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What Would Happen
If We Stopped Vaccinations?
In the U.S., vaccination programs have eliminated or significantly
reduced many vaccine-preventable diseases. However, these diseases
still exist and can once again become common—and deadly—if
vaccination coverage does not continue at high levels.
Figures and statistics updated August 2003 |
| Measles | Type
b (Hib) Meningitis | Hepatitis
B Pertussis (whooping cough)
| Rubella (german measles)
Varicella (chickenpox) |
Diphtheria | Tetanus
(lockjaw) | Mumps
In the U.S., vaccines have reduced or eliminated many infectious
diseases that once routinely killed or harmed many infants,
children, and adults. However, the viruses and bacteria that
cause vaccine-preventable disease and death still exist and
can be passed on to people who are not protected by vaccines.
Vaccine-preventable diseases have many social and economic
costs: sick children miss school and can cause parents to
lose time from work. These diseases also result in doctor's
visits, hospitalizations, and even premature deaths.
Polio virus causes acute paralysis
that can lead to permanent physical disability and even death. Before polio
vaccine was available, 13,000 to 20,000 cases of paralytic polio were
reported each year in the United States.
These annual epidemics of polio often left thousands of victims--mostly
children--in braces, crutches, wheelchairs, and iron lungs. The effects were
Development of polio vaccines
and implementation of polio immunization
programs have eliminated paralytic polio caused
by wild polio viruses in the U.S. and the entire Western
In 1999, as a result of global
immunization efforts to eradicate the disease, there were about 2,883
documented cases of polio in the world. In 1994, wild polio virus was
imported to Canada from India, but high vaccination levels prevented it from
spreading in the population.
Before measles immunization was
available, nearly everyone in the U.S. got measles. An average
of 450 measles-associated deaths were reported each year between
1953 and 1963.
In the U.S., up to 20 percent
of persons with measles are hospitalized. Seventeen percent
of measles cases have had one or more complications, such as ear
infections, pneumonia, or diarrhea. Pneumonia is present in about
six percent of cases and accounts for most of the measles deaths.
Although less common, some persons with measles develop encephalitis
(swelling of the lining of the brain), resulting in brain damage.
As many as three of every 1,000
persons with measles will die in the U.S. In the developing world,
the rate is much higher, with death occurring in about one of every
100 persons with measles.
Measles is one of the most infectious
diseases in the world and is frequently imported into the U.S. In
the period 1997-2000, most cases were associated with international
visitors or U.S. residents who were exposed to the measles virus
while traveling abroad. More than 90 percent of people who are not
immune will get measles if they are exposed to the virus.
According to the World Health Organization
(WHO), nearly 900,000 measles-related deaths occurred among persons
in developing countries in 1999. In populations that are not immune
to measles, measles spreads rapidly. If vaccinations were stopped,
each year about 2.7 million measles deaths worldwide could be expected.
In the U.S., widespread use of
measles vaccine has led to a greater than 99 percent reduction in measles compared
with the pre-vaccine era. If we stopped immunization, measles would increase
to pre-vaccine levels.
Before Hib vaccine became available,
Hib was the most common cause of bacterial meningitis in U.S. infants
and children. Before the vaccine was developed, there were approximately
20,000 invasive Hib cases annually. Approximately two-thirds of
the 20,000 cases were meningitis, and one-third were other life-threatening
invasive Hib diseases such as bacteria in the blood, pneumonia,
or inflammation of the epiglottis. About one of every 200 U.S. children
under 5 years of age got an invasive Hib disease. Hib meningitis
once killed 600 children each year and left many survivors with
deafness, seizures, or mental retardation.
Since introduction of conjugate Hib
vaccine in December 1987, the incidence of Hib has declined by 98 percent.
From 1994-1998, fewer than 10 fatal cases of invasive Hib disease were
reported each year.
This preventable disease was a
common, devastating illness as recently as 1990; now, most pediatricians
just finishing training have never seen a case. If we were to stop
immunization, we would likely soon return to the pre-vaccine numbers of
invasive Hib disease cases and deaths.
Since the early 1980s, reported pertussis
cases have been increasing, with peaks every 3-4 years; however,
the number of reported cases remains much lower than levels seen
in the pre-vaccine era. Compared with pertussis cases in other age
groups, infants who are 6 months old or younger with pertussis experience
the highest rate of hospitalization, pneumonia, seizures, Encephalopathy
(a degenerative disease of the brain) and death. From 1990 to 1996,
57 persons died from pertussis; 49 of these were less than six months
Before pertussis immunizations were
available, nearly all children developed whooping cough. In the
U.S., prior to pertussis immunization, between 150,000 and 260,000
cases of pertussis were reported each year, with up to 9,000 pertussis-related
Pertussis can be a severe
illness, resulting in prolonged coughing spells that can
last for many weeks. These spells can make it difficult for a child
to eat, drink, and breathe. Because vomiting often occurs after
a coughing spell, infants may lose weight and become dehydrated.
