H1NI Vaccine Safety Surveillance Would Likely Involve Neurologists
If the federal government decides to offer a vaccine for the new H1N1 influenza virus — the so-called swine flu — neurologists could play an important role in monitoring its safety, according to a government epidemiologist involved in the discussions.
James Sejvar, MD, a neuroepidemiologist at the Centers for Disease Control and Prevention (CDC), told Neurology Today said that while health officials have not made a decision on whether to proceed with an H1N1 vaccine, it has discussed the need for increased vigilance for the type of neurologic complications that surfaced during the 1976 immunization drive against swine flu.
That effort, which resulted in the immunization of more than 40 million Americans, was halted less than three months after it began because of numerous reports of people developing Guillain-Barré syndrome (GBS) within weeks of getting vaccinated. Moreover, the feared pandemic of swine flu that prompted the immunization push never materialized — a fact surely in health officials' minds this time around as they weigh the pros and cons of a vaccination campaign.
“There are discussions about formulating a specific vaccine for the H1N1 virus and if such as vaccine was formulated, it would be given in addition to the routine seasonal influenza vaccine,” said Dr. Sejvar, of the CDC National Center for Zoonotic, Vector-Borne, and Enteric Diseases. “While discussions are ongoing about whether the H1N1 vaccine will be used, we're also discussing the most optimal ways of conducting surveillance for possible adverse events associated with the vaccine. It's likely that neurologists would play a critical role in assisting with surveillance for Guillain-Barré and other possible neurologic events.”
Health officials are considering sending alerts out through the AAN Web site, www.AAN.com, as well as e-mail blasts, and postal mailings to neurologists around the country to quickly flag potential problems, Dr. Sejvar said.
Health officials learned many lessons from the 1976 swine flu immunization campaign, including the importance of conveying information to the public clearly and without hype. The years since have also led to stepped-up efforts to detect possible complications of the vaccine.
“In 1976, that particular vaccine formulation did seem to be associated with a small but increased risk for the Guillain-Barré syndrome in the weeks following immunization,” Dr. Sejvar said. If vaccination proceeds this time, “I think there are people who are going to recall the problems experienced with that particular (1976) vaccine.”
A NOVEL VIRUS
Dr Sejvar said that so far there has been no evidence that the new influenza A (H1N1) strain has caused neurological complications in infected people. The novel virus was first detected in April in Mexico after people began to get sick, and in some cases die, from flu-like symptoms. Since then, there have been 5,728 confirmed cases in 33 countries, according to a May 13 report by the World Health Organization. In this country, there were 3,352 confirmed cases in 43 states and three deaths are documented, the CDC said.
Cases in the US have tended, for reasons that aren't clear, to be milder than those in Mexico. Officials have said that the H1N1 strain doesn't have the genetic traits that tend to make viruses particularly virulent, but that doesn't mean there isn't reason for concern. Because of the novel nature of the virus, most people do not have immunity, and it's possible the virus could evolve into an even more troublesome strain.
HISTORY PROVIDES A GOOD LESSON
The 1976 immunization drive was prompted by an outbreak of swine flu among soldiers at Fort Dix in New Jersey. Federal officials feared a replay of the deadly 1918 flu pandemic and moved quickly to implement a mass immunization drive. Tens of millions of Americans rolled up their sleeves, but the campaign quickly became problematic when reports surfaced that people were developing the Guillain-Barré syndrome.
Just how many people developed neurological complications from the shot has never been precisely agreed upon, and why the shot caused problems is still decades later the subject of scientific discussion.
An August 1979 article in the American Journal of Epidemiology reported that “surveillance uncovered a total of 1098 patients with onset of GBS from October 1, 1976, to January 31, 1977.” Of those, 532 patients had recently received the swine flu shot and another 15 were vaccinated after they developed GBS symptoms. The article concluded: “When compared to the unvaccinated population, the vaccinated population had a significantly elevated attack rate in every adult age group,” with most of the affected people sickened within five weeks of immunization. The vaccine has been blamed for upwards of 25 deaths.
Steven P. Ringel, MD, associate editor-in-chief of Neurology Today and a professor of neurology at the University of Colorado-Denver, was an expert witness on GBS for the federal government in the 10th Circuit in Denver for lawsuits stemming from the 1976 immunization drive.
“We didn't have good reporting of GBS at the time,” Dr. Ringel told Neurology Today, so it was difficult to say how many cases were due to the vaccine, as opposed to cases that resulted, for instance, as a result of infection with regular seasonal flu.
“There were a lot of people coming out of the woodwork saying they had Guillain-Barré and it was caused by the shot,” he said.
Dr. Ringel said he doubted that the federal government will move to offer immunization against this latest H1N1 virus; but no matter what happens, he said 1976 should serve as a reminder of the importance of having good surveillance systems in place to look for complications.
“Like all immunizations, you have to weigh the costs, risks, and benefits and any decision should not be made precipitously,” he said.
Raymond Roos, MD, the Marjorie and Robert E. Straus Professor in Neurological Science at the University of Chicago, said it's not necessarily easy to get a firm measure of vaccine-related Guillain-Barré syndrome because “there is always a background of Guillain-Barré” in the population. Typically there are about 1.5 cases per 100,000 people, he said. Most of the serious cases come to the attention of a neurologist, and fewer major cases might be handled by a primary care physician. Also, milder symptoms from other causes may inaccurately be blamed on GBS.
Dr. Roos, who served as chairman of the FDA Vaccines and Related Biological Products Advisory Committee in 1995 and 1996, said he was confident federal health officials will take great care in deciding if and how to implement a vaccine program against the current H1N1 virus.
“The world is much better prepared now than it was in the 1970s in terms of assessing the risk, in guiding the decision-making, and also more knowledgeable about how to communicate information to the public,” he said. “If there is a H1N1 vaccine program, I think it would be valuable to accurately assess the incidence of Guillain-Barré by setting up an active and thorough surveillance system and zeroing in on a particular community or several communities or states.”
The federal government conducts surveillance for vaccine complications through its Vaccine Adverse Event Reporting System and the Vaccine Safety Datalink Project, which involves the review of immunization records of patients from eight geographically diverse sites.