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MMRW: Surveillance For GBS Among H1N1 Vaccine Recipients

 

 

# 4616

 

 

The MMWR (Morbidity and Mortality Weekly Report) from the CDC has preliminary results of surveillance for GBS (Guillain Barre Syndrome) – a rare neuromuscular disease – among those who did, and did not, receive the pandemic flu shot.

 

As you may recall, for reasons that have never been adequately explained, we saw a 10-fold higher rate of GBS among recipients of the 1976 swine flu vaccine than the background rate of the disease, which caused the cessation of the vaccination program and resulted in numerous claims of damage.

 

Since that time, there has a faint link between trivalent flu vaccines and GBS, with estimates that flu vaccines might be responsible for 1 extra case of GBS out of every million shot recipients.

 

When you are dealing with side effects that are that rare, the true incidence can be very difficult to nail down.

 

The numbers are still coming in, and being analyzed, but the good news here is that the incidence of GBS among pandemic vaccine recipients appears to be in line with that which has been seen from the seasonal flu vaccine in the past.


In other words, less than 1 extra case in a million.

 

Far more people who went unvaccinated developed GBS than did those who got the vaccine.

 

Among those who were vaccinated and developed the disease, 59% reported an antecedent illness – often a trigger for GBS – and so it is by no means certain that all of those cases can be linked to the vaccine.

 

The MMWR report is lengthy, but worth reading in its entirety.  I’ve just reproduced (and reformatted) the first paragraph.

 

 

Preliminary Results: Surveillance for Guillain-Barré Syndrome After Receipt of Influenza A (H1N1) 2009 Monovalent Vaccine --- United States, 2009--2010

Early Release

June 2, 2010 / 59(Early Release);1-5

Guillain-Barré syndrome (GBS) is an uncommon peripheral neuropathy causing paralysis and in severe cases respiratory failure and death. GBS often follows an antecedent gastrointestinal or upper respiratory illness but, in rare cases, can follow vaccination.

 

In 1976, vaccination against a novel swine-origin influenza A (H1N1) virus was associated with a statistically significant increased risk for GBS in the 42 days after vaccination (approximately 10 excess cases per 1 million vaccinations), a consideration in halting the vaccination program in the context of limited influenza virus transmission (1).

 

To monitor influenza A (H1N1) 2009 monovalent vaccine safety, several federal surveillance systems, including CDC's Emerging Infections Program (EIP), are being used. In October 2009, EIP began active surveillance to assess the risk for GBS after 2009 H1N1 vaccination.

 

Preliminary results from an analysis in EIP comparing GBS patients hospitalized through March 31, 2010, who did and did not receive 2009 H1N1 vaccination showed an estimated age-adjusted rate ratio of 1.77 (GBS incidence of 1.92 per 100,000 person-years among vaccinated persons and 1.21 per 100,000 person-years among unvaccinated persons). If end-of-surveillance analysis confirms this finding, this would correspond to 0.8 excess cases of GBS per 1 million vaccinations, similar to that found in seasonal influenza vaccines (2,3).

 

No other federal system to date has detected a statistically significant association between GBS and 2009 H1N1 vaccination. Surveillance and further analyses are ongoing. The 2009 H1N1 vaccine safety profile is similar to that for seasonal influenza vaccines, which have an excellent safety record.

Vaccination remains the most effective method to prevent serious illness and death from 2009 H1N1 influenza infection; illness from the 2009 H1N1 influenza virus has been associated with a hospitalization rate of 222 per 1 million and a death rate of 9.7 per 1 million population.

 

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