccinations, particularly
of Hepatitis B, is related to the risk of a child getting diabetes.
This study, which examined data from 1,020 children in the U.S.,
did not show an association between any of the recommended childhood
vaccines and diabetes, regardless of when the vaccines were given.
Other studies also provide evidence that vaccination does not
cause diabetes:
- A European study that examined
900 diabetic and 2,302 non-diabetic children found a slight
relationship between infections during early infancy and risk
of developing diabetes. However, the researchers did not find
a relationship between any of the common childhood
infections or childhood vaccines and diabetes in children.
(EURODIAB Substudy 2 Study Group 2000)
- A study conducted in Sweden
looked at 1,267 diabetic children in two groups: a group of
children that were born during the time that pertussis vaccination
was used and a group of children that were born after pertussis
vaccine had been removed from the immunization schedule. The
researchers found no difference in the incidence rate of diabetes
between the children born before and the children born after
1979, when pertussis was excluded from routine immunizations
in Sweden. (Heijbel 1997)
- The
results from a study that examined 339 diabetic and 528 non-diabetic
Swedish children showed that children that received measles
vaccine were slightly protected against getting diabetes.
The study showed no relationship, positive or negative, between
tuberculosis, smallpox, tetanus, whooping cough, rubella and
mumps vaccines and diabetes in children. (Blom 1991)
[Top]
What about
evidence that suggests that vaccines cause diabetes?
The only evidence suggesting
a relationship between vaccination and diabetes comes from Dr.
John B. Classen (Classen 1996; Classen and Classen 1997; Classen
and Classen 2002). He has suggested that certain vaccines if
given at birth may decrease the occurrence of diabetes, whereas
if initial vaccination is performed after 2 months of age the
occurrence of diabetes increases. Dr. Classen's studies have
a number of limitations and have not been verified by other
researchers.
- This theory is based on results
from experiments in laboratory animals, as well as comparisons
of the rates of diabetes between countries with different
immunization schedules (Classen, 1996; Classen & Classen
1997). Applying findings from laboratory animals to humans
is fraught with uncertainty. Findings that are noted in animals
cannot be directly applied to people because of the large
biological differences. In addition, many of the animal experiments
involved anthrax vaccine, which is not used in infants and
children.
- Comparison of diabetes rates
between countries provides weak evidence because many factors,
including vaccination schedules, may differ by country. For
instance, comparisons between countries included vaccines
that are infrequently used in the U.S. (BCG) or are no longer
used (smallpox). Furthermore, factors such as genetic predisposition
and a number of possible environmental exposures unrelated
to vaccines, may influence the development of diabetes in
different countries.
Dr. Classen also performed an
analysis of data from a large study conducted in Finland of
Haemophilus influenzae type B (Hib) vaccine. Over 100,000
children were randomly assigned to receive either 4 doses of
vaccine starting at 3 months of age or a single dose at 24 months.
Over about a 10-year follow up period, 205 children in the multiple
dose group developed diabetes compared with 185 in the single
dose group.
- These results are inconclusive
because the exact number of children in each group is not
known and the noted differences may not be statistically significant
(that is, they could be due to "chance").
- The results from a similar
study using the same data from Finland were not the same as
Dr. Classen’s results (Karvonen et al. 1999). This study
was similar to Dr. Classen’s study except that it compared
children in 3 (rather than 2) different groups: 1) children
that were born before Hib vaccination was recommended (and
therefore did not receive the shot as part of their routine
immunizations),
2) children that began receiving Hib vaccine at 3 months of
age, and 3) children that
received a single dose of Hib at 24 months. This study did
not find a difference in diabetes risk between any of the
3 groups of children.
Dr.
Classen recently performed another analysis using the same data
from the group of children in Finland (Classen and Classen 2002).
In this study Dr. Classen suggests that by the age of 7 years
old a greater number of diabetes cases occurred in Finnish children
that had received the Hib vaccine than in children that had
not received the vaccine.
- In order for an association
between Hib vaccination and diabetes to be confirmed, the
results would have to be replicated in several other scientific
studies. No other studies, not even one using the exact same
data from the children in Finland (Karvonen 1999), have found
a relationship between Hib vaccine and an increase in diabetes
(DeStefano 2001, EURODIAB Substudy 2 Study Group 2000).
