Reported cases of Guillain-Barré syndrome do not appear higher than for seasonal flu shots. (Ryan Remiorz/Canadian Press)

The H1N1 vaccine was not linked to a spike in cases of a rare paralyzing condition as some had feared, a U.S. study suggests.

Researchers in the U.S. checked for reports of a neurologic disease called Guillain-Barré syndrome and reported their results Tuesday at the American Academy of Neurology's annual conference in Toronto.

In the rare disorder, the body's immune system attacks part of the peripheral nervous system, causing tingling and weakness in the arms of legs.

There were 35 reported cases of GBS following H1N1 vaccination in the U.S. by the end of 2009, which amounts to 3.5 reports of GBS per 10 million people vaccinated — reporting rates that don't appear to be higher than for seasonal flu shots.

All cases of GBS except one were reported within six weeks of vaccination, said study author Dr. Nizar Souayah of the New Jersey Medical School in Newark.

"Although preliminary, these reported cases of GBS do not appear to show an increased risk of GBS following vaccination with either the 2009 H1N1 or the seasonal flu strain and the safety record for these vaccines is excellent," Souayah said.

Souayah analyzed data from the U.S. Centers for Disease Control and Prevention and the U.S. Food and Drug Administration's Vaccine Adverse Event Reporting System or VAERS.

Of the 33 patients hospitalized with GBS, there was one report of death and one of permanent disability.

VAERS cannot be used to determine cause and effect, and adverse event reports only indicate that an event occurred after vaccination. The GBS reports need to be validated, Souayah said.

Patient reports GBS case

Donna Hartlen, 39, of Whitby, Ont., says there is no question there is a link between H1N1 vaccination and GBS in her case.

Hartlen had an H1N1 shot and 13 days later she said she was on her way "to being paralyzed." The mother of two toddlers has been told it will take a year to regain complete movement and sensation on one side of her face, and in her hands and feet.

Hartlen questions the reliability of the data used in the study. In the U.S., as in Canada, doctors don't have to report vaccine side-effects.

"At no time did I hear from a physician that it would be reported, so I called public health myself and I reported the GBS," Hartlen said.

Coincidentally, a man who was vaccinated the same day in the same clinic as Hartlen ended up in a hospital bed next to her, also diagnosed with GBS.

CDC epidemiologist Dr. James Sejvar said the potential risks associated with the H1N1 vaccine are far outweighed by the benefits.

"Rest assured we are doing additional active population-based studies to more proactively assess its risks," said Sejvar. CDC is checking real time data to monitor the safety of the H1N1 and other vaccines, he added.

As of February 11, the Public Health Agency of Canada's website shows 26 reported cases of GBS in Canadians who received the H1N1 vaccine or one case per million doses distributed. The cases reported following H1N1 vaccinations are under investigation, the agency said.