Tuesday, July 05, 2011

Harvard Study Reaffirms Safety Of Flu Vaccine




Photo Credit PHIL


# 5773



Two years ago, during the run up to the fall wave of the H1N1 pandemic, the internet was filled with scare mongering over the safety of what some people deemed to be an `experimental and untested’ pandemic vaccine.


Many anti-vaccine advocates warned that we’d see thousands of cases of vaccine induced GBS (Guillain Barre Syndrome), and some insisted that the `vaccine was deadlier than the disease’.


So effective were these warnings that in August of 2009, Fox News ran a poll where just over half of its 26,000+ respondents thought taking the vaccine was riskier than catching the flu.


The reality is, the relatively mild H1N1 pandemic claimed at least 12,000 lives in the United States - mostly among those under the age of 65 - and every study over the past two years has indicated that the vaccine used in this country was extraordinarily safe.


A few past blogs on the safety of the 2009 H1N1 vaccine include:


MMRW: Surveillance For GBS Among H1N1 Vaccine Recipients
What A Difference Three Decades Makes
VAERS Vaccine Safety Report



None of which is to say that vaccines are completely benign and 100% safe. No drug or medicine can make that claim.


When millions of doses of vaccines are administered, some small number of serious adverse reactions are expected. This is true for all medications, including those you can purchase over-the-counter.


All medicines have risks.


Some are known, while others are so rare, we have trouble measuring them.  It is always a balancing act - a risk-reward calculation - when deciding to take any drug.


Today we’ve an new analysis on the safety of the 2009 pandemic and seasonal flu vaccines using data from the CDC’s VSD project, and once again the results are very reassuring.  


The report appears in the August edition of the American Journal of Preventive Medicine, and is available online now. A summary is available from the Health Behavior News Service.



Large Study Reaffirms H1N1, Seasonal Flu Vaccine Safety
Release Date: July 5, 2011


  • Both the H1N1 and seasonal influenza vaccines are safe for patients, a new Harvard study shows.
  • The CDC monitors flu vaccine safety using data from millions of U.S. children and adults.
  • Unlike the 1976 swine flu vaccine, newer flu vaccines do not put patients at risk for Guillain-Barre syndrome or Bell’s palsy.

By Emily Paulsen, Contributing Writer


At the start of the 2009-2010 flu season, the VSD Project began tracking data on a near-real time basis from eight medical organizations that together give care to 9.2 million children and adults. Each week, the organizations provided combined data for all immunizations, hospital admissions, emergency visits, outpatient encounters and diagnoses. Researchers then looked at the incidence of adverse events potentially associated with immunization, including Guillain-Barré syndrome, seizures, Bell’s palsy, other neurologic conditions and allergic reactions to detect any possible problem early enough to prevent widespread occurrence.


The analysis found no elevated risk for any adverse event, including Guillain-Barré syndrome, a condition that causes varying degrees of muscle weakness.


In the course of the study, researchers found one “safety signal,” an elevated incidence following the H1N1 vaccine of Bell’s palsy, a condition in which the muscles on one side of the face become paralyzed and which often resolves over time. When researchers dug deeper and adjusted for the fact that Bell’s palsy generally is more common during flu season  — late fall through winter — they found no association between the H1N1 vaccine and an increased incidence of Bell’s palsy.

(Continue . . . )


The entire report is available at the link below.


H1N1 and Seasonal Influenza Vaccine Safety in the Vaccine Safety Datalink Project


Grace M. Lee, MD, MPH, Sharon K. Greene, PhD, MPH, Eric S. Weintraub, MPH, James Baggs, PhD, Martin Kulldorff, PhD, Bruce H. Fireman, MA, Roger Baxter, MD, Steven J. Jacobsen, MD, PhD, Stephanie Irving, MHS, Matthew F. Daley, MD,Ruihua Yin, MS, Allison Naleway, PhD, James D. Nordin, MD, MPH, Lingling Li, PhD, Natalie McCarthy, MPH, Claudia Vellozzi, MD, Frank DeStefano, MD, MPH, Tracy A. Lieu, MD, MPH, on behalf of the Vaccine Safety Datalink Project



Not all flu vaccines are formulated the same, and there are investigations going on in Europe regarding an elevated risk of narcolepsy among adolescents who received GSK’s 2009 Pandemrix vaccine.


The total number of cases is small, and appears limited to just a few of the countries that distributed that vaccine (see EMA Recommends Interim Measures For Pandemrix Vaccine).


Regardless of how that investigation turns out, the bottom line is that we know influenza kills tens of thousands of people every year. 


Since most years the flu vaccine is 60% - 70% effective, many of those deaths could be prevented by a greater uptake of the yearly flu vaccine.

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