In infants, it can also cause pneumonia and lead to brain
damage, seizures, and mental retardation.
The newer pertussis vaccine (acellular
or DTaP) that has been available for use in the United States since
1991 and has been recommended for exclusive use since 1998. These
vaccines are effective and associated with fewer mild and moderate
adverse reactions when compared with the older (whole-cell DTP)
During the 1970s, widespread concerns
about the safety of the older pertussis vaccine led to a rapid fall in
immunization levels in the United Kingdom. More than 100,000 cases and 36
deaths due to pertussis were reported during an epidemic in the mid 1970s.
In Japan, pertussis vaccination coverage fell from 80 percent in 1974 to 20
percent in 1979. An epidemic occurred in 1979, resulted in more than 13,000
cases and 41 deaths.
Pertussis cases occur throughout the
world. If we stopped pertussis immunizations in the U.S., we would
experience a massive resurgence of pertussis disease. A recent study*
found that, in eight countries where immunization coverage was reduced,
incidence rates of pertussis surged to 10 to 100 times the rates in
countries where vaccination rates were sustained.
*Reference for study: Gangarosa EJ, et al.
Impact of anti-vaccine movements on pertussis control: the untold story.
While rubella is usually mild in
children and adults, up to 90 percent of infants born to mothers
infected with rubella during the first trimester of pregnancy will
develop congenital rubella syndrome (CRS), resulting in
heart defects, cataracts, mental retardation, and deafness.
In 1964-1965, before rubella
immunization was used routinely in the U.S., there was an epidemic of
rubella that resulted in an estimated 20,000 infants born with CRS, with
2,100 neonatal deaths and 11,250 miscarriages. Of the 20,000 infants born
with CRS, 11,600 were deaf, 3,580 were blind, and 1,800 were mentally
Due to the widespread use of rubella
vaccine, only six CRS cases were provisionally reported in the U.S. in 2000.
Because many developing countries do not
include rubella in the childhood immunization schedule, many of these cases
occurred in foreign-born adults. Since 1996, greater
than 50 percent of the reported rubella cases have been among adults. Since
1999, there have been 40 pregnant women infected with rubella.
If we stopped rubella immunization,
immunity to rubella would decline and rubella would once again return,
resulting in pregnant women becoming infected with rubella and then
giving birth to infants with CRS.
Chickenpox is always present in
the community and is highly contagious. Prior to the licensing
of chickenpox vaccine in 1995, almost all persons in the U.S. had
suffered from chickenpox by adulthood. An estimated 4 million cases
of chickenpox occurred annually, resulting in 11,000 hospitalizations
and 100 deaths.
Chickenpox is usually mild, but may
be severe in some infants, adolescents, and adults. Some people
who get chickenpox have also suffered from complications such as
secondary bacterial infections, loss of fluids (dehydration),
pneumonia, and central nervous system involvement. In addition,
only persons who have had chickenpox in the past can get shingles,
a painful inflammation of the nerves. About 500,000
cases of shingles occur each year when inactivated chickenpox virus
is activated in people who have had chickenpox in the past.
Vaccine coverage among children 19-35
months was 80 percent in 2002.
More than 2 billion persons worldwide
have been infected with the hepatitis B virus at some time in their
lives. Of these, 350 million
are life-long carriers of the disease and can transmit the virus
to others. One million of these people die each year from liver
disease and liver cancer.
National studies have shown that about 12.5
million Americans have been infected with
hepatitis B virus at some point in their lifetime. One and one quarter
million Americans are estimated to have chronic (long-lasting) infection, of
whom 20 percent to 30 percent acquired their infection in childhood. Chronic
hepatitis B virus infection increases a person's risk for chronic liver
disease, cirrhosis, and liver cancer. About 5,000 persons will die each year
from hepatitis B-related liver disease resulting in over $700 million
medical and work loss costs.
The number of new infections per year has
declined from an average of 450,000 in the 1980s to about 80,000 in 1999.
The greatest decline has occurred among children and adolescents due to
routine hepatitis B vaccination.
Infants and children who become
infected with hepatitis B virus are at highest risk of developing lifelong
infection, which often leads to death from liver disease (cirrhosis) and
liver cancer. Approximately 25 percent of children who become infected with
life-long hepatitis B virus would be expected to die of related liver
disease as adults.
CDC estimates that one-third of the
life-long hepatitis B virus infections in the United States resulted from
infections occurring in infants and young children. About 16,000 - 20,000
hepatitis B antigen infected women give birth each year in the United
States. It is estimated that 12,000 children born to hepatitis B virus
infected mothers were infected each year before implementation of infant
immunization programs. In addition, approximately 33,000 children (10 years
of age and younger) of mothers who are not infected with hepatitis B virus
were infected each year before routine recommendation of childhood hepatitis B vaccination.
