What is the Vaccine Adverse Events Reporting System (VAERS)?

The Vaccine Adverse Events Reporting System (VAERS) is one of several vaccine monitoring programs

that are used to monitor vaccine safety in the United States. The U.S. Food and Drug Administration

(FDA) and the Centers for Disease Control and Prevention (CDC) established VAERS in 1990 to record

and track reactions or adverse events that occur after a vaccine is given to patients.

Anyone can file a VAERS report if they think they or someone they know has had a reaction to a

vaccine. VAERS receives reports from health care professionals, parents, and patients.

Doctors and other medical research experts from FDA and CDC analyze the VAERS reports to monitor

vaccine safety. Potential safety problems that are detected during regular reviews of VAERS reports are

considered to be only a "signal" of a possible safety problem. When the VAERS data "signals" a

potential safety problem, the vaccine is thoroughly investigated through other research methods. This

is because adverse events reports to VAERS are self-reported and not routinely verified before being

entered into the system, thus great caution must be used in interpreting patterns found in the data.

Verification studies have shown that most adverse events reported in the VAERS database are not

actually caused by an immunization. Rather, the "adverse events" that are shown to be unrelated to

an immunization were the result of some other cause, such as a naturally occurring illness.

The rotavirus vaccine is a recent example of how VAERS works. Analysis of VAERS data in 1999

identified that 15 cases of a rare but serious bowel obstruction were reported in association with

the rotavirus vaccine (after approximately 1.5 million doses of the newly licensed vaccine had been

given to patients). Medical experts are now conducting further studies to better understand the

relationship between the bowel obstructions and the vaccine. In the meanwhile, the vaccine has

been withdrawn from use in the United States.

The VAERS telephone number is 1-800-822-7967; the Web site is www.fda.gov/cber/vaers; and the

email address is vaers@cber.fda.gov.

Are there "hot lots" of vaccines that have been associated with more adverse events than

others have? Should parents find the numbers of these lots and make sure their children don't

receive vaccines from them?

The answer to both of these questions is no. Manufacturers produce and distribute vaccines in

quantities known as "lots." Lot sizes vary widely between different types of vaccines and different

manufacturers. Samples of each lot are sent to the FDA for tests of safety, potency, and purity

VAERS data can be used to monitor how many adverse events have been reported for each vaccine

"lot" approved for use. However, because vaccine lots are not all of the same size, nor distributed

and used at the same rate, differences in the numbers of adverse events reported must be

interpreted with great caution. Some people have misinterpreted the difference between the

number of adverse events in some lots versus other lots as meaning that some lots, i.e. "hot lots,"

are more dangerous than others.

The American Academy of Pediatrics, the Centers for

Disease Control and Prevention, and the American Academy of Family Physicians recommend that

doctors avoid immunizing a person who has had an anaphylactic reaction to a component of a

vaccine. However, people who have had less serious reactions to a vaccine might choose to be

vaccinated to avoid the risk of illness or death from vaccine-preventable diseases.

Also, children with a personal or family history of seizures may be at greater risk of having seizures

However, this vaccine

is no longer recommended for use in the United States. The newer DTaP vaccine (which includes the

greatly purified acellular pertussis vaccine [aP] as a component) which is now used is far less likely

to cause seizures in any children. DTaP is safe and recommended even for children with a family

Source: The National Network for Immunization Information (www.immunizationinfo.org)

If one person in a family has an adverse reaction to a vaccine, will other members of the family

also have the same reaction? Is there a laboratory test that can identify whether a person

might have an adverse reaction to a vaccine before being vaccinated?

There is no single test that can determine whether a person will have an undesired reaction to a

vaccine. However, if a person has a serious allergic reaction after a vaccination, he or she may be

referred to an allergist who can attempt to determine which component of the vaccine may have

caused the reaction. If an allergy to a vaccine component is found in one person, siblings, and

children of that person can also be tested for the allergy. However, most reactions are not likely to

occur in two members of the same family.

Can vaccines cause permanent adverse events, such as a long-lasting impairment, or death?

Yes, however it is important to understand that the risk of serious adverse events is extremely small

(approximately 1 serious event occurs for each 100,000 doses of vaccine given). Most adverse

events associated with vaccines are minor and short-lived. Of those few serious adverse events

which do occur, only a small proportion result in long-lasting impairment or death. The diseases

that vaccines prevent are far more dangerous than the vaccines that effectively prevent them.

Some people believe that certain immunizations can lead to a number of chronic diseases. Many

scientific studies have been conducted to investigate these concerns. The results of this research

repeatedly point to the conclusion that vaccines do not cause chronic diseases. For example, the

Institute of Medicine, an independent research organization that is part of the National Academy of

Sciences, reviewed all existing evidence on health problems that occur after vaccination. Their

G Some scientists, and some parents, are concerned about a possible link between MMR

(measles, mumps, and rubella) vaccine and autism. It is not yet known for certain what causes

autism, but the best available evidence indicates that autism is a condition that begins before

birth (in the first trimester of pregnancy), not after a child is born. The disease is usually

diagnosed when children are 18 to 30 months old, which is the period shortly after they receive

many of the recommended vaccines. Because of this coincidence in timing, some people have

come to believe that the development of autism is somehow associated with the MMR vaccine.

With the exception of one research study, whose findings have now been widely refuted, all of

G Similarly, one investigator has suggested that the onset of diabetes might somehow be linked

to whole-cell pertussis vaccine, to

Haemophilus influenzae

type b (Hib) vaccine, the new

(also see

www.vaccines.net). Scientific research studies and research reviews, however, have all

G Other people have been concerned that vaccines may be associated with Sudden Infant Death

Syndrome (SIDS), which typically occurs in infants between 2 and 4 months of age (a period

when many immunizations are given). All scientific studies and review papers have shown that

Since 1992, the rate of SIDS in the United States has been

reduced by 40% as a result of an education campaign encouraging parents to put their babies to

Source: The National Network for Immunization Information (www.immunizationinfo.org)

G Rates of childhood asthma have increased in recent years. This increase occurred during a

period of time when the number of routine childhood immunizations also increased, so some

have speculated that these may be related. As a result, medical researchers have studied

whether vaccines might cause asthma. These studies found no increased risk of asthma after

G There has also been concern that multiple sclerosis (MS) might be associated with use of the

In 1994, the Institute of Medicine, an independent research organization

that is part of the National Academy of Sciences, reviewed all available information and

determined the evidence did not show that the vaccine causes nervous system diseases. More

recently, in 1998, the Viral Hepatitis Prevention Board of the World Health Organization asked a

panel of experts to review scientific data again. These experts also concluded that the hepatitis

B vaccine does not cause multiple sclerosis.

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Source: The National Network for Immunization Information (www.immunizationinfo.org)