Neurological and autoimmune disorders after influenza vaccination: no change in risk for Guillain-Barré syndrome, MS, type 1 diabetes, or RA

This Swedish retrospective cohort study, published in BMJ, examined the risk of neurological and autoimmune disorders in people vaccinated against pandemic influenza A (H1N1) with Pandemrix (GlaxoSmithKline) compared with unvaccinated people over 8-10 months.


Image of the H1N1 Influenza Virus, CDC.

One million people were vaccinated against H1N1 and 900,000 remained unvaccinated.

Excess risks among vaccinated people were of low magnitude, but present, for:

- Bell’s palsy (hazard ratio 1.25)
- paresthesia (1.11)
- inflammatory bowel disease (IBD)

Risks for Guillain-Barré syndrome, multiple sclerosis, type 1 diabetes, and rheumatoid arthritis remained unchanged.

The risks of paresthesia and inflammatory bowel disease (IBD) among those vaccinated in the early phase (within 45 days) of the vaccination campaign were significantly increased; the risk being increased within the first 6 weeks after vaccination.

The risks were small but significant among more than one million vaccinated, but only in high risk groups targeted for early vaccination and who were likely to have earlier comorbidity.

The absolute risk of Bell’s palsy was low, 6.4 cases per 100 000 vaccinated population.

References:

Neurological and autoimmune disorders after vaccination against pandemic influenza A (H1N1) with a monovalent adjuvanted vaccine: population based cohort study in Stockholm, Sweden. BMJ 2011; 343:d5956 doi: 10.1136/bmj.d5956 (Published 12 October 2011).

Low risk of transmission of influenza on the plane: 3.5% if sitting within 2 rows of infected passengers

This BMJ study assessed the risk of transmission of pandemic A/H1N1 2009 influenza (pandemic A/H1N1) from an infected high school group to other passengers on an airline flight and the effectiveness of screening and follow-up of exposed passengers.

The design was a retrospective cohort investigation using a questionnaire administered to passengers and laboratory investigation of those with symptoms.

The setting was in Auckland, New Zealand, with national and international follow-up of passengers. The participants were passengers seated in the rear section of a Boeing 747-400 long haul flight that arrived on 25 April 2009, including a group of 24 students and teachers and 97 (out of 102) other passengers in the same section of the plane who agreed to be interviewed.

9 members of the school group were laboratory confirmed cases of pandemic A/H1N1 infection and had symptoms during the flight. Two other passengers developed confirmed pandemic A/H1N1 infection. Their seating was within two rows of infected passengers, implying a risk of infection of about 3.5% for the 57 passengers in those rows.

A low but measurable risk of transmission of pandemic A/H1N1 exists during modern commercial air travel. This risk is concentrated close to infected passengers with symptoms.

Video: "How to Sneeze" Demonstrated by the U.S. Health and Human Services Secretary Kathleen Sebelius. She shows NBC’s Chuck Todd the “Elmo way” to sneeze.

Don't forget to get your influenza immunization (flu shot or spray) this season. The CDC video embedded below clearly explains why this is extremely important.


CDC video: Why Flu Vaccination Matters: Personal Stories from Families Affected by Flu.

References:

Transmission of pandemic A/H1N1 2009 influenza on passenger aircraft: retrospective cohort study. BMJ 2010; 340:c2424 doi: 10.1136/bmj.c2424 (Published 21 May 2010).

Diagram of influenza virus nomenclature. Image source: Wikipedia, GNU Free Documentation License.