Diphtheria is a serious disease
caused by a bacteria. This germ produces a poisonous substance or toxin
which frequently causes heart and
nerve problems. The death rate is 5 percent to 10 percent, with higher death rates (up to
20 percent) in the very young and the elderly.
In the 1920's, diphtheria was a major
cause of illness and death for children in the U.S. In 1921, a total
of 206,000 cases and 15,520 deaths were reported. With vaccine development
in 1923, new cases of diphtheria began to fall in the U.S., until
in 2001 only two cases were reported.
Although diphtheria is rare in the
U.S., it appears that the bacteria continues to get passed among
people. In 1996, 10 isolates of the bacteria were obtained from
persons in an American Indian community in South Dakota, none of
whom had classic diphtheria disease. There has been one death reported
in 2000 from clinical diphtheria caused by a related bacteria.
There are high rates of susceptibility
among adults. Screening tests conducted since 1977 have shown that
41 percent to 84 percent of adults 60 and over lack protective levels
of circulating antitoxin against diphtheria.
Although diphtheria is rare in the U.S.,
it is still a threat. Diphtheria is common in other parts of the world and with
the increase in international travel, diphtheria
and other infectious diseases are only a plane ride away.
If we stopped immunization, the U.S. might experience a situation similar to
the Newly Independent States of the former Soviet Union.
With the breakdown of the public health services in this area, diphtheria
epidemics began in 1990, fueled primarily by persons who were not properly
From 1990-1999, more than 150,000 cases and 5,000 deaths were reported.
Tetanus is a severe, often fatal
disease. The bacteria that
cause tetanus are widely distributed in soil and street dust, are
found in the waste of many animals, and are very resistant to heat
and germ-killing cleaners. From
1922-1926, there were an estimated 1,314 cases of tetanus per year
in the U.S. In the late 1940's, the tetanus vaccine was introduced,
and tetanus became a disease that was officially counted and tracked
by public health officials. In 2000, only 41 cases of tetanus were
reported in the U.S.
People who get tetanus suffer from
stiffness and spasms of the muscles. The
larynx (throat) can close causing breathing and eating difficulties,
muscles spasms can cause fractures (breaks) of the spine and long
bones, and some people go into a coma, and die. Approximately
20 percent of reported cases end in death.
Tetanus in the U.S. is primarily a
disease of adults, but unvaccinated children and infants of unvaccinated
mothers are also at risk for tetanus and neonatal tetanus, respectively. From 1995-1997,
33 percent of reported cases of tetanus occurred
among persons 60 years of age or older and 60 percent occurred in patients
greater than 40 years
of age. The National Health Interview Survey found that in
1995, only 36 percent of adults 65 or older had received a tetanus vaccination
during the preceding 10 years.
in newborn infants continues to be a huge problem. Every year tetanus
kills 300,000 newborns and 30,000 birth mothers who were not properly
vaccinated. Even though the number of reported cases is
low, an increased number of tetanus cases in younger persons has
been observed recently in the U.S. among intravenous drug users,
particularly heroin users.
Tetanus is infectious, but not contagious,
so unlike other vaccine-preventable diseases, immunization by members
of the community will not protect others from the disease. Because
tetanus bacteria are widespread in the environment, tetanus can
only be prevented by immunization. If vaccination against tetanus
were stopped, persons of all ages in the U.S. would be susceptible
to this serious disease.
Before the mumps vaccine was introduced,
mumps was a major cause of deafness in children, occurring
in approximately 1 in 20,000 reported cases. Mumps
is usually a mild viral disease. However, rare conditions such as
swelling of the brain, nerves and spinal cord can lead to serious
side effects such as paralysis, seizures, and fluid in the brain.
Serious side effects of mumps are more common
among adults than children. Swelling of the testes is the most common
side effect in males past the age of puberty, occurring in up to 20
percent to 50 percent of men who contract mumps.
An increase in miscarriages has been found among women who develop
mumps during the first trimester of pregnancy.
An estimated 212,000 cases of mumps occurred
in the U.S. in 1964. After vaccine licensure in 1967, reports of
mumps decreased rapidly. In 1986 and 1987, there was a resurgence
of mumps with 12,848 cases reported in 1987. Since 1989, the incidence
of mumps has declined, with 266 reported cases in 2001. This recent
decrease is probably due to the fact that children have received
a second dose of mumps vaccine (part of the two-dose schedule for
measles, mumps, rubella or MMR) and the eventual development of
immunity in those who did not gain protection after the first mumps
If we were to stop vaccination against
mumps, we could expect the number of cases to climb back to pre-vaccine
levels, since mumps is easily spread among unvaccinated persons.