- It appears that Dr. Classen
may have conducted his statistical analysis after seeing the
results and noting that the largest difference was apparent
by 7 years. The validity of this type of 'post-hoc' statistical
testing, however, is highly questionable. When the full 10
years of follow-up was evaluated the differences were not
statistically significant, which is also what was found by
Karvonen and colleagues.
[Top]
What is
being done to monitor the safety of vaccines?
To assure the safety of vaccines, The Centers for Disease Control
and Prevention (CDC), the Food and Drug Administration (FDA),
the National Institutes of Health (NIH), and other Federal agencies
routinely monitor vaccine safety and conduct research to examine
any new evidence that would suggest possible problems with the
safety of vaccines. The CDC's Vaccine Safety Datalink (VSD) project
links the immunization and medical records on members of seven
HMOs, totaling 2.5% of the US population for various vaccine safety
studies. The VSD project is a powerful and cost-effective tool
for the on-going evaluation of vaccine safety. The Vaccine Adverse
Event Reporting System, or VAERS, was designed to give health
care workers and others a place to report possible problems following
vaccination. VAERS helps the FDA and CDC to continuously monitor
vaccine safety. To request a VAERS form or to get more information
about VAERS, please call 1-800-822-7967 or go to the VAERS website
http://www.vaers.org.
For
more information about vaccines and vaccinations, contact
CDC's National Immunization Information Hotline:
English: 1-800-232-2522
Spanish: 1-800-232-0233
Or,
visit the CDC's National Immunization Program's web site: http://www.cdc.gov/nip
[Top]
References
- Blom L, Nystrom L, Dahlquist
G. The Swedish childhood diabetes study: Vaccinations and infections
as risk determinants for diabetes in childhood. Diabetologia 1991;34(3):176-81.
- Classen DC, Classen JB. The timing
of pediatric immunization and the risk of insulin-dependent diabetes
mellitus. Infectious Diseases in Clinical Practice 1997;6:449-454.
- Classen JB. The timing of immunization
affects the development of diabetes in rodents. Autoimmunity 1996;24:137-145.
- Classen JB, Classen DC. Clustering
of cases of insulin dependent diabetes (IDDM) occurring three
years after Haemophilus Influenza B (HiB) immunization support
causal relationship between immunization and IDDM. Autoimmunity
2002; 35(4):247-353.
- Dahlquist G, Gothefors L. The
cumulative incidence of childhood diabetes mellitus in Sweden
unaffected by BCG-vaccination. Diabetologia 1995;38:873-874.
- DeStefano F, Mullooly JP, Okoro
CA, Chen RT, Marcy SM, Ward JI, Vadheim CM, Black SB, Shinefield
HR, Davis RL, Bohlke K. Childhood vaccinations, vaccination timing,
and risk of type 1 diabetes mellitus. Pediatrics 2001;108(6):E112.
-
EURODIAB Substudy 2 Study Group. Infections and vaccinations as
risk factors for childhood type 1 (insulin-dependent) diabetes
mellitus: a multicentre case-control investigation. Diabetologia
2000;43(1):47-53.
- Heijbel H, Chen RT, Dahlquist
G. Cumulative incidence of childhood-onset IDDM is unaffected
by pertussis immunization. Diabetes Care 1997;20:173-175.
- Hyoty H, Hiltunen M, Reunanen
A, et al. Decline of mumps antibodies in Type 1 (insulin-dependent)
diabetic children and a plateau in the rising incidence of type
1 diabetes after introduction of the mumps-measles-rubella vaccine
in Finland. Diabetologia 1993;36:1303-1308.
- Institute
of Medicine. Stratton K, Wilson CB, McCormick MC, eds. Multiple
immunizations and immune dysfunction. National Academy Press,
Washington, DC. 2002. http://www.nap.edu/books/0309083281/html/
-
Karvonen
M, Cepaitis Z, Tuomilehto J. Association between type 1 diabetes
and Haemophilus influenzae type b vaccination: birth cohort study.
British Medical Journal 1999;318(7192):1169-1172.
- Parent M, Fritschi L, Siemiatycki
J, Colle E, Menzies R. Bacille Calmette-Guerin vaccination and
incidence of IDDM in Montreal, Canada. Diabetes Care 1997;20:767-772.
From the
National
Immunization Program of the Centers for Disease Control and Prevention
September 24, 2002
http://www.cdc.gov/nip/vacsafe/concerns/Diabetes/q&a.htm
Also see
diabetes and vaccines — fact sheet
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