Archived: Vaccine Safety

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The National Network for Immunization Information (NNii) provides up-to-date, science-based information to healthcare professionals, the media, and the public: everyone who needs to know the facts about vaccines and immunization.

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As with all medications, there are risks and side effects with vaccines, although serious side effects are mostly rare. There are various tools and programs to monitor and study vaccine safety, either before or after vaccine licensure.

This section explains how vaccine safety research and monitoring is done.

Asthma and Vaccines

The prevalence of childhood asthma has been increasing in the past two decades in the United States.  Some have suggested that this increase may be due to vaccinations, although recent studies do not support that hypothesis.

Updated: July 19, 2004 | Read full article...

BSE Transmission and Vaccines

The Food and Drug Administration Center for Biologics Evaluation and Research (CBER) conducted a careful review of the science relating to risk of bovine spongiform encephalopathy (BSE) transmission through use of vaccines.

Updated: June 10, 2004 | Read full article...

Causa o Coincidencia

Cuando un efecto adverso ocurre después de la vacunación, es necesario determinar si fue causado por la vacuna o fue coincidencia en el momento de la administración de la vacuna-esto quiere decir que de todos modos iba a suceder. ¿Cómo determinan los investigadores si la vacuna causa una enfermedad particular o no?

Updated: August 26, 2011 | Read full article...

Cause or Coincidence

When an adverse event occurs after vaccination, it needs to be determined whether the adverse event was caused by the vaccine or whether it was just coincidental in time with the administration of the vaccine—that is, it was going to happen anyway. How can researchers determine if a vaccine causes a particular disease or not?

Updated: August 28, 2006 | Read full article...

Concerns About Vaccine Safety

Because of the success of vaccines, vaccine-preventable diseases aren’t feared anymore and concerns about vaccine safety are common. But these diseases are not gone.

Updated: February 12, 2009 | Read full article...

El asma y las vacunas

La prevalencia de asma en la niñez ha incrementado en las últimas dos décadas en los Estados Unidos. Algunos han sugerido que este incremento puede ser debido a las vacunas, sin embargo, estudios recientes no apoyan esta hipótesis.

Updated: September 27, 2011 | Read full article...

Hepatitis B Vaccine and Multiple Sclerosis

Although scientific data show that HBV vaccine is very safe, anecdotes have caused some to hypothesize that HBV vaccine might be associated with an increased risk of demyelinating neurological disorders, such as multiple sclerosis.

Updated: September 29, 2004 | Read full article...

Vaccine Adverse Event Reporting System

The Vaccine Adverse Event Reporting System (VAERS) is a national system for reporting possible adverse reactions or side effects after any US-licensed vaccine. This article explains how VAERS works and describes its strenghts and limitations.

Updated: February 12, 2009 | Read full article...

Vaccine Safety Datalink

The VSD project was created in 1990 by the Centers for Disease Control and Prevention (CDC) and currently involves partnerships with 8 large health maintenance organizations (HMOs) to continually monitor vaccine safety.

Updated: February 12, 2009 | Read